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DEPARTMENTAL COMMITTEE ON LIGHTING IN
G-1 FACTORIES AND WORKSHOPS.
C 3 9015 00353'25"; FIRST REPORT
University of Michigan - BUHR -
OF THE
DEPARTMENTAL COMMITTEE
ON
LIGHTING
IN
FACTORIES AND WORKSHOPS.
VOL. I. REPORT AND APPENDICES.
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The following is a list of some recent Parliamentary and Official Publications —-
FACTORIES AND WORKSHOPS.
ANNUAL REPORT OF THE CHIEF INSPECTOR FOR 1913.
The General Report is followed by a Divisional Report dealing with Industrial Develop-
ments and State of Trade ; Sanitation, including Ventilation, the Effect of Steam in Dye-houses,
and of Dust in Cotton Waste Willowing, and in Flax Scutch Mills; Safety ; Dangerous Trades,
with a section on Flax, Hemp and Jute ; Employment ; Particulars of Textile and Non-Textile
* 4. r- rarx: - - r < ºrºrº s 'i , - 'º-N > * , s: - - . . . . . . . . . . . * *.' T : º * . *
Factories, and of Truck. The Report of the Principal Lady. Inspector of Factories, and of the
Electrical Inspectoi, and of the Medical Inspectors are appended. With Tables and Index.
{
(d. 7491] of Session 1914. Price is. 7d., post free ls. I id.
INDUSTRIAL POISONING, ACCIDENTS, AND DANGEROUS OCCURRENCES.
PRELIMINARY TABLEs (subject to correction) of Cases of Industrial Poisoning, Fatal and
Non-Fatal Accidents, and Dangerous Occurrences in Factories, Workshops, &c., during the
Year 1913. - - 2. - - - - - - - -
[Cd. 7309) of Session 1914. Price Id., post free lºd.
ELECTRICITY REGULATIONS. -
MEMORANDUM by the Electrical Inspector of Factories. Form 928. Feb. 1910. (1910.)
Price 3d., post free 4d.
HYGROMETERS ORDER, MARCH 18, 1912,
In pursuance of the Regulations for Cotton Cloth Factories. (1912.) Price Id., post free lºd.
WENTILATION OF FACTORIES AND WORKSHOPS.
FIRST REPORT of THE DEPARTMENTAL COMMITTEE.
Deals with general ventilation for getting rid of impurities due to presence of employees,
and of lights burning. The results of the examination of the ventilation of Factories and
Workshops visited by the Committee. Conditions on which efficient ventilation depends.
Method for determining amount of Carbonic Acid in the Air, with diagrams of portable apparatus
for estimating the amount. -
[Cd. 1302} of Session 1902. Price 1s. 8d., post free 1s. 11d.
SECOND REPORT OF THE DEPARTMENTAL COMMITTEE.
Deals with the application of fans to factory ventilation, in connection with the removal
of dust, fumes, steam and other impurities associated with special manufacturing processes ;
also with the question of respirators. With illustrations. . . . . .
[Cd. 3552] of Session 1907. Price 3d., post free 4d.
APPENDIX TO SECOND REPORT.
Contains plates and diagrams explaining the results of experiments carried out by the
Committee and illustrating their recommendations. Experiments on the construction of main
ducts and the arrangement of throats or branches. Illustrations of local ventilation and
removal of dust by propeller and centrifugal fans, and notes on practical construction and use
of ducts, hoods and gratings. - - . . . . . ... •
[Cd. 3553 of Session 1907. Price 4s. 5d., post free 4s. 8d.
DLAGRAMS showing methods of extracting dust rh different processes in flax, hemp, jute,
and tow manufactures, wool-sorting and wool-combing works, metal grinding and polishing, &c.;
also various systems for humidifying workrooms, compiled by Commander Sir Hamilton
P. Freer-Smith, R.N., including for the information of manufacturers a number of examples of
well-planned installations which in practice have secured the desired results.
[Cd. 3223 of Session 1906. Price 4s. 10d., post free 5s. 1d.
x (6)30030
HOME OFFICE.
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES
AND WORKSHOPS. -
FIRST REPORT
OF THE
DEPARTMENTAL COMMITTEE
ON
LIGHTING
IN
FACTORIES AND WORKSHOPS.
WOL. I.-REPORT AND APPENDICES.
iſresented to both gouges of parliament by command of his guajesty.
- LoND ON : .
PRINTED UNDER THE AUTHORITY OF HIS MAJESTY'S STATIONERY OFFICE
By EYRE AND SPOTTISWOODE, LIMITED, EAST HARDING STREET, E.C.,
PRINTERs To THE KING's Most ExCELLENT MAJESTY.
To be purchased, either directly or through any Bookseller, from
WYMAN AND SONS, LIMITED, 29, BREAMs BUILDINGS, FETTER LANE, E.C., and
28, ABINGDON STREET, S.W., and 54, ST. MARY STREET, CARDIFF ; or
H.M. STATIONERY OFFICE (Scottish BRANCH), 23, FoRTH STREET, EDINBURGH : or
E. PONSONBY, LIMITED, 116, GRAFTON STREET, DUBLIN :
or from the Agencies in the British Colonies and Dependencies,
the United States of America and other Foreign Countries of
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** - 1915.
[Cd. 8000.] Price 11d.

co NT EN
TS.
REPORT.
Warrant of Appointment - - -
Introduction - -> - - - - -
Methods of Investigation º - - º
Witnesses - tº- - - " * -
Assistance from Trade Associations - º
H.M. Inspectors of Factories
35 35 33
Visits of Inspection - * - *
Experimental Work - wº- - -
Explanation of Technical Terms - * gº
Illumination - - - - -
Surface Brightness t- - * º
Glare º - - - - º
“Frequency of Occurrence " Curves º -
Daylight Factor - º - * -
Tactors in Good Lighting - - - es
Existing Requirements as to Lighting - tºs
Statutory - -- - º - -
Official ºs - º tº- -. , -
Present Lighting of Factories and Workshops •.
Natural Lighting - - º - tº-
Artificial Lighting -
Causes of Unsatisfactory Illumination w *
Natural Lighting - º
Artificial Lighting - * - º tº-
Effects of Unsatisfactory Illumination - -
Accidents - - - - º tº-
Damage to Eyesight and Health - tº -
Insanitary Conditions º tº- - tº-
Diminished Output of Work - tº- -
Lack of Discipline e- tº- - -
Recommendations - º - - -
General - - * 1- - º-
Standards of Adequacy - - * t-
Workrooms - * tº- * -
Passages, &c. - º - wº- t-
Open Yards and Approaches - -
Exemptions - -- º º -
Cleanliness of Windows - - * wº-
Conclusion º - º - *g tº-
Professional and Scientific Societies
APPENDICES.
APPENDIx I–List of Witnesses examined -
APPENDIX II.-List of Factories visited - -
APPENDIX III—Circular Letter to Trade Associations
APPENDIX IV.-Approximate Number of Persons employed in the Principal Industries (1907)
APPENDIX W.—Summary of Reports received from H.M. Inspectors of Factories
APPENDIX VI.-Memorandum on Investigations carried out by the Factory Department, &c.
APPENDIX VII.-Requirements as to Lighting of Factories, Schools, &c., in the United Kingdom
APPENDIX VIII-Requirements as to Lighting of Factories, Schools, &c., in Foreign Countries
APPENDIX IX—Memorandum on Accidents in Factories -
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E’AGE
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APPENDIX X.—Note on Influence of Lateral Illumination on visual Acuity
APPENDIX XI.-Extract from Professor Snellen's Bowman Lecture (1896)
APPENDIx |XII.--Summary of Replies to Questions by F. Richardson Cross, F.R.C.S.
APPENDIX XIII–Replies to Circular Letter as to Evidence of Injury to Eyesight in certain
Trades - • *
APPENDIX XIV.-Experimental Room at the National Physical Laboratory and some Investiga-
tions carried out in it - - *
APPENDIX XV.--Summaries of Illumination Measurements in Factories and Workshops -
Introduction - - - ſº
Factory Floors - - * tº .
Textile Industry - - º
Weaving º - e- º
Spinning, &c., and Incidental Processes
Lace and Hosiery Making - tº-
Engineering Industry - * sº -
General Engineering (excluding Foundries)
Foundries - - - º
Making up of clothing and similar work
Miscellaneous industries - -
APPENDIX XVI—Memorandum on Daylight Illumination -
APPENDIx -- XVII.-The Measurement of Illumination gº
a (6)30030 Wt 1650 2500 9/15
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Warrant of Appointment.
I hereby appoint—
Dr. R. T. GLAZEBROOK, C.B., D.Sc., F.R.S., Director of the National
Physical Laboratory,
Mr. LEON GASTER, .
Professor FRANCIS GOTCH, D.Sc., F.R.S.,
Mr. J. HERBERT PARSONS, M.B., D.Sc., F.R.C.S.,
Mr. W. C. D. WHETHAM, F.R.S.,
Sir ARTHUR WHITELEGGE, K.C.B., Chief Inspector of Factories,
to be a Committee to inquire and report as to the conditions necessary for the
adequate and suitable lighting (natural and artificial) of factories and workshops,
having regard to the nature of the work carried on, the protection of the eyesight
of the persons employed, and the various forms of illumination; *
And I further appoint Dr. Glazebrook to be Chairman of the Committee, and
Mr. D. R. Wilson, one of H.M. Inspectors of Factories, and Mr. C. C. Paterson,
M.I.E.E., A.M.I.C.E., of the National Physical Laboratory, to be Secretaries to the
Committee. -
- R. McKENNA.
Home Office, • -
17th January 1913.
I hereby appoint Professor C. S. Sherrington, M.A., M.D., D.Sc., F.R.S., to be
an additional Member of the Departmental Committee on the Lighting in Factories
and Workshops. -
- R. McKENNA.
Home Office,
29th May 1913.
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND.
WORKSHOPS.
R. E. P. O. R. T.
To THE RIGHT HONOURABLE REGINALD McKENNA, M.P., SECRETARY OF STATE FOR
THE HOME DEPARTMENT.
SIR, London, May, 1915.
WE have the honour to present the following First Report on the Lighting
of Factories and Workshops. - - w
The Committee met for the first time in London on the 11th February 1913.
Since then 38 meetings have been held.
In view of the wide ground covered by the terms of reference, it was thought
desirable to limit the inquiry in the first instance as far as possible to the textile,
engineering, and clothing trades, certain general principles, common to all trades,
however, being also taken into consideration. These industries were chosen as being
the largest from the point of view of the number of persons employed" and also as
affording great diversity in character and requirements.
With deep regret we have to record the death at an early stage of our pro-
ceedings of our colleague, Professor Francis Gotch, D.Sc., F.R.S. His intimate
special knowledge of the physiological aspect of the questions referred to us would
have been of the greatest value to us, and we would take this opportunity of
acknowledging the very serious loss to the Committee entailed by his death.
Professor C. S. Sherrington, D.Sc., F.R.S., was subsequently appointed by you to fill
the vacancy.
METHODS OF INVESTIGATION.
1. WITNESSES.—The witnesses called and examined by us numbered 50 in all,
and included the following:—
(a) Official:—
5 of H.M. Inspectors of Factories.
1 Medical Officer of Health.
1 Factory Certifying Surgeon.
(b) Professional, technical and scientific :—
6 Illuminating Engineering Experts.
5 representatives of Professional and Scientific Societies.
6 Architects and Surveyors. N
3 Medical Experts.
(c) Representatives of trade associations —
11 witnesses representing Employers.
9 witnesses representing Operatives.
A full list of the witnesses appears in Appendix I.
2. AssISTANCE FROM TRADE ASSOCIATIONS.—A circular letter (Appendix III.)
was sent out to 79 associations (33 representing the employers and 46 the
operatives), explaining the objects of our Inquiry and asking for evidence
and other assistance. To this invitation 31 replies were received (10 from
employers' and 13 from operatives' associations), in most of which information was
given, and the evidence, to which reference has already been made, was tendered.
An attempt has been made to summarise and classify the evidence received from
witnesses, and the summary will be found, together with the usual verbatim record,
in the Minutes of Evidence. º
We desire to acknowledge the great assistance thus afforded, without which inquiry
into the matters referred to us would not have been possible. º,
3. AssistANCE FROM H.M. INSPECTORS OF FACTORIES.–In addition to the evidence
received from H.M. Inspectors of Factories who appeared as witnesses, specific
questions were addressed in writing to the whole staff, and much valuable information
was derived from their replies, which will be found summarised in Appendix V.
* See Appendix IV.
a 30030 A 3
iii DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND workSHOPS:
4. AssistANCE FROM PROFESSIONAL AND SCIENTIFIC SOCIETIES.--We are indebted
to the following societies for their assistance in nominating witnesses at Our
request:— -
The Illuminating Engineering Society.
The Institution of Electrical Engineers. –
The Institution of Gas Engineers.
The Ophthalmological Society of the United Kingdom.
The Royal Society of Medicine.
The Royal College of Surgeons.
The Royal Institute of British Architects.
The Surveyors' Institution.
5. VISITs of INSPECTION.—With the object of seeing both natural and artificial
lighting conditions, several tours through industrial parts of the country were
undertaken during the winter. The chief centres visited were London, Glasgow,
Newcastle-on-Tyne, Leeds, Sheffield, Manchester, Liverpool, Bristol, and Belfast.
It had been our intention to include in these tours visits to Birmingham and Cardiff,
but the time available proved to be inadequate, and we were compelled to postpone
them. The works inspected were confined in the main to the three industries
already mentioned, and numbered 86 in all. We would take this opportunity of
acknowledging the assistance and courtesy universally accorded us. A full list
appears in Appendix II.
6. ExPERIMENTAL WORK.—(a) Measurements in Factories.—At the outset of the
investigation it was thought desirable to obtain data of the lighting conditions
(both natural and artificial) existing in factories at the present time. Arrangements
were made accordingly for taking a large number of measurements in representative
factories and workshops, chiefly in the three industries already mentioned. As a rule,
these measurements were made previously to the tours of inspection referred to
under (5), so that on the occasions of many of the visits, definite facts were available
as to the illumination of the factories inspected. .
In the course of the investigation about 4,000 measurements were made in
163 rooms of 57 factories by Mr. J. W. T. Walsh, B.Sc., of the National Physical
Laboratory, and Mr. G. F. Sedgwick, H.M. Inspectors' Assistant. The full data
collected are published separately", together with particulars as to the dimensions of
the various rooms, the size of windows, and the number and nature of the light sources
installed. The rooms are grouped according to the nature of the work carried
on in them, and each such group is preceded by a short memorandum summarising
the results and emphasising any features of special moment. The notes made by
the Committee when visiting each room on the tour of inspection are given with
the records for that room. A complete summary of the results of observations, together
with a general discussion of the principles which have been followed in making and
recording the measurements, is appended to this Report.”
(b) Measurements at the National Physical Laboratory.—In order to carry out
observations under conditions which could be controlled with ease and precision,
arrangements were made for a room to be prepared for the use of the Committee
at the National Physical laboratory. In this the nature of the lighting could be
changed and the degree of illumination varied at will. Besides experiments in which
the members of the Committee themselves took part, tests were made in this room
with workpeople, in Order to ascertain what illumination is required for various
processes in the clothing industry. Details of this room and an account of experiments
made in it are given in Appendix XIV.
EXPLANATION OF TECHNICAL TERMS.
A surface appears to the eye to be illuminated because of its capacity for reflecting
and diffusing light which reaches it by radiation from the various sources in its
neighbourhood. Such sources may be artificial (e.g., gas lamps) or natural (e.g., white
clouds or the sun). -
A clear distinction must be drawn between illumination and surface brightness.
Briefly expressed, illumination is measured by the amount of light received on the
surface of an object from surrounding sources, while surface brightness is measured
by the amount of light returned from the surface. In the case of non-luminous bodies
| Results of Observations of Illumination in Factories (Stationery Office Publication). * Appendix XV.
REPORT. - iv.
the surface brightness is always less than the illumination, for no surface returns
again all the light which falls on it. If we have three different surfaces, each exposed
to its own light source, we can adjust the sources to give equal illumination at each
surface. The surfaces will not generally look equally bright, for the amount of light
each returns to the eye of the observer will differ; in other words, each has a different
surface brightness. On the other hand, we can adjust the sources so that all three
surfaces look equally bright, and each will then have the same surface brightness;
in this case the illumination at each surface will be different. White cardboard .
returns nearly all the light falling on it, so that under a high illumination it will have
a high surface brightness; a black floor or foundry sand returns only a small
percentage of the incident light, and under similar conditions its surface brightness
will be low.
. ... 1. ILLUMINATION.—The illumination at any surface is proportional to the amount
of light incident on it, and when we speak of the “Illumination ” at a point of
a surface we mean the amount of light which falls on a unit of area of the surface
adjacent to the point. This can readily be measured by means of illumination
photometers, of which there are several portable types at the present time."
The illumination at a surface depends not merely on the strength or candle-
power of the source of light to which the illumination is due, but also on the distance
Of the source from the surface. Thus, apart from reflection from surrounding bodies,
a light-source of one candle placed at a distance of two feet from a surface produces
at that surface only one-fourth of the illumination it would give if the distance
Were reduced to One foot. Again, the amount of light from a given source which
falls on any portion of a surface depends both on the distance of the surface from
the source and on the angle at, which the light rays strike the surface. If the
part of the surface considered is placed at right angles to the direction of the
light, a maximum number of rays will meet it, and its illumination, therefore,
will be greater than if placed in any other position so that the light rays strike
it obliquely. Hence in the consideration of the illumination in any room it is
not correct, as has sometimes been the practice, to take as a criterion the total
candle-power of the sources of light, or the candle-power per square foot of floor
area or per cubic foot of total volume, for all such methods leave out of account the
effect of the distance of the light sources from the benches or floors which require to
be illuminated. We consider, therefore, that the only rational criterion of the adequacy
of the lighting is the actual illumination at the place, for instance, where work is
being carried out, or in the case of gangways and passages, at the floors over which
people are liable to pass. -
The now accepted unit of illumination in this country is the “foot-candle.”
One foot-candle may be defined as the illumination produced by a light source of
One standard candle at a point of a surface one foot from the source and so placed
that the light rays from the source strike the surface at right angles.
Thus if a source of One candle be placed at a height of one foot above a
horizontal table, the illumination at the point on the table vertically below the source
is one foot-candle. Similarly, with a source of 50 candles at a distance of one foot,
the illumination is 50 foot-candles, while if the distance is increased to 10 feet, since the
illumination is inversely proportional to the square of the distance from the source, the
illumination at the point on the table vertically below the lamp will be 50/100, or
0. 5 foot-candle. If the point on the table is not vertically below the source, the
obliquity at which the light is incident must be taken into account, and the calculation
is less simple, but the illumination can still be expressed in foot-candles. As already
mentioned, however, illumination can always be measured directly by means of
suitable instruments without recourse to calculation.
2. SURFACE BRIGHTNESS.—We see a body by means of the light which reaches
the eye from its surface. If the surface is self-luminous, the light is due to the body
itself, and the apparent brightness of the body depends on the intensity of the actions
to which the luminosity is due. This is the case in a gas flame or in the filament of
* Appendix XVII. The accuracy with which illumination measurements can be made with properly
constructed and calibrated portable photometers is of the order of plus or minus 5 per cent. An allowance
of plus or minus 10 per cent. should afford a sufficient margin to cover the instrumental errors of such
apparatus. -.
* The “foot-candle” is the unit generally employed in this country. On the continent of Europe
the “meter-candle,” with a value roughly of one-tenth of a foot-candle, is used almost exclusively.
A 4
‘V DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND worksHoPs :
an electric lamp. If the body is not self-luminous, its brightness depends on the nature
and colour of its surface and on the amount of light falling on it. The light by which
an observer sees the body comes from the source which is illuminating the body and is
reflected by the body to the observer. Some portion of the light is reflected regularly
according to the laws of reflection, and its amount depends on the angle at which the
incident light falls on the body, but unless the surface of the body is polished, the larger
portion of the light is diffused by the surface, being reflected in all directions, and it is
with this diffused light that we are mainly concerned in the case of vision. The amount
of light reaching the eye from a given area of an illuminated surface depends upon
the nature of the surface, the angle at which it is viewed, and the amount and direction
of incidence of the light by which it is illuminated. We may imagine the luminosity
of the surface to be due to a number of sources of light, each of definite candle
power, so distributed Over the surface as to secure that the proper amount of light
travels in the direction in question from each unit of area. We may thus measure
surface brightness in candles per unit area. Again, the apparent size of any portion
of a surface depends on the angle at which it is viewed. In estimating the
relative brightness of different parts of the surface, the eye does not compare the
amounts of light coming from equal areas, but the amounts which come from areas
which appear equal—from areas, that is to say, whose projections at right angles to the
line of vision are equal. It is convenient, therefore, to define brightness with reference
to these projected areas, and to say that the amount of light travelling in a given
direction from an area of the surface whose projection at right angles to the line of
vision is unity, measures the surface brightness estimated in that direction.
The quantity of light returned from any surface depends, as already stated, on
various conditions. An ideally white surface is one that returns all the light falling
On it. The brightness of such a surface would be numerically equal to its illumination,
which is measured in foot-candles. Thus surface brightness, like illumination, may be
expressed in foot-candles, and is then measured by the illumination at an ideally
white surface just matching in brightness the surface under consideration. In the
estimation of the illumination requisite for any given work, the nature of the surface
on which the work is being done is, therefore, an important factor.
A surface appears coloured when it returns some rays of the spectrum more
copiously than others. Thus a red surface is one which absorbs most of the rays
except the red, and allows a preponderance of the latter to reach the eye. Such a
surface behaves very differently to red and to blue light, but the distinction between
illumination and surface brightness still remains. -
3. GLARE.--The term “glare’ is often used to indicate the serious effects on the eye
of an intensely incandescent body, such as the sun or molten metal, but is now very
generally applied to a class of phenomena in which light from bright sources or
objects enters the eye in such a manner as to cause annoyance, headache, and
other trouble, and often, eventually, diminished ability to see. The word “glare’’ is
used to cover any of the following phenomena:-
(1) The effect of looking directly at a bright source of light, such as an arc lamp,
so that the observer is for the time being prevented from seeing other
objects properly. He is temporarily dazzled and his vision is impaired for
a short period after the light has ceased to enter his eyes.
(2) The effect which is produced by the presence of one or more bright sources
of light towards the edge of the field of vision so that the rays enter the
eye obliquely from them. An observer may never look directly at such
sources of light, but he is nevertheless troubled by their presence near to
the object at which he is looking. This is the commonest form of glare.
Both the above forms of glare (1) and (2) are directly attributable to the
presence of unshaded sources of light.
(3) The effect which is produced when the surface of cloth, metal, paper, or other
material being worked upon is shiny or polished, and reflects light
directly from some source into the eyes of the worker. Many satin
cloths, for instance, have a “sheen. ” or a power of regular reflection
of light which causes work with such materials to be very trying unless
the worker is so placed with reference to the source of light that none
of the rays can be directly reflected from the material into his eyes.
4., “FREQUENCY OF OCCURRENCE" CURVES.–It is convenient to employ a graphic
method of setting forth the results of observations of illumination in factories to
show what are the most general illuminations at present prevailing in any class of
factories or processes. Curves may be drawn to represent the frequency of occurrence
of different values of illumination. Such curves have the advantage of being in some
REPORT. - • vi
degree an indication of the actual conditions which experience has shown to be
necessary. In the case of foundries, for instance, there will be some rooms where
the illumination attained is very high, and others where it is exceptionally low, but
the question then arises how do they tend to group themselves between these extremes 2
To investigate this we arrange the observations in groups, each group containing
all those falling within certain selected limits. Then by taking a horizontal scale to
represent illumination, and a vertical one to represent the number of observations in
each group, we can plot on the diagram a number of points which in most cases lie on
a fairly smooth curve. The area of a portion of this curve bounded by two vertical
lines or ordinates drawn to correspond with any two illuminations will represent the
number of observations of illumination lying between these two limiting values, and
the curve thus indicates the manner in which the illuminations observed are
distributed among the places examined. One ordinate can be drawn to divide the
curve into two equal areas, and the observation points into two corresponding groups.
The number of observation points in each group is the same. In the one group of
factories each observation point has an illumination less than that corresponding to
this ordinate, in the other, greater. The point from which this ordinate is drawn
is denoted the mid-point of the curve, and it is to this mid-point we wish to draw
attention. The general shape of the curve should also be noticed. If a curve slopes
gradually from its maximum ordinate towards the right, the number of factories having
a higher illumination than that most commonly found is considerable ; if on the other
hand it falls sharply away, the illumination found in the larger number of factories is
seldom exceeded. Further details are given in Appendix XV.
5. DAYLIGHT FACTOR.—If it were possible to remove the walls and roof of a building
and so allow the full amount of light from an unobstructed sky to reach a given point,
the illumination there would have a very much enhanced value. The ratio of the
actual value of the illumination to this enhanced value, expressed as a percentage, is
termed the daylight factor, and is a measure of the lighting efficiency of the building
at the point under consideration. Compared with the variations of the outside
illumination, the daylight factor may be regarded as roughly constant for any point
in a factory, and mainly depends on the window area which is effective in admitting
light to the point in question. The term is fully discussed in Appendix XV.
FACTORS IN GOOD LIGHTING.
The first requisite for good lighting is that it should be adequate." In addition
to this it must be suitable for the purpose for which it is required. We may
summarise the factors which contribute to a good system, thus:—
(1) Adequacy. -
(2) A reasonable degree of constancy and uniformity of illumination Over the
necessary area of work.” -
(3) The placing or shading of sources so that the light from them does not fall
directly on the eye of an operative when engaged in his work, or when
looking horizontally across the workroom.”
(4) The placing of lights so as to avoid the casting of extraneous shadows on the
work.4 *
All these factors are undoubtedly of great importance, and we are of Opinion that
they should receive special attention in the design of lighting installations. We think,
however, that attention must be directed in the first place to the adequacy of the
illumination in factories and workshops, and both the measurements which have been
made in factories and the recommendations put forward in this Report are concerned
almost entirely with this aspect of the matter.
EXISTING REQUIREMENTS AS TO LIGHTING.
A.—STATUTORY.
For the United Kingdom no general provisions in respect of lighting (analogous
to those regarding temperature and ventilation) occur in the Factory Acts. The Only
reference to the subject is found in the Factory Act of 1901, section 101 (4), which
1 Throughout this Report the words adequate and adequacy are used in their quantitative sense, that is, .
they refer only to the amount of illumination. *
* Minutes of Evidence (Ritchie), qq. 1190–3. -
3 Ibid. (Wheat), 226–235; (Stokes), qq. 698–9; (Trotter), qq. 835–6; (Harrison), qq. 1006, 1050;
(Mackinney), qq. 1068–70 : (Thorp), qq. 1050–1 ; (Edridge-Green), qq. 21.17–8; (Cross), qq. 2598–9 ;
(Smalley), qq. 1995–2000. - -
4 Ibid. (Williams), q. 449; (Hine), qq. 887–93; (Wilson), qq. 1143–5; (Clark), qq. 201, 210–4;
(Wheat), qq. 243-4; (Whyte), q. 2761 : (Carr), q. 1754; (Hartshorn), qq. 2251–3. -
vii DEPARTMENTAL COMMITTEE ON TIGHTING IN FACTORIES AND WORKSHOPS :
specifies “adequate lighting ” amongst the conditions as to which a local authority must
be satisfied before an underground bakehouse is certified as suitable for use.
Under section 79 of the Act of 1901, the Secretary of State has power to make
regulations for certain trades certified by him to be dangerous. These regulations,
after conforming to a certain procedure, eventually attain the force of statutory
enactments. Some 20 codes of regulations exist, and of these five (namely, those
relating to— -
Docks, -
Use of locomotives, &c., on premises under the Factory Acts,
Vitreous enamelling of metal and glass,
Generation, &c., of electrical energy, and
Manufacture and decoration of pottery), -
contain provisions requiring adequate lighting in general terms for certain processes.
Finally, adequate lighting is required in two Special Orders made by the
Secretary of State (namely, those relating to Fruit Preserving and to Sanitary
Accommodation). -
The different requirements referred to are given in full in Appendix VII.
In order to obtain information as to the position in foreign countries, inquiry
was made through the Foreign Office as to the requirements in force in Austria,
Belgium, Denmark, France, Germany, Holland, Italy, Norway, Sweden, and the United
States of America. The replies received are summarised in Appendix VIII. It will
be seen that adequate lighting in general terms is required in the codes of all the
European countries mentioned, and in most of those of the United States, either by
legislation or by statutory regulations. For local lighting in certain trades definite
standards are prescribed in Holland only, whilst a provision against excessive glare
is found in the Belgian code.
Since these inquiries were made, it has been brought to our notice that a
provision, giving the Inspector power to require adequate lighting in factories, exists
in the Indian Factory Act of 1911, and that a definite standard for the general
lighting of factories is now in force in New South Wales.
In the course of the evidence given before us, attention has been called to two
existing requirements which, though not directly concerned with lighting, have
On Occasions led to some difficulty in regard to admission of adequate daylight to
factory premises. - +
The London Building Act of 1894, and also the building regulations of many
provincial authorities, limit the amount of window space in laterally lighted rooms
to one half of the total wall space. It has been represented to us that this unnecessarily
interferes with the natural lighting of the building,” and in one instance we were
informed that the wall space was actually artificially increased by the addition of a
parapet in Order that a larger window area might be available.” t
The other requirement which has led to some difficulty in administration occurs
i. the regulations for cotton cloth factories, in which it is provided (Regulation 8)
that— -
In every humid shed and in every dry shed the whole of the outside of the roof (windows
ereepted) and the inside surface of the glass of the roof-windows shall be whitewashed every year
before the 31st May, and the whitewash shall be effectively maintained till the 15th of September.
Provided that the above requirements of this Regulation, so far as regards roof-windows, nay
be suspended by certificate in writing from the Inspector of the District, if it is shown to his satis-
faction that the roof-windows are so placed, or are so shaded by adjacent buildings, that the direct
rays of the sun can never impinge upon them at any time during any day; which certificate shall be
Åept attached to the General Register.
- e º ! ~~4 ---|-- e ſº gº &
It has been brought to our notice' that whilst the proviso is obviously intended
to cover instances where, the whitewashing of the windows might involve seriously
decreased illumination, there are causes other than the presence of adjacent buildings
(such as the existence of heavy harness on the looms), owing to which light is already
obstructed to such an extent that any further loss due to whitewashing would lead
to the use of artificial lighting during the summer months. In many instances, also,
difficulty has arisen in the weaving of very dark-coloured materials, which, even in
summer, requires all available illumination on dark days.
smººt * *-
* 57 and 58 Vict., ch. ccxiii, s. 54.
* Minutes of Evidence (Siemens), q. 1290 ; (Owen), q. 3371 ; (Dewrance), qq. 3123.5.
* Ibid (Dewrance) q. 3132. * Ibud (Bellhouse) qq. 88–95; (Taylor) qq. 1521–7.
REPORT. - viii
These questions are outside our terms of reference, but we direct attention
to them in the hope that the authorities responsible for the administration of them
may take these points into consideration.
B.—OFFICIAL.
. The regulations issued by the Board of Education relating to the construction of
primary and Secondary school-buildings prescribe amongst other things adequate
window space (one-fifth of the floor area for class rooms), suitably placed windows, and
light coloured walls." Similar and, in some instances, more detailed requirements
are in force in most of the foreign countries of which inquiry has been made.”
The construction of workhouses and other buildings under the control of the
Local Government Board is subject to special instructions issued by the Board, in
which adequate window space is one of the points to which attention is drawn.
The building byelaws adopted by many local authorities, though not specifically
mentioning the question of lighting, often require that in new buildings every
habitable room shall have at least one window, and that the total window area shall
amount to at least one-tenth of the floor area. .
Finally, section 17 (7) of the Housing, Town Planning, &c., Act of 1909, empowers
local authorities to make regulations for underground rooms habitually used as
sleeping-places. A draft of such regulations, which is now issued to local authorities
for consideration, contains, we are informed, specific references to the lighting of such
rooms, requiring a window area of at least one-eighth of the floor area, and defining
the amount of permissible obstruction of the windows.
PRESENT LIGHTING OF FACTORIES.
A.—NATURAL LIGHTING.
The natural lighting of buildings may be derived either from the roof (roof or top
lighting), or from side windows (lateral lighting), or from both combined.
Roof lighting is obviously only available either in single storied buildings or on
the top floor of a block. It is the method commonly adopted where land is not a
serious consideration, or where the very heavy nature of the work carried on precludes
the erection of a second storey (as in large engineering works), or where uniform and
strong illumination is essential (as in weaving sheds). It varies in degree from a few
Small skylights (as in some of the letterpress printing works and small tailors'
workshops visited) to the “saw-tooth '' type of roof almost universal in weaving sheds.
In some modern shops of large engineering works the whole of the roof and a large
part of the walls as well are often constructed of glass in steel frames. With a good
system of roof lighting the illumination is very uniform, and may vary from 2 to 10 per
cent. of the outside unobstructed illumination. - - .
The large extent of glass surface sometimes makes it difficult to maintain an
equable temperature, and whitewashing the glass to keep out the direct rays of the
sun is largely practised in summer, whilst extra means of heating are provided for
use in winter. º
Lateral lighting is found in buildings of two or more stories, and the most typical
instances of its use are to be seen in cotton spinning mills. Here the illumination
is less important than in weaving, and the yarns being in the vertical position, the
work is well adapted for light coming from a horizontal direction. In most trades,
however, the working plane is horizontal, and lateral lighting must be considered
inferior to top lighting. |
In modern factories dependent mainly on lateral lighting, a large part of the wall
surface (amounting in the case of the newest methods of construction to 60 per cent.)
is occupied by windows, but it is evident that there is a limit in the width of room
(for a given height) beyond which the illumination falls below what can be considered
adequate.” * *
The want of uniformity is a further drawback to this method of lighting. Parts
of the room near to the windows may be very well lighted, while the interior of the
room may need permanent artificial illumination.
1 Appendix VII. & * Appendix VIII. * Minutes of Evidence (Solomon), q. 3261.
ix DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
B.—ARTIFICIAL TIGHTING.
The conditions of artificial lighting vary so much according to the nature of the
work that it is impossible to give here more than a very general statement. It is
agreed on all sides' that the artificial lighting of factories and workshops has
greatly improved during recent years, and in the case of the more progressive firms,
by whom the increase in efficiency due to better lighting conditions is recognised,
usually leaves little or nothing to be desired. Generally speaking, it may be said that
in well-equipped factories good lighting is provided where it is required for the
actual process of manufacture. Complaints have, however, been made of inadequate
illumination in some trades where fine work is carried on (drawing-in and twisting,”
tailoring, and sewing,” and lace-making"). Instances have also been brought to our
notice, both on visits to works and in evidence, where glare and shadows result from the
unsuitable placing of the light sources. Insufficient illumination is more commonly
met with in the general lighting of premises, or in the lighting intended to serve
for gangways, passages, &c. (as in foundries,” stairways and passages in cotton
mills,”) and we are of opinion that the conditions in many of these places are capable
of much improvement. - *
For sources of light, incandescent gas and electric light are now far the most
widely used, though mercurial vapour and other lamps are occasionally found, and in
isolated districts oil or petrol air gas installations are often adopted.
CAUSES OF UNSATISFACTORY ILLUMINATION.
A.—NATURAL LIGHTING.
While our inquiry has shown that there has been a general advance in matters of
illumination, many instances of work-rooms with poor natural lighting have been
brought to our notice, both by personal inspection and by the evidence of witnesses. .
The reasons may be classified under a few headings, and it is worthy of remark
that some of these may be remedied without much difficulty.
1. Old and Unsuitable Buildings.--In striking contrast with most modern factories,
which are usually excellently lighted, many instances have been noticed of unsuitable
buildings, originally intended for dwelling-houses or for some other purpose, used as
factories and workshops. In these the window area is generally deficient, and the
windows are not carried up to the ceiling. Similar considerations often apply to old
and out-of-date factory premises. - -
Underground workrooms, again, are frequently poorly lighted, and in some
instances are subject to the continuous use of artificial illuminants. No legislative
restriction appears to be placed on the use of these premises for industrial purposes
however unsuitable they may be, with the single exception of underground bakehouses
(Factory Act, 1901, s. 101 (4)). The whole question is referred to again later (p. x.).
2. Obstruction of Light.—Obstruction of light may be either external or
internal.
The former is generally due to the near presence of another building, and can be
rectified to some extent if the obstructing surface be whitewashed or by the adoption
of special reflectors and glass.
Amongst the internal causes is the temporary storage of materials or finished
articles near the windows, particularly in laterally lighted rooms in which bulky
articles, such as boxes, are made, or in which packing is done. In some cases
much could be done to improve the lighting by storing the articles in such a way
as to keep the windows as clear as possible. In top lighted rooms obstruction may arise
from high machines, and is always present in weaving sheds containing Jacquard looms.
3. Dirty Windows.-These are a very common cause of insufficient illumination.
By many firms this is fully recognised, and arrangements are made for periodical
cleaning. It will be seen that recommendations are made on this point (p. xviii.)
4. Dirty Walls and Ceilings.-These are frequently noticeable in foundries and
other factories where the nature of the work involves the production of smoke or
dust. Owing to the decrease in reflecting power, light is needlessly lost, and this
* Minutes of Evidence (Bellhouse), q. 485 (Williams), qq. 451-3 ; (Squire), g. 601 ; (Wheat),
qq. 222–4; (Stokes), q. 660; (Harrison), q. 1038 : (Thorp), qq. 1415, 1487; (Gass), qq. 2951–4 :
(Solomon), qq. 3325–7 : (Owen), qq. 3377, 3401 : (Symonds), g. 1689; (Hughes), q. 1918; (Allen), q. 2304;
(Shaw), q. 1535. * Ibid. (Bellhouse), qq. 61-70; (Robinson), qq. 1619–20.
* Ibid. (Squire), qq. 566–80; (Trebateoff'), qq. 1377–81 ; (tailors), q.7. 3073, &c.
* Ibid. (Wardle), qq. 22.12–2222. . " Ibid. (Bellhouse), q. 115; (Hutchison), qq. 1648, 1669–71;
(Lockyear), q. 2160. * Ibid. (Bellhouse), q. 30 ; (Taylor), q. 1515.
REPORT. . x
effect is especially marked in factories lighted from saw-tooth roofs, where much of the
light entering the windows is reflected from the sloping ceiling down on to the work.
The effect of light coloured walls and white ceilings on the general brightness of
the room and in affording an effective background to dark objects is often overlooked,
and we desire therefore to direct special attention to this means of increasing the
illumination in workrooms at a minimum of expense.
It will be seen that some of the causes mentioned above, namely (1) and to
some extent (2), which are especially noticeable in large towns where space is limited,
cannot be entirely removed without very drastic measures. The remaining causes of
unsatisfactory lighting could, however, be remedied without difficulty.
If daylight is insufficient, it can be supplemented by artificial light, although it has
been suggested that a mixture of the two is less satisfactory than either alone. There
is, however, the question of the hygienic importance of daylight as distinguished from
artificial light. In some minor branches of industry, for instance in the manufacture
and use of photographic materials, daylight has to be excluded altogether, and in
mining it is unattainable. It is, however, not uncommon to find artificial light used
continuously in workrooms to which these reasons do not apply, and the chief causes
for this have been already stated (p. ix). We have failed to obtain any definite evidence
of direct injury to health resulting from such conditions, and on the contrary statistics
have been produced tending to show that in one large factory the sickness rate
was actually lower in a room in which artificial light is nearly always needed, than
in another room well supplied with daylight, in which similar work was carried on
by persons of practically the same age and sex distribution. Nevertheless, we have
found substantial consensus of Opinion among witnesses of all classes, that conditions
involving the continuous use of artificial light are unnatural and entail greater
strain on the workers. In this view we concur. -
The question is however very complex. Where there is external obstruction,
the amount of daylight admitted diminishes (with equal window space) on each storey
as we descend, and is therefore at a minimum in basement rooms. If the excavated
area which such a room faces is so narrow as to reduce further the angle at which
the sky is visible, there is additional interference with daylight illumination, just as
there would be in a ground-floor room obstructed by a boundary wall of corresponding
height and nearness; but if the area be wide, there is not necessarily much more
difference, so far as adequacy of daylight is concerned, between the basement and
the ground floor than between the ground floor and the first floor. There are, of
course, other considerations, hardly within our province, to be taken into account with
regard to basement rooms. -
It has to be remembered that a room originally well supplied with daylight may
subsequently be darkened by conditions beyond the owner's or Occupier's control, for
instance the erection of obstructive buildings opposite to it, and, further, that the
distribution of daylight in different parts of a given room is dependent not only on
position in relation to the window, but also upon internal obstruction by machinery, &c.
On the other hand, there are many devices by which additional daylight may be
secured, and in overshadowed rooms the fullest use ought to be made of these,
thus:— - -
(1) The windows should be of adequate size and extend to as near the ceiling as
practicable.
(2) They should be kept clean, and free from unnecessary obstruction within.
(3) Vertical light can be deflected into the room by means of reflectors or prismatic
glass.
(4) It may be possible to whiten the surface of an external wall or building which
obstructs the light. -
(5) The inside walls and ceiling should be white or nearly white.
(6) The positions of the permanent working points should be so adjusted in
relation to the windows and to internal obstructions of whatever kind
as to secure as far as practicable adequate daylight for each.
It is obvious that the greater the fraction of outside light admitted, the later will
artificial light be required in the evening and the earlier will it be dispensed with in
the morning. Some indication as to the effect on lighting up time of the standard
proposed for workroom floors can be deduced from the data given in the Appendices.
For instance, from Appendix XV., curve C of Fig. 1, or line 3 of Table 1, it will
xi DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
be seen that for the floors of factories with roof-lighting the mid-point corresponds
with a daylight factor of approximately 2 per cent. Now the statement that a
room has a daylight factor of 2 per cent. means that its illumination is 2 per cent.
of that outside the factory (see p. vi.), Hence if the illumination inside the room
is not to be less than 0° 5 foot-candle, artificial light must be put on, when the
illumination outside is not less than 25 foot-candles. By reference to Appendix
XVI., it will be seen that on the average there is an illumination of 25 foot-candles at
sunrise and Sunset, and these, therefore, represent the proper daylight limits for
such a room, so far as the “general ” illumination at the point in question is concerned.
There are no easy means of solving the question what is the minimum amount of
daylight in which operatives should be allowed to work continuously. The ordinary
conventions, in terms of the ratio of window area to floor space, fail to take all
the conditions into account ; and in view of the inconstancy of the intensity of
daylight, a standard, in terms of foot-candles, would be unsuitable. It appears
possible that the use of the “ daylight factor’’ explained on page vi may help in
meeting the difficulty of determining upon a standard, but we desire to reserve
the consideration of this point for a future Report.
B.--ARTIFICIAL LIGHTING.
For artificial lighting also, the chief causes of unsatisfactory illumination may be
classified under a few headings.
1. The Provision of too few or too weak Light Sources.—This has been noticed on
some occasions, chiefly in the general lighting of large engineering works, foundries,
gangways and passages. Other instances where the illumination should be increased
by the supply of additional light sources have been brought to our notice in regard to
tailoring," drawing-in and twisting,” lace-making,” and hosiery-making.4
2. Antiquated Methods of Lighting.—As a rule the methods of lighting adopted,
(such as flame arcs, inverted incandescent and high-pressure gas, and metal filament
electric lamps), are modern and efficient, but instances are still found of the use
of antiquated systems which can only be justified in special circumstances. In some
engineering processes, for instance (e.g., work on boring machines and power hammers),
gas jets are still commonly employed on account of the rough usage to which the
local light sources are necessarily subject, but apart from these special instances they
are objectionable in many ways; they vitiate the air to an unnecessary extent, are
liable to flicker, and are so uneconomical that the small capital outlay required to
replace them by a modern System is rapidly repaid by the greater efficiency and
diminution in the running expenses. -
3. Inadequate Supply.—Complaints have been received of inadequate illumination
caused by the diminished pressure in the gas mains during the period of maximum
consumption,” and, where the electrical energy is generated on the premises, by the
installation of a dynamo or engine of insufficient output."
4. Neglect of Upkeep.–Considerable loss of light may result from deterioration of
gas mantles and filament lamps and from the deposition of dust. Systematic
attention to the light sources, therefore, is always necessary in order to obtain
maximum efficiency. w . *
5. Inside Obstruction.—This is less noticeable in artificial than in natural lighting,
since in the former there is wider choice in the placing of the light sources. It may
occur, however, in factories, where large and complicated machines (such as Jacquard
looms") are used, or where the sources are situated over a travelling crane or other
obstruction, as in Some foundries”. Some cranes have affixed to their under surface
lamps which travel with them, and considerable improvement would result, if this
method could be adopted more generally,
6. Shadows and placing of Lights.-Loss of light frequently arises from the sources
being so placed as to cause a shadow to be thrown on the work. This may be that of
the worker himself” or of some part of the machine (as in machine sewing"), or of
the material being worked upon (as in bootmaking" and tailoring”).
* Minutes of Evidence (Trebateoff'), qq. 1344–7; (Working tailors), q. 3078.
* Ibid. (Robinson), qq. 1604, 1625–8. * Ibid (Wardle), qq. 2191–9. 4 Ibid. (Hartshorn), qq. 2251–4.
* Ibid. (Squire), q. 588; (Taylor), qq. 1516–9; (Robinson), q. 1619.
- * Ibid. (Hutchison), q. 1649; (Wardle), q. 2213. 7 Ibid. (Shaw), q. 1553.
8 Ibid. (Williams), q. 449; (Wilson), q. 1145. * Ibid. (Hine), qq. 887–93; (Clark), q. 201;
(Hartshorn), qq. 2251-3 : (Thorpe), qq. 3636–7. " Ibid. (Whyte), q. 2761.
11 Ibid. (Whyte), qq. 2719–22. - * Ibid. (Trebateoff'), q. 1401.
REPORT. - xii.
EFFECTS OF UNSATISFACTORY ILLUMINATION.
1. Accidents.-The connection between lighting and incidence of accidents has
been investigated statistically, by means of a special return of all reported accidents
for 1913 and part of 1914, in which the number of accidents occurring each month
from different causes are separately tabulated according to industry. The full results
are given in Appendix TX., from which it appears that in respect of accidents due to
“ persons falling” (a cause which would seem to be specially dependent on lighting
conditions), the percentage to total accidents is higher during the period of the year
when artificial lighting is used than in the summer months. Further, by the use of
certain assumptions, it has been possible to calculate the probable accident rate per hour
separately for artificial and natural lighting. The results indicate that for most
industries the former is far higher than the latter, in some cases to the extent
of about 40 per cent.
Strictly speaking, these statistics only allow of a comparison between daylight
and artificial light and not between good and bad lighting of the same kind, but
inasmuch as natural lighting may be considered superior to artificial, so far at any
rate as regards liability to accident, it may be inferred that the same relationship
would hold between any methods of good and bad lighting. -
Further confirmation of the greater risk of accident during night was given in
the evidence of several witnesses. Thus, it was pointed out that the number of
accidents occurring in shipbuilding yards at night is quite Out of proportion to the
Small number of men employed'. Instances of accidents due to bad lighting
conditions were also given for foundries”, iron and steel works”, lace factories," and
cotton mills.”
In order to discover whether the connection between accident risk and lighting
conditions is generally recognised, inquiry was made of the Accidents Offices Association,
which embraces most of the Insurance Companies interested in Workmen's Compensa-
tion. In the reply of that Association it was stated that:—
“(a) the rates of premium charged by its members are based upon the assumption
“ that the lighting is normal; that if, upon survey, this is not found to
“ be so, the Insuring Company would specify its requirements or deal
“ with the case by rating; ”
“ (b) the effect of deficient or bad lighting upon a risk is distinctly prejudicial
“ in varying degrees from the accident point of view.”
2. Damage to EyeSight and Health.-Complaints as to eyestrain and headaches,
attributed to insufficient light, are common. Numerous references are also made to
discomfort and injury to the eyes caused by glare from light sources," but only in
a few instances (in watchmaking" and bleaching”) are these specific in character.
The unpleasant character of mixed natural and artificial light” has also been mentioned.
The prevalence of the use of spectacles amongst workers engaged in certain
processes (drawing-in and twisting", embroidery", brass wire weaving”, burling and
mending”, and tailoring*) has been brought forward as an indication of the bad
effects of these Occupations upon the eyes. Without thorough medical examination
of the eyes of large numbers of the workpeople engaged in these occupations,
and careful statistical correlation of the results, with due regard to age and other
conditions, it is impossible to draw definite conclusions from the evidence tendered,
though there can be little doubt that errors of refraction, &c., hitherto causing no
discomfort, may, apart from questions of illumination, lead to serious disability
when the individual is employed on work which makes great demands upon the
eyesight. - -
Special efforts have been made to obtain clear evidence of direct injury to
the eyes owing to bad conditions of illumination, and inquiry On this point was
addressed to the principal operative Associations concerned with fine work; the replies
received (Appendix XIII.) are, however, either negative or indefinite. It is well known
that serious injury accrues from exposure to very intense light, such as viewing an
* Minutes of Evidence. (Wilson), q. 1117. 3 Ibid. (Hutchison), q. 1659. “Ibid. (Wilson), qq. 1143–4.
* Ibid. (Wardle), 9.2200. * Ibid. (Heywood), q. 2796.
* Ibid. (Clark and How), qq. 168–76; (Wheat), q. 226 ; (Stokes), qq. 698–9; (Trotter), qq. 828–33;
(Edridge Green), qq. 2117–8. * Ibid. (Williams), qq. 526–33. * Ibid. (Smalley), qq. 1997–2000.
* Ibid. (Squire), g. 621 ; (Waldram), q. 2466; (Cross), qq. 2614–8. %
* Ibid. (Bellhouse), qq.6ſ–70; (Robinson), q. 1623. 11 Ibid. (Squire), q. 590.
* Ibid. (Wilson), q0. 1163–7. 13 Ibid. (Hughes), qq. 1932–40.
* Ibid. (Trebateoff), q. 1375; (Operative Tailor), qq. 3087–102.
xiii DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
eclipse of the sun with unprotected eyes, exposure to the flash of a short-circuit,
welding, glass-bottle making, and so on. We have had many general expressions
of opinion that insufficient light and excess of light, especially when accompanied
by glaring sources of light in the field of vision, are responsible for injury to the
eyes. Whilst it is doubtless true that such unsatisfactory conditions lead to mental
and physical strain, we have not received any concrete evidence of cases of actual
disease of the eyes. We are indebted especially to Mr. F. Richardson Cross, F.R.C.S.,
representing the Royal College of Surgeons, the Royal Society of Medicine, and the
Ophthalmological Society of the United Kingdom, for his very exhaustive inquiries
on behalf of the Committee amongst Ophthalmic surgeons on this aspect of the
question. A summary of the results of his inquiries, which, however, afford little
positive evidence, are given in Appendix XII. -
- 3. Insanitary Conditions.—The absence of sufficient light is detrimental in that
dirt is allowed to accumulate unnoticed." This aspect of good lighting is already
recognised in regard to fruit preserving factories and underground bakehouses in
which adequate illumination is required by law (Appendix VII.).
4. Diminished Output of Work.-The effect of improved lighting in increasing
both the quantity and the quality of the work is generally admitted, and specific
instances are quoted in the evidence. In One instance” the output was diminished
12 to 20 per cent. during the hours of artificial lighting, and in another” the earnings
of the workers increased 11° 4 per cent. after the installation of a better system
of lighting, and confirmatory evidence to that effect has been published in the United
States of America.” -
5. Lack of Discipline.—Good lighting is essential for proper supervision and
for the detection and prevention of idling.” Attention has also been directed by one
witness to the opportunities for immorality afforded by unlighted or badly lighted
yards, passages, and offices."
RECOMMENDATIONS.
In submitting our recommendations, we think it desirable briefly to review the
circumstances which in our opinion justify us in the proposals we are about to make
for the legal regulation of lighting in factories and workshops.
From the evidence taken by us, it is apparent that there is a general consensus of
opinion as to the economic and hygienic advantages of adequate and suitable lighting.
In support of this we would refer to Part E. of the Summary of Evidence (Vol. 2 of this
Report), from which it will be seen that H.M. Inspectors of Factories, the experts in
illumination, and the representatives of the scientific societies and of the employers'
and operatives' associations all agree as to the importance of good illumination and as
to the growing recognition of the fact. That this opinion is based on experience is
shown by the great improvement in industrial lighting which has taken place during
recent years and is still continuing." In the designing of modern factories, good
lighting (both natural and artificial) is now regarded as one of the most important
factors contributing to industrial efficiency.”
On the other hand, it must be admitted that many employers have lagged
behind in the general advance. This applies especially to old factories, designed
before the importance of illumination was generally recognised, and to small work-
shops, of which the Occupiers perhaps hesitate to expend the capital necessary for
improvement. -
It is obvious that any requirement which would tend to bring such places up to
the level of the more progressive firms would be beneficial, not only to the operative by
improving his working conditions, but also to the employer himself by increasing his
output. Light is a cheap commodity, and little or no hardship should result from
such a requirement, if gradually and sympathetically enforced.
Reference has been made already to the evil effects of unsatisfactory illumination.
It has been shown (p. xii.) that there is evidence of a relationship between accident
risk, and adequacy of lighting. Complaints as to damage to eyesight resulting
from bad lighting conditions are general in character and specific instances of injury
1 Minutes of Evidence (Williams), q. 450. * Ibid. (Wilson), q. 991. * Ibid (Ritchie), qq. 2340–7.
* Industrial Commission of Wisconsin ; Shop-lighting, 1st March 1914, pp, 6, 7. Compare also Journal
of Society of Arts, 7th Feb. 1913, p. 310. * Minutes of Evidence (Owen) q. 3377. -
* Ibid. (Squire), gq. 636–41. 7 Ibid. (Bellhouse), q. 53; (Williams), qq. 451–3; (Squire), q. 601.
* Ibid. (Waldram), q. 2455 ; (Solomon), qq. 3243, 3251 ; (Owen), q. 3382; (Hartley) q. 3491;
(Skull), q.3506–11; (Thorpe), q. 3604–5.
REPORT. - xiv.
are difficult to substantiate, but there is evidence of the existence of minor ailments
and general impairment of efficiency which must eventually re-act on the health of the
workers. -
There can be no doubt that the degree of comfort in the working conditions is
largely determined by the adequacy of the lighting. The visits paid to factories have
enabled us to realise not only the contrast between the depressing effect of dark
surroundings and the cheerfulness of a brightly illuminated workroom, but also the
vast difference in the working lives of the operatives that must result from continual
employment under the two conditions. This was made very clear during the experi-
ments with workpeople carried out at the National Physical Laboratory", and also in
the course of the observations in factories.
Finally, the necessity of prescribing adequate lighting in factories and workshops
has long been recognised abroad, and the industrial codes of all the principal countries
contain provisions requiring it in general terms. As has been already stated, definite
minimum standards for certain fine processes have been in force in Holland since 1895,
and in accordance with the progress of all matters connected with illumination, the
original values have recently (1911) been doubled. A minimum standard for general
illumination, also, is in force in New South Wales.” Several witnesses, some of whom
were opposed to the fixing of definite standards, agreed that the virtual omission
of any reference to lighting in the British Factory Acts is a serious defect.”
In view of these considerations, we feel justified in recommending that a require-
ment in general terms for adequate and suitable lighting be applied to all factories
and workshops. We are fully aware that until it is possible to define standards,
difficulties may arise from time to time in the enforcement of the requirement. Many
instances, however, have been brought to our notice, where, without the making of
any measurements, it was obvious that the illumination was “inadequate,” and a
general provision, such as that proposed, would seem to be essential for the
improvement of such conditions. -
Precedents for the making of such general provisions exist already in the
Factory Acts for temperature (Factory Act of 1901, section 6):—
(1) In every factory and workshop adequate measures must be taken for securing and maintaining
a reasonable temperature in each room in which any person is employed; but the measures so taken
must not interfere with the purity of the air of any room in which any person is employed.
(2) The Secretary of State may, by special order, direct, with respect to any class of factories
or workshops, that thermometers be provided, maintained, and kept in working order, in such place and
position as may be specified in the order.
and for ventilation (Ibid., section 7):—
(1) In every room in any factory or workshop sufficient means of ventilation shall be provided,
and sufficient ventilation shall be maintained. -
(2) The Secretary of State may, by special order, prescribe a standard of sufficient ventilation
for any class of factories or workshops, and that standard shall be observed in all factories and work-
shops of that class
In both of these sections, the requirements are expressed in general terms, and, in
the case of ventilation, the Secretary of State is empowered to prescribe a definite
standard for any class of factories or workshops. Now it is clear that in the case of
lighting, while it is possible to make a statutory provision in general terms as to its
suitability, it is impracticable to lay down in an Act definite standards as to the amount
of illumination required for various classes or parts of factories or for the numerous
processes carried on in them. The requirements applicable to each industry can only be
determined after careful enquiry. It is necessary, therefore, if standards are to be
established, to give to the Secretary of State power to prescribe these by Order, and
we recommend that this be done. -
It is realised that the analogy between temperature and ventilation on the one
hand, and lighting on the other, is not quite complete. In the first place, temperature,
and, to a less extent, ventilation can be expressed in terms, the significance of which
is generally understood, and in any given instance “adequacy” or “inadequacy” can
be defined by numerical values which are now generally accepted. In the case of
lighting on the other hand the unit of illumination, the foot-candle, although fully
established and of perfectly definite meaning, is an expression with which few are
familiar, with the consequence that in many instances the criterion of adequacy at
present consists merely of subjective impressions. -
* Appendix XIV. -
- 2 Full details of these requirements will be found in Appendix VIII.
3 Minutes of Evidence (Squire), q. 599; (Wilson), q. 1133; (Allen), q. 2303 : (Shaw), q. 1563.
a 30030 B
XV DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
Again, in the cases of temperature and ventilation, convection, and diffusion tend
to bring about a condition of approximate uniformity throughout the room ; illumina:
tion on the other hand has a characteristic value for each separate point and
diversity must constantly exist in the illumination at the different points in the room.
Broadly the illumination may be said to be adequate and suitable, provided that—
(a) it is sufficient for the proper carrying out of the work both as regards
quality and output, and - e tº
(b) there are no lighting conditions, prejudicial to the health, comfort and
safety of workers. -
In order to satisfy these conditions the lighting should comply with the four
requirements specified on page vi, namely:- -
(1) Adequacy. º © . . . .
(2) A reasonable degree of constancy and uniformity of illumination over the
necessary area of work. -
(3) The placing or shading of lamps so that the light from them does not fall
directly on the eyes of an operator when engaged on his work, or when
looking horizontally across the workroom. - - -
(4) The placing of lights so as to avoid the casting of extraneous shadows on the
work. . . -
We are of opinion that the general statutory requirement of “adequate and suitable
lighting” should include the observance of the last three conditions, in addition to the
provision of an adequate amount of illumination, and that power should be given to
secure compliance with them in cases where their neglect clearly renders the lighting
“inadequate and unsuitable '' in any of the particulars given above. Special
emphasis may be placed upon the avoidance of glare, of excessive contrast, and of
flickering lights.
As the conclusion then, of this part of our inquiry, we recommend that—
1. There should be a statutory provision— -
(a) requiring adequate and suitable lighting in general terms in every part of
a factory or workshop, and
(b) giving power to the Secretary of State to make Orders defining adequate
and suitable illumination for factories and workshops or for any parts
thereof or for any processes carried on therein.
STANDARDS OF ADEQUACY. —In view of part (b) of the above recommendations, we
have now to consider the question of the provisions to be embodied in such Orders.
We have seen that though the intensity of the light at the working plane is the most
important factor of adequacy and suitability, it is by no means the Only One, and in
making any Order the other factors must receive due weight. Even taking this
criterion alone, lighting requirements vary so much that each trade, or even each
process, must be considered on its merits, and a standard of anything like general
application is possible in well-defined circumstances only.
In cotton weaving," for example, the optimum illumination varies with the colour
of the yarn, the fineness of the yarn, the style of weave, and other circumstances, and
a single standard prescribed to cover cotton weaving generally would err in some
instances in the direction of prodigality, in others of insufficiency.
This aspect of the question has been touched upon in the course of their evidence
by many witnesses, who, whilst impressing on us the extreme difficulty of framing
a regulation to cover all the processes of their trades, agreed in thinking that there
might be some requirement specifying a minimum illumination for general lighting
to secure the prevention of accidents.”
A standard founded upon the numerical value of illumination deals with only
one aspect of the problem. It should be used, therefore, by the authorities as a
guide to the most important factor in adequate lighting rather than as an exhaustive
criterion. It is possible from this point of view to group working conditions in various
trades according to the minimum amount of illumination which may be regarded as
adequate. This can be done only empirically; and, as has been seen, a large
part of the work of the Committee has been devoted to obtaining for this purpose
data regarding a few selected trades, viz., clothing, engineering, and textile. The
results in full and also summarised are published separately.” The summaries
* Minutes of Evidence (Taylor), q9. 1504–19.
* Ibid. (Symonds), q. 1693, (Carr), q. 1735, (Russell), q. 1798.
* Stationery Office Publication.
REPORT. . xvi.
are also reproduced in Appendix XV, to this Report, and form, we believe, a
unique analysis of existing industrial lighting conditions. These observations allow
a judgment to be formed as to the average existing practice in this country, but for
the present, for reasons given elsewhere, we think it desirable to reserve any expression
of opinion as to the minimum amounts of illumination which are needed for special
processes. -
Leaving thus for the present the consideration of the illumination required for
special processes, we proceed to deal with the more general illumination of the factory
Or workshop as a whole under three heads:— * .
A. The illumination of workrooms or parts of workrooms where work is in
progress, that is, of the working area of the factory. •
B. The illumination of passages, stairways, lobbies, &c., and places in workrooms
or other parts in factory premises over which persons are liable to pass but
which are not parts of working areas.
C. The illumination of open yards and approaches.
By aworking area we understand that portion of the floor Occupied by, and
in the immediate neighbourhood of, the machines, benches, plant or material, at which
the operatives stand or sit in the execution of their work. In this area we include the
gangways and alleys between or around such working places.
A. Workrooms.--The methods of lighting of workrooms may be classified as
follows :- - t
(i) General lighting, whereby an illumination is produced which is approximately
uniform throughout the whole room ; - - . .
(ii) Localised general lighting, whereby an illumination is produced which is
approximately uniform over a portion or portions of the room in question ;
(iii) Local lighting, with the object of lighting some particular portion of a
machine or locality by an arrangement of individual lamps acting
independently of one another ; and
(iv) Combined local and general lighting.
Where general lighting alone is adopted, there is in most instances little risk of
the floor of the room being insufficiently illuminated, since the same light must serve
also for the carrying on of the work, but with localised general lighting there is always
some danger of parts of the room being neglected, whilst with strong local lighting,
the contrast between the brightly illuminated work and the comparatively dark
surroundings necessitates careful attention to the general lighting of the room.
Whatever be the light required for the work it is necessary that the working area
should be illuminated sufficiently for obstacles, dirt and waste to be clearly visible, whilst
in all industries, particularly those in which the work involves danger, it is essential
that the general illumination should be sufficient to avoid risk of accidents. Ample
illumination for the requirements of the work itself must be provided beyond the
minimum general illumination needed for these purposes.
Information as to the illumination in existing factories is given in the frequency
of occurrence curves for floors of workrooms (Appendix XV, Fig. 4). The mid-point, or
point above and below which an equal number of observations lie, is 0°45 foot-candle.
For the purpose of an order we have, however, to consider what may reasonably
be enforced as a statutory minimum, rather than what is now the average practice,
and having regard to this, we recommend that :—
2. Over the “working areas” of workrooms the illumination measured on a horizontal
plane at floor level shall be not less than 0°25 foot-candle, without prejudice to the
illumination required for the work itself. -
Our attention has been called to the special difficulties which would be caused if
a ship under construction or repair were considered for the purpose of this regulation
as part of the working area of a factory, and we desire, therefore, to reserve for future
consideration the question of the illumination to be provided on ships. Special
provision also will be necessary for certain workrooms, where the prescribed
illumination would interfere with the proper carrying out of some process, such as
the manufacture of photographic materials.
The lighting of iron foundries, was one of the points under discussion at a
conference held in January 1913,” but in view of the appointment of the present
* Minutes of Evidence (Wheat) q. 300. • - g
* Home Office Report on Conferences between Employers, Operatives, and Inspectors concerning
Safeguards for the Prevention of Accidents in Foundries, 1913.
- B 2
xvii DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
Committee, no decision was then arrived at. The question whether these should
be excluded from the above recommendation and made subject to a special standard
has received consideration. It appears to be true that the illumination in these
foundries is at present below the average of other workrooms. For this there is
no justification; on the contrary, the dark surroundings and want of contrast in
iron foundries indicate the desirability of specially good lighting, and we are of
opinion that a minimum illumination of 0.25 foot-candle is not sufficient for safety.
We accordingly recommend that :-
3. In all parts of iron foundries in which work is carried on or over which any person
is ordinarily liable to pass, the illumination measured on a horizontal plane at floor
level shall be not less than 0°4 foot-candle,
B. Passages, Stairways, Lobbies, &c.—For the satisfactory lighting of these, a
lower illumination will suffice than in the case of workrooms, since obstacles are
usually absent and the eye is not subjected to the same degree of contrast. Never-
theless, in the course of visits to factories, many instances of defective lighting
were noticed, and complaints were received from witnesses on this point, especially
in reference to cotton mills." The experience gained from visits to factories and
such observations as we have been able to make, together with the evidence brought
before us, indicate that it is desirable to adopt for these places a standard of not less
than 0-1 foot-candle. Instances requiring special latitude (such as long passages
free from turns and abrupt changes of level, and adequately lighted by the “beacon’’
system") may be dealt with under recommendation 6.” We accordingly recommend
that :– -
4. In all parts of factories and workshops (not included under recommendation 2)
over which persons employed are liable to pass, the illumination measured on a
horizontal plane at floor level shall be not less than 0-1 foot-candle.
C. Open Yards and Approaches.—Here the object of the lighting is to enable
a person to see sufficiently well not to stray from the path, and may be compared with
that of streets. For any locality where persons are employed at night, and for a path
or road, to which it is necessary to keep, in order to avoid danger (such as an approach
leading through a yard containing obstacles), we are of opinion that a minimum
illumination equivalent to that of a fairly well lighted side street, (0.05 foot-candle),
will be sufficient.
Approaches over clear ground (free from projecting rails or other obstacles and
from steps or other abrupt changes of level) where momentary straying from the path
involves no risk, and also fenced-in roads, can be adequately lighted by the “beacon.”
system, namely, the spacing of light sources along the direction of the path at such
long intervals that they serve as beacons or guides rather than means of illumination.
These would not be “dangerous parts '' in the intended sense of the next paragraph.
In docks, both places of employment and approaches are already subject to
a requirement for adequate lighting in general terms (Regulations for Docks, Reg. 3).
We recommend, in accordance with this precedent, that :—
5. In all open places in which persons are employed during the period between one
hour after sunset and one hour before sunrise, and in any dangerous parts of the
regular road or way over a yard or other space forming the approach to any place of
work, the illumination on a horizontal plane at ground level shall be not less than
0-05 foot candle.
- We desire to reserve for a future Report the case of shipbuilding yards, which
require special consideration and to which we have not yet been able to devote
attention.
ExEMPTIONS.–In order to meet exceptional circumstances in which the standards
proposed in recommendations 2, 3, 4, and 5 might cause hardship, we recommend
that :— .
6. There shall be power for the Department to allow exemption in individual
Ca,S6S, - - - -.
Under recommendation 2, for instance, exemptions might be permitted in the case
of little-frequented areas which would otherwise come under the designation of
working areas. -
* Minutes of Evidence (Taylor), qq. 1502–1516, (Shaw); qq. 1529–1602.
* For the meaning of this term, see below under (c).
* It may be remarked that a simple and inexpensive method of making steps more easily discernible is
- to mark their edges in white. - 2.
REPORT. - . . . . xviii
é CLEANLINESS OF WINDows.--It has already been stated that a very common defect
in factories is the dirtiness of the windows. Not only is a large proportion of daylight
prevented hereby from entering the room, but the daylight period of work is
considerably shortened and needless expense is incurred by the necessity of lighting
up earlier. -
Indirectly this will be controlled to some extent by the necessity of observing
the minimum standard of illumination, but we are of opinion that in ordinary work-
rooms any additional light which can be secured by such simple means as cleaning
windows ought to be supplied, and that there should be a direct obligation to that
effect. In rooms which have but little margin above the minimum, compliance with
it will depend upon attention to window-cleaning. We recommend the following
general provision :-
7. All external windows of every workroom shall be kept clean, on both the inner
and outer surfaces,
but in order to meet exceptional cases as below, there should be power to substitute
for the above a definite and binding scheme for cleaning the windows at reasonable
fixed intervals, where for example—
(a) the windows, or some of them (e.g., roof windows), are not readily accessible;
OI’ - - -
(b) the total surface of external windows is exceptionally large in relation to
the floor space; or
(c) the conditions of work are such that compliance with the ordinary requirement
is, in consequence of the nature of the work, impossible.
We suggest that the exemption should be allowed by certificate, entered in the
General Register. This follows the precedent in the Cotton Cloth Factories Regula-
tions (Reg. 8).
The requirement would not, of course, be held to debar any necessary white-
washing of windows such as is required by the Cotton Cloth Factories Regulations.
CONCLUSION.
In submitting these recommendations we realise that the standards proposed by us
appear to be lower than the values put forward' by various lighting experts who
have given evidence before us. Some of the latter referred to the general illumination
at the working level, where the values are naturally higher than at the floor
level, and in any case we have felt that they were intended as an indication
of ideal conditions, whereas it has been our object to suggest numerical values that
can be adopted as a practical legal minimum without causing hardship. It
must be remembered that in view of the diversity of illumination which always
exists whatever the system of lighting, any minimum value will usually connote a very
much higher maximum and average, so that with a given minimum the efficiency
of the illumination depends to a large extent on this diversity. A workroom, for
instance, in which the illumination is uniform and has the value of only 0° 25 foot-
candle, may be regarded in most cases as very inadequately lighted. We desire,
therefore, to point out that none of the recommendations made by us is intended
to supersede the requirement of general adequacy and suitability, which, as already
explained on p. xv, depend on several factors in addition to the amount of illumination.
The evidence before us from witnesses and our own observations do not justify
us in drawing any distinction in the present recommendations between direct,
indirect or semi-indirect systems of lighting, or between systems which differ in the
colour composition of the light. We suggest, therefore, that the standards proposed
should be adopted irrespective of the type of lighting. Similarly, the evidence does
not justify us in discriminating between natural and artificial lighting, and in the
recommendations submitted by us, the standards are intended to apply equally to
both, that is to say, when the natural illumination falls below the limits proposed,
it must be supplemented or replaced by artificial illumination.
* Minutes of Evidence, (Clark and How), qq. 186–192, (Wheat), q. 306, (Stokes),
qq. 681, 688, (Whyte and Angus), qq. 2695–2705. -
a 30030 T} 3
xix DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
The more specific recommendations of this Report may be said, broadly, to deal
with the general lighting of factories and workshops, in other words, they have for
their object the maintenance in all workplaces of certain standards of illumination
primarily intended to ensure the personal safety of workpeople moving about the
premises. In the great majority of factories, however, the standards of general
lighting suggested here would be inadequate for the actual machines and work
benches where the various manufacturing processes are carried on, and local lighting
in addition is generally essential. As already mentioned, we are not prepared at
present to suggest values for the minimum illuminations which may be regarded as
adequate for special processes. - -
It was originally our intention to supplement the data already collected for the
clothing, engineering, and textile trades, and to extend our enquiries on similar
lines so as to include other industries. In view, however, of the present economic
disorganisation we think it desirable to submit an interim report of the work already
done and to await settled conditions before further prosecuting the Inquiry.
The data given in several of the appendices will help those engaged in designing
new factories and in examining the adequacy of lighting in existing buildings. At
present there are few collated data of this character available, and the desire not to
withhold them longer from publication is a further reason for the submission of a
preliminary Report at this stage.
We are greatly indebted to various firms and private individuals whose assistance
has been readily given, and we desire to express to all such our grateful thanks.
The value of the experimental results detailed in Appendix XV. is due in no
small degree to the care and skill bestowed on a difficult task by Messrs. J. W. T.
Walsh and G. F. Sedgwick, by whom the observations were made ; while the wide
knowledge of factory conditions possessed by our Secretary, Mr. D. R. Wilson, and
the experience in questions of photometry and other scientific matters dealt with, of
his colleague Mr. C. C. Paterson, have proved of the utmost value. We desire to
record Our keen sense of the importance of the services rendered by these gentlemen
and our cordial thanks for their very efficient help. ar -
We are, Sir,
Your obedient Servants,
R. T. GLAZEBROOK (Chairman).
L. GASTER.
J. HERBERT PARSONS.
C. S. SHERRINGTON.
W. C. D. WHETHAM.
ARTHUR WHITELEGGE.
D. R. WILSON
- } Joint Secretaries.
C. C. PATERSON
APPENDICEs.
APPENDICES.
B 4
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
:
8
9
10
II
12
13.
e
APPENDIX I.
WITNESSES EXAMINED.
1. Official,
G. BELLHouse, H.M. Superintending Inspector of Factories.
W. WILLIAMS, 55 33 »
J. A. HINE, 5 3 55 35
Miss R. E. SQUIRE, H.M. Senior Lady Inspector of Factories.
H. J. WILSON, H.M. Inspector of Factories.
H. KENWooD, Medical Officer of Health for Stoke Newington.
T. W. HEY wooD, Certifying Surgeon, Darwen.
2. Professional, Technical, and Scientific.
(a) ILLUMINATING ENGINEERING EXPERTS.
J. G. CLARK and How, Gas Light and Coke Company.
II. C. WHEAT, British Thomson-Houston Company.
ALBERT STOKES, South Metropolitan Gas Company.
A. P. TROTTER, Electrical Adviser, Board of Trade.
T. E. RITCHIE, Union Electric Company.
A. J. WHYTE and J. ANGUS, Keith-Blackman Company.
(b) REPRESENTATIVES OF PROFESSIONAL AND SCIENTIFIC SOCIETIES.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41
42
43
44.
45
46
47
48–
HAYDN HARRISON, Illuminating Engineering Society.
W. H. MACKINNEY, 55 35 35
J. S. DOW, - 3 3 35 33
A. SIEMENS, Institution of Electrical Engineers.
FRANKLIN THORP, Institution of Gas Engineers.
(c) ARCHITECTS AND SURVEYORs.
P. J. WALDRAM, Tuondon.
W. E. POTTS, Manchester.
J. B. GASS, Bolton.
TIEWIS SOLOMON, London.
SEGAR. Owen, Warrington.
H. HARTLEY, Liverpool . .
(d) MEDICAL.
F. W. EDRIDGE-GREEN, Ophthalmic Surgeon.
W. McDoug ALL, Physiologist.
F. R. CROSS, Ophthalmic Surgeon.
3. Representatives of Trade Associations.
(a) EMPLOYERs.
John TAYLOR, Cotton Spinners and Manufacturers.
H. L. SYMONDs, London Chamber of Commerce.
JOHN CARR, 33 35 33
S. A. RUSSELL, 33 35 93
W. A. HUGHES, Fine Cloth Manufacturers’ Association.
ROBERT KING, National Light Ironfounders’ Association.
JoHN ALLEN, National Federation of Merchant Tailors.
JOHN DEWRANCE, Engineering Employers’ Federation.
FRED SKULL, High Wycombe and District Chamber of Commerce.
WILLIAM ECCLES »; 35 35 53 5
THOMAS HARRISON THORPE, Derby Chamber of Commerce.
5
(b) OPERATIVEs.
R. TREBATCOFF and A. HILLMAN, Jewish Tailors', &c., Trade Union.
THOMAS SHAW, Amalgamated Weavers' Association.
W. C. ROBINSON, Beamers, Twisters, and Drawers’ Association.
A. HUTCHISON, National Union of Stove Grate Workers.
R. GIRVAN, Scottish Operative Tailors’ Association.
A. SMALLEY, Operative Bleachers’, &c., Association.
F LOCKYEAR, Ironfounders’ Society.
C. WARDLE, Operative Lacemakers’ Society.
W. HARTSHORN, National Hosiery Federation.
4. Miscellaneous.
50. Three working tailors.
APPENDICES.
APPENDIX II.
FACTORIES AND WORKSHOPS VISITED.
I.--TEXTILE FACTORIES,
A.—COTTON.
No. Firm. Address. Process.
1 | Barlow and Jones, Titd. gº - || Cobden Mill, Bolton - sº - Weaving.
2 55 9 3 . tºº - | Prospect Mill, Bolton - - - || Spinning.
3 Catlow, John, and Son * - Olive Mill, Darwen - * - | Weaving.
4. 2, 33 * - Sudell Side Mill, Darwen - * 2 3
5 32 53 gº - Rose Mill, Darwen - Jº- wº 55
| 6 || Croal Spinning Company - - || Dean Road, Bolton - * - Spinning. &
7 Crooke, Peter, Ltd. - £- - || Moorlands Mill, Bolton gº - 5 5
8 Dawson Bros. - sº tºº - Rathbone Street, Liverpool - - || Bag knitting.
9 Dewhurst, G. and R., Ltd. - - || Arkwright Mill, Preston - - || Spinning and weaving.
10 33 33 35 T - || Farington Mill, Leyland - - | Weaving.
11 || Horrockses and Crewdson & Co., || Moses Gate, Bolton - sº & 55
Ltd.
B.—FLAX.
12 || Falls Flax Spinning Company, Ltd. | Cupar Street, Belfast - tº- - || Weaving.
13 Greeves, J. and T. M., Ltd. - - || Forth River Mills, Belfast - - || Spinning.
14 || Jaffe Spinning Company, Ltd. - || Newtownards Road, Belfast tº 5 2
15 Johnston, Allen, and Sons, Ltd. • Lurgan sº tº . -* es - || Weaving.
16 || New Northern Spinning Company, Falls Road, Belfast - gº - || Spinning and weaving.
Ltd. - - * I , - - -
17 Watson, Valentine & Co., Ltd. - || Belfast - - * - - | Weaving.
C.—WOOLLEN AND WORSTED.
18 Crosthwaite & Co. . . . York street Mills, Leeds . . . spinning.
19 || Rogerson and Pinder - gº º 22 5 2. * $º 5 3
D.—OTHER.
20 Adams, Thos., & Co., Ltd. - - || Sherwood Rise, Nottingham - . Lace making.
21 Birkin & Co., Ltd. * sº - Broadway, Nottingham tºº sº 5 2
22 Cutts, T. B., & Co. sº {- - || Sims Factory, Nottingham - - 3 5
23 | Lee, A. H., and Son, Ltd. - - || Birkenhead - *g tº tºº - || Tapestry weaving.
24 Morley and Sons, Ltd. sºn - || Manvers Street, Nottingham - || Hosiery knitting.
II.-ENGINEERING WORKS, FOUNDRIES, &c.
No. Firm. Address.
25 Armstrong, Sir W. G., Whitworth, & Co., Ltd. - - | Elswick, Newcastle-on-Tyne.
26 Barr and Stroud - * sº tº- wº sº sº - Anniesland, Glasgow.
27 | Brown, John, & Co., Ltd. * wº & tº- - - || Atlas Works, Sheffield.
28 Cammell, Laird, & Co., Ltd. - º sº sº - | Tranmere, Birkenhead.
29 Craig, A. F., & Co., Ltd. tº - = ſº tº- - || Paisley. -
30 | Donkin & Co., Ltd. * º †º * * * - Shields Road, Newcastle-on-Tyne.
31 Hattersley Bros., Ltd. - * & sº - * - Swinton, Yorks.
32 Heaton Foundry Co. - sº gº * tº - Chapman Street, Newcastle-on-Tyne.
33 || Jessop, William, and Sons, Ltd. - tº- wº fº - Brightside Works, Sheffield.
34 || King, David, & Sons, Ltd. - - - es - - Possilpark, Glasgow.
35 | Siemens Bros. & Co., Ltd. - * $º gº º - || Woolwich, S.E.
36 | Stewart, D. J., & Co. - ſº e- tº tº sº - Charles Street, Glasgow.
37 Weir, J. and G., Titã. - s º tº * & - Cathcart, Glasgow.
38 Wilsons and Matthesons, Ltd. -: tº * tº - Armley, Leeds.
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
3. III–MAKING UP OF CLOTHING AND SIMILAR WORK.
A.—WHOLESALE CLOTHING.

No. Firm. Address.
39 Beatty Bros., Ltd. & wº gº * tºº sº - Church Street, Liverpool.
40 || Beatty Bros. (Manchester), Ltd. - & tºº wº - || Spear Street, Manchester.
41 || Beetles, W. C., & Co. - &º & º * us - | Tuittle Britain, London, E.C.
42 | Frankenburg, I., and Sons, Ltd. - s gº tº - | Salford, Manchester.
43 Tewis Bros., Ltd. - t- *- ſº - || Ranelagh Street, Liverpool.
44 Philips and Piper, Ltd. - & * dº º - || Tower Lane, Bristol.
45 Todd and Sons, Ltd. ſº & sº - || Bath Place, Bristol.
46 || Walsh & Co., Tutd. - *- wº. º, * * - || Nelson Street, Bristol.
47 Wills, Chas., and Sons, Ltd * sº sº tº - || Rupert Street, Bristol.
B.—TAILORING
48 Laidlaw and Procter - sº tº sº {- # = - St. Vincent Street, Glasgow.
49 | McArthur, J. and J. - <--> - || Paisley.
* * Five tailors' workshops -
- gº º, sº - | Whitechapel, London, E.
C.—HIEMSTITCHING!.
55 Glendinning, McLeish & Co., Ltd. - & & & - || Belfast.
56 || Hanna, H. B. tº-3 gº & sº Jºs * &= - Lurgan.
57 | Johnston, Allen and Sons, Ltd. • dº tº dº 32
58 || Mather and Bunting - gº * sº gº & 33
59 || Murphy and Stevenson - * sº #º * wº {-} 33
60 | Nelson, R., & Co. - gº. ſº es sº - Belfast.
D.—BOOT-MAKING.
61 | Headford and Frewin, Ltd. - & * - - || Portland Square, Bristol.
62 Mayo & Co., Ltd. - :- rºs * ſº- {-, * : * * 33 33 55
63 | Portland Boot Co. - tºº tº gº. * a 4- 33 35
IV.-MISCELLANEOUS INDUSTRIES.
No. Firm. Address. Industry.
64 || Bale, Son, and Danielson, Ltd. - || Great Titchfield Street, E.C. - | Letterpress printing.
65 Bennett, Wm. - sº & - Broad Street, Bristol - ſº * 39 93
66 Parry, John, & Co., Ltd. - - | Upper Thames Street, E.C. - fº 5 § 5 y
67 || Spottiswoode & Co., Ltd. - - | New Street Square, E.C. - ſº .33 5 *
68 Times Publishing Co., Ltd. - - | Printing House Square, E.C. * 35 35
69 United Newspapers, Ltd. - - || Salisbury Square, E.C. -*. gº 53 39
70 Smith and Young, Ltd. º - | Upper Thames Street, E.C. - - Copper engraving.
71 Waus and Crampton, Ltd. - - || Kirby Street, E.C. - - - | Process copper engraving
72 | Ingersoll, Robert H., and Brother | Audrey House, E.C. - - - || Watch assembling and re-
- palring.
73 | Whitehorn Bros. - º ſº - | Featherstone Buildings, E.C. - || Diamond setting.
74 Savory, E. W., & Co. - gº - Park Row, Bristol º gº - Christmas card making.
75 || Mordan, S., & Co., Ltd. wº - || City Road, E.C. - tº wº - || Pencil case making, &c.
76 Johns, Son, and Watts, Ltd. is 2 3 2 3 & tº sº - Fancy boxes.
77 | Mardon, Son, and Hall, Ltd. - Temple Gate, Bristol - º 55 55
78 || Fry, J. S., & Co., Ltd. - sº - Bristol tºs ſº ſº * . - || Chocolate and cocoa.
79 | Peek, Fream, & Co., Ltd. - - || Bermondsey, S.E. º $º - || Biscuit making.
80 || Indiar-rubber, Gutta-percha, and | Silvertown, E. - ſº * * - India-rubber working.
Telegraph Works Co., Ltd.
81 | Armstrong, Sir W. G., Whitworth, Walker, Newcastle-on-Tyne - | Shipbuilding.
& Co., Ltd. - - - -
82 London and Glasgow Engineering | Govan, Glasgow - {º ſº º 9 3
and Iron Shipbuilding Co., Ltd.
83 | Henderson, D. and W., Ltd. - Partick, Glasgow º g- tº »
84 || Barnscome, H., and Sons, Ltd. - || Eyre Street, Sheffield - ſº - Cutlery grinding.
85 Smith, C., and Sons, Ltd. - - Arundel Street, Sheffield - tº; 53 55
86 Rodgers, Joseph, and Sons, Ltd. - || Norfolk Street, Sheffield - - Cutlery making.

APPENDICES.
APPENDIX III.
CIRCULAR LETTER TO TRADE ASSOCIATIONs.
At the beginning of the inquiry the following letter was
addressed to 77 Trade Associations, from which
31 replies were received.
Eſome Office, Tuondon, S.W.
THE above Committee has been appointed by
the Secretary of State to inquire and report:-
As to the conditions necessary for the adequate and
suitable lighting (natural and artificial) of factories
and workshops, having regard to the nature of the
work carried on, the protection of the eyesight of
the persons employed, and the various forms of
illumination, *
SIR,
and is constituted as follows:–
Dr. R. T. Glazebrook, C.B., D.Sc., F.R.S., Director
of the National Physical Laboratory (Chairman).
Mr. Leon Gaster.
Mr. J. Herbert Parsons, M.B., D.Sc., F.R.C.S.
Professor C. S. Sherrington, M.D., F.R.S.
Mr. W. C. D. Whetham, F.R.S., and
Sir Arthur Whitelegge, K.C.B., Chief Inspector of
Factories.
We are instructed to ask you to be good enough to
bring the appointment of the Committee to the notice
of your Association and to invite them to consider
whether they can assist the work of the Committee
either by putting forward the names of witnesses who
would be prepared to tender evidence, or in other ways
by submitting questions regarding any phases of the
subject to which in their opinion the Committee should
direct special attention. -
As an indication of the kind of evidence required,
we are directed to invite the attention of your Associa-
tion to the following points:—
(a) The possibility of defining and establishing a-
standard or standards of adequate illumination
suitable for the various operations and processes
in the trade represented by your Association.
(b) The classification of processes in relation to the
illumination required. -
(c) The enumeration of the various processes in
which specially good illumination is desirable,
and information as to means of securing it.
(d) Examples of processes presenting special
difficulties in respect of efficient lighting, owing
to the relative positions of the work and of th
light sources, or for other reasons. -
(e) Particulars of the methods of illumination in
general use, with details of special systems which
have been adopted for special processes.
(f) The relative merits of daylight and artificial
illumination, and the extent to which the latter
is used, depending on the usual period of
employment in the industry represented by your
Association. -
For the present, the Committee are confining their
inquiry to a limited number of industries, and they
have addressed this letter to various Associations
representative of the industries concerned, and likely
to be interested in the questions to be investigated.
We are to add that the Committee would greatly
value your assistance in making the scope of their
inquiry known to the Societies affiliated to your
Association, with the object of inviting evidence from
persons in a position to assist the Committee in their
future work.
We are, &c.,
D. R. WILSON,
C. C. PATERSON,
tºp
Joint Secretaries.
APPENDIX IV.
APPROxIMATE NUMBER OF PERSONs EMPLOYED IN THE PRINCIPAL INDUSTRIES (1907).
TABLE A.—TEXTILE FACTORIES.
Persons employed (thousands).
. Principal Seat of
Young Persons p
Industry. * Adults. Total.
mclustry Chil- under 18. - Industry.
dren. -
M. F. M. F. M. | F. M. & F.
Cottom:— -
Spinning, &c. - - - || 7-6 25 4 || 37' 3 75 92 105 || 133 238 || Bolton, Oldham, &c.
Weaving, &c. - 3- - || 11 - 3 | 19 0 || 46 - 5 82 165 105 || 219 || 324 | Blackburn, Burnley, &c.
All processes - 3- - 19 . () 45 - 8 || 85 6 163 263 218 359 577 tºº-º-º-º-º:
Wool and worsted - -
Spinning, &c. - es - || 7.6 11-6 || 19.6 25 34 40 38 98 || Bradford, Halifax.
Weaving, &c. - & ºt 0 - 4 || 5 | 1 || 11 ° 9 35 67 41 79 120 Huddersfield, Rochdale.
All processes - Gº - || 8 - 1 | 19 4 || 33.9 85 114 || 109 | 152 261 !--ºmsºmº-
Silk:—
Spinning, &c. - º - || 0 | 7 || 1 | 1 || 2 5 3 7 3 9 14 || Macclesfield, Bradford.
Weaving, &c. - gº - || 0 - 0 || 0 | 4 || 2 | 0 3 8 3 10 13 ſº-ºmsºmº
All processes - tº - || 0 - 9 || 1 | 7 || 4 - 8 7 15 9 20 29 ſºmºsº,
I ace - sº $º - - || 0 | 1 || 2 | 0 || 2 - 5 11 6 13 8 21 | Nottingham, S.W. Scot-
. land.
Hosiery - * - - || 0 | 0 | I 5 || 8 - 7 8 22 10 30 40 | Nottingham, Leicester.
Carried forward - * |

6 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND worksHoPs :
Persons employed (thousands).
- º - Principal Seat of
Industry. Yººn Adults. Total. p
Chil- * Industry.
dren. -
M. F. M. F. M. F. M. & F.
Brought forward - -
Flax :—
Spinning, &c. - - tºº 3 - 9 || 4 - 7 || 8 6 10 24 17 35 62
|Weaving, &c. - gº - || 0:2 || 1 - 7 || 5.8 9 29 11 35 46 | North of Ireland.
All processes - sº - || 4 - 1 || 6’ 6 || 14-7 21 54 30 || 71 || 100 esse--w
Hemp — -
Spinning, &c. - º - || 0 | 0 || 1 | 0 || 1 4 2 5 3 7 10
Weaving, &c. - tº - || 0 - 0 || 0 | 0 || 0 - 0 O 0 O 0 0 Belfast, Glasgow.
All processes - º - || 0 | 0 || 1 - 0 || 1 : 5 3 6 4. 7 11
Jute :- - -
Spinning, &c. - & - || 0 | 3 || 2 | 1 || 2: 9 5 12 7. 15 22 . *=sººmsºn
Weaving, &c. - tº - || 0 | 0 || 0 | 3 || 1 - 4 3 11 3 12 15 | Dundee.
All processes - gº - || 0 | 3 || 2 | 6 || 4 - 4 T0 23 12 27 39 ****
Other industries - - - || 0-0 || 0-6 | 1.4 || 3 || 3 || 4 || 5 || 8 *º-º-º-º-º:
All industries - - - || 32' 6 81.8 157 || 311 505 | 407 | 680 | 1,087 —

TABLE B.—NoN-TEXTILE INDUSTRIES (FACTORIES AND WORKSHOPS) IN WHICH MoRE THAN
50,000 PERSONS ARE EMPLOYED.
Persons employed (Thousands).
. * ºf ººººº, - Principal Seat of
Industry. |*.*.*. Adults. Total. vasato many
Chil- g (if localised).
dren. -
M. F. | M. F. M. F. | M. & F.
*Engineering - - - || 0 | 4 || 68' 5 || 6’ 9 || 413 14 || 482 21 503 || Glasgow, Birmingham,
Manchester, Leeds.
Dress-making, millinery, &c. 0 5 || 1 | 1 || 79° 5 7 148 9 228 237 || London, &c.
Shipbuilding and marine || 0-0 || 22-6 || 0 1 174 1 197 1 198 || Newcastle, Glasgow,
engineering. - Sunderland, &c.
Tailoring - tºº gº - || 0 | 2 | 7' 0 || 22 - 4 53 | 68 61 91 | 152 | Leeds, Manchester.
Iron mills - & sº () - 0 | 13 - 4 | I 2 | 132 2 | 1.45 3 || 148 Sheffield, Newcastle,
Workington, &c.
Sawmills, &c. - gº - || 0 - 0 | 19 - 5 || 0 | 2 | 115 0 134 1 || 135 -
Printing, bleaching, dyeing - || 0 | 6 | 12'3 8:0 81 24 94 82 | 126 || Manchester, Bradford,
- . - - * - - I - North Ireland, Glas-
CROW,
Boots and shoes - - - || 0:2 | 16.7 | 12:9 | 67 || 26 | 84 || 39 123 | Northampton, Leicester.
Iron founding - sº - || 0 - 0 | 16. 6 || 0 - 7 || 103 | | 119 2 | 121 || Glasgow, Falkirk, Stock-
. - - ton, Leeds.
Letterpress printing - - || 0 - 1 18 - 5 || 6 - 1 80 11 99 17 | 1.16 -
Taundries - sº - - || 0 | 1 || 1 7 || 15 - 7 10 88 11 || 104 || 115
+Chemicals - gº º - || 0 - 2 7.8 6 - 5 87 14 94 21 115 St. Helens, Widnes,
London.
Baking of bread, biscuits, 0-4 13°4 14' 3 62 24 76 37 | 114 *msº
&c. - ~. -
Coach and wagon building - || 0 | 0 || 8 7 || 0:5 82 I 91 2 93 || Rotherham, &c.
Cabinet making and up- || 0 | 1 || 11 7 || 4-7 61 14 73 18 '92 || London.
holstery. . - -
China and earthenware - || 0 - 0 || 7 | 2 || 8 6 36 22 43 || 31 74 Stoke-on-Trent, &c.
Bricks and tiles . . . . 0-1 9-8 0-7 52 || 4 || 62 || 5 || 67 | Peterboro, &c.
Gas making tº fº - || 0-0 || 1-0 || 0-0 || 61 || – 62 || – 62
Brewing and distilling - | () - 0 || 1 | 9 || 0 - 1 49 — 51 — 51 Burton, Dublin, &c.
All industries - - - || 4 - 5 || 393 | 330 2,471 | 840 |2,868 1,172 |4,040



* This term is used in a very wide sense, and includes the manufacture of all kinds of machinery (except marine engines),
locomotives, cycles, and also electrical engineering. -
f This term includes the manufacture of products, in the making of which chemicals play a part, e.g., soap and candles,
ink, &c. - - -
APPENDICEs.
APPENDIX W.
SUMMARY OF REPORTS RECEIVED FROM H.M. INSPECTORS OF FACTORIES.
H.M. Inspectors were requested to forward notes
of any point that might be of use to the Committee,
e.g. :—
1. Processes requiring exceptionally good light,
by reason of the fineness of work, colour of
material, or other circumstance, and the arrange-
ments made to meet this ;
2. Processes in which there is exceptional exposure
to glare, and for what reason;
3. Processes in which the lighting is generally
inadequate, with detail of a few of the worst
examples met with ;
4. Examples of special means of lighting, or of
protection from glare, and their efficiency.
Reports were received from 30 districts (out of
a total of 51) and are summarised below.
1. PROCESSES REQUIRING EXCEPTIONALLY
GOOD LIGHT.
Industry and Process.
A.—On account of the Fineness of the Work.
Cotton cloth factories:—
Weaving coloured goods.
Jacquard weaving.
Drawing and twisting.
Linen weaving:—Examining and lapping.
Worsted and woollen weaving.—Examining, pick-
ing, mending, burling.
Silk throwing.
Trace making and mending.
Net lace break repairing.
Hosiery-making:—Linking up, running on, and
chevening (hand embroidery).
Letterpress printing:—
Type distributing.
Composing.
Machine ruling.
Engraving :-
Copper-plate.
Photo.
On glass.
Machine sewing:—
In wholesale tailoring, &c.
In hem-stitching factories.
Embroidery.
Engineering —Machine and fitting-shop processes.
Glass-making :-
Staining, engraving, cutting.
Optical glass-work, spectacles.
File-cutting by hand.
Brass wire weaving.
Needle-making —
Spitting (threading wire through eyes).
Straightening.
Jºye-punching.
Silversmiths' processes.
Button-making.
Jewellery and diamond-setting.
Clock- and watch-making.
Making of scientific, electrical, and surgical instru-
ments.
Electric glow-lamp making.
B.—On account of the Colour of the Material.
Black silk weaving.
Calico-printing.
Pottery-making:—
Transfer-making, painting.
Paint-mixing.
C.—To ensure Cleanliness and good Sanitary
Conditions,
Laundries.
Baking of bread and biscuits, confectionery, &c.
Wool-sorting and manipulation of dangerous wools
and hides (to enable deleterious substances to
be easily distinguished).
D.—For the Avoidance of Accidents.
Dry-cleaning (danger of fire).
Power-press processes (metal-box making).
Iron foundries.
2. PROCESSES IN WBICH THERE Is
EXCEPTIONAL EXPOSURE TO GLARE.
Industry and Process.
A.—Processes involving Manipulation of Molten or Hot
Metal or Glass.
Blast furnaces.
Iron mills.
Steel works.
Eorges.
Siemen's furnaces:
Oxy-acetylene welding and cutting.
Electrical welding (causing “welders’ rash” an
affection similar to “snow blindness”).
Glass works (“gathering” and “pipe blowing ”).
B.--Processes involving Ela'amination of Incandescent
Surfaces.
Gas works (retort houses).
Cement works (rotary kiln process).
Electric glow lamp works (sealing, testing).
Incandescent gas mantle factories (burning off).
Jewellery and vitreous enamelling (exposure of eye
to lining of muffle furnace).
Carbide of calcium furnaces.
C.–Processes in which Electrical Discharges take place.
Generation of electricity.
Testing of electrical apparatus, such as sparking
plugs for motors.
D.—Processes in which Glare is liable to be caused by
the Position of the Light Source.
Letterpress printing works (composing frames).
Wholesale tailoring (sewing machines).
Hemstitching (sewing machines).
Boot factories (various machines). *
Motor repair works (use of portable unshaded
lamps).
Photography by arc or flash light.
Hollow ware turning (the room is purposely
darkened and a lamp placed in the opening of the
ware, in such a position that the light source is
between the worker's eye and his work).
Silver and electro-plate works (burnishing, owing to
mirror reflection from the polished surface)
g
3. PROCESSES IN WHICH THE LIGHTING
IS OFTEN INADEQUATE,
Industry and Process.
Cotton-spinning mills:–
Blowing-rooms.
Waste breaking-rooms.
Passages, &c.
Woollen mills:—Teasing and scouring rooms.
Iron and tinplate mills.
Steel works.
IEngineering works:—Smiths' shops.
Metal stamping works.
Foundries.
Chain-making factories.
Shipbuilding and repairing yards, graving docks.
Glass bottle works. --
Drain pipe potteries.
8 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
Brickworks (especially press rooms).
Feeding-stuff mills.
Sawmills and flour mills (mill-gearing basements).
Underground bakehouses.
Photographic material factories.
Tailoring factories (local light).
Warehouses and stores.
Basement rooms in factories.
4. ExAMPLES OF SPECIAL MEANS OF LIGHTING
OR OF PROTECTION FROM GLARE.
Process. Method of Lighting.
Large white reflecting sur-
faces used as a background
for the wire.
Portable electric lamps pro-
vided to light part of the
surface being cut and to
eliminate shadow cast by
cylindrical cutter.
The light is high at the back
of the workers, and is re-
Drawing and covering of
fine copper wire.
Rotary milling cutters
in engineering works.
Assorting room of a
tin-house.
placed on wall in front of
Ił16I1. -
Ship repairing - - | Use of acetylene flare lamps.
Engraving and jewel-
lery.
Elastic hosiery works
(needle setting).
Use of “acid globes” for
concentrating light on
work.
flected from white sheets
Process. Method of Lighting.
Electro-plate works
(engraving and mark || Use of white tissue paper to
making). e tº
Needle factories | diffuse light.
(straightening).
This is carried on in front
of a window ; an opaque
screen is used to cut off
direct daylight from the
workers’ eyes.
Rooms artificially darkened
in order (a) to diminish
mirror reflection, and (b)
to enable the right tem-
perature to be noted.
Hosiery factories (needle
setting).
Electric plate works —
(a) Burnishing rooms
(b) Soldering rooms -
Spectacles of blue or smoked
glass used. In one glass
works special means of
Electric lamp works
Cement works (rotary
kiln process).
Glass works - nº |
º rotecting “gatherers ”
Oxy-acetylene cutting pro
Electrical welding 8:3 are adopted.
Miscellaneous - - Use of mercury vapour,
petrol, air gas, and high-
pressure gas systems, and
prismatic glass for day-
light noted in various
factories. -
APPENDIX VI.
MEMORANDUM on INVESTIGATIONS CARRIED OUT ON BEHALF OF THE FACTORY DEPARTMENT,
AND REFERENCES IN
A.—AGREEMENTS.
In recent years a series of conferences have been
carried out between the Factory Department and
representatives of employers and operatives in certain
trades. In some of these the question of lighting was
raised, and in one instance an agreement was arrived
at. The results of the conferences in this respect may
be summarised as follows:—
- Date of
Industry. Conference. Result.
Cotton weav- || Dec. 1912 | Agreed that passages and
ing. staircases shall be effectively
lighted either by natural or
by artificial means.
Woollen and Oct. 1912 | No decision.
worsted. -
Foundries - || Jan. 1913 | No decision,
B.—CIRCULAR TO OCCUPIERs.
In a circular of the Secretary of State, explaining
the provisions of the Notice of Accidents Act of 1906,
and the Factory and Workshop Act of 1907, and issued
to occupiers on 31.12.07, attention is drawn in the
following words to the importance of adequate
lighting :- ^
- Lighting.—Every workroom should have adequate
windows in the walls or roof, as well as means of
artificial lighting, for the proper illumination of
all parts in which persons are permanently
employed. This is especially important in those
kinds of fine work (more particularly on dark
materials) which involve strain upon the sight.
C.—INVESTIGATIONs.
The following investigations in connection with
lighting have been recorded in the published reports
of the Factory Department:-
Cataract in glass workers.
et seq.)
(A.R., 1907, pp. 250,
(*) A.R. = Annual Report of the Chief Inspector of
Factories.
PUBLISHED REPORTS.
Lighting of bakehouses in London (A.R. 1909,
pp. xiii., xxii.). - -
Illumination in cotton weaving, cotton spinning,
flax spinning, linen weaving, letterpress printing,
clothing factories and handkerchief factories. (A.R.
1911, p. 239 et seq.)
Nystagmus against workers in electric lamp
factories and those employed at sewing machines.
(A.R. 1909, p. 215, 1911, p. 151.)
Artificial lighting of iron foundries.
p. 222 et seq.)
(A.R. 1912,
D.—REFERENCES IN PUBLISHED REPORTs, &c.
The earliest important reference to lighting occurs
in the Annual Report of the Chief Inspector of
Factories for 1909, in which the position of legislation
in this and other countries is summarised.
In the evidence given before the Departmental
Committee on Dangers attendant on Building Opera-
tions (1908) accidents were attributed by some of the
witnesses to insufficient light in the workplaces and
approaches, and suggestions were made that no outside
work should be carried on after nightfall (Questions
2211–28, 4832–43), and that all works and ways should
be sufficiently lighted (Question 2558).
The Report of the Departmental Committee on
accidents in places under the Factory and Workshops
Acts (1911) refers (p. 31) to inadequate lighting as a
cause of accidents. The industries concerned are
included in the Schedule to this Memorandum.
Frequent references to lighting are also to be found
distributed throughout the past reports of the Chief
Inspector of Factories, chiefly in the form of complaints
as to insufficient light in specific industries. These
references are included in the Schedule. -
Mention should also be made of descriptions of
satisfactory methods of lighting in machine sewing
rooms and in a cotton spinning mill. (A.R. 1911,
p. 137.)
APPENDICES. 9
SCHEDULE.
SOME INDUSTRIES IN which LIGHTING IS STATED
TO BE OF SPECIAL IMPORTANCE.
A.—Processes in which High Illumination is required
on account of the Detail of the Work or the Colour
of the Material.
Industry. Special Processes. Reference.
Letterpress printing - || Composing, &c. A.R. 1911,
250–252.
Manufacture Of Machine and A.R. 1911,
clothing, hand- hand sewing. 251–252.
kerchiefs, boots Acc. Rep. p. 31.
and shoes, &c. Min. of Ev.
- q. 17,470.
Weaving of textile Twisting and A.R. 1909, 87.
fabrics. drawing.
Overlooking, A.R. 1907, 157;
- - burling, mending. 1908, 147.
Manufacture of lace - --- A.R. 1907, 157.
B-Factories in which Persons employed are subject to
Risk of Accident on account of Insufficient Light.
Factory. Reference.*
+Docks, &c. - º $º *msea-s
Shipbuilding and yards | Acc. Rep. p. 31; Min. of
dry docks. Ev. q. 14,622. A.R.
1911, 119.
fRailway sidings in &º sº-mºs
factories. - -
Buildings in course of Bg. Min. of Ev. qq. 2211–
construction. 28, 4832–43, 2558.
Iron and steel works -
Acc. Rep. p. 31; Min. of
Ev. q. 12,886.
Factory. Reference.*
Iron foundries tº - || Acc. Rep. p. 31; Min. of
Ev. qq. 13,846, 13,863.
A.R. 1911, 30, 49, 73, 93,
109.
Brass works - tº- - || Acc. Rep. p. 31; Min. of
Ev. q. 14,331. .
Letterpress printing Acc. Rep. p. 31; Min, of
works. Ev. q. 8907.
Hardware factories - Acc. Rep. p. 31; Min. of
- Ev. q. 8907.
f{Electricity generating ****
stations. --
Passages and certain Acc. Rep. p. 31; Min. of
I’OOITAS in textile Blv. qq. 3250, 6342.
factories (preparing
and carding rooms).
C.—Industries in which Insufficient Light tends to caus2
Insanitary Conditions.
flºruit preserving.
fBakehouses (underground).
fWitreous enamelling of metal or glass.
Metal grinding with wet stones.
* A.R.—Annual Report of the Chief Inspector of Factories.
Acc.—Report or Minutes of Evidence of the Departmental
Committee on Accidents in places under the Factory and
Workshop Acts.
Rg.—Report and Minutes of Evidence of the Departmental
Committee on the Dangers attendant on building operations.
(Cd. 3848) (1907).
i. In these industries adequate lighting is already required.
in general terms either statutorily or by Order or Regulations.
AIPPENDIX VII.
REQUIREMENTS AS TO LIGHTING OF FACTORIES, SoHools, AND OTHER BUILDINGS IN FoRCE
IN THE BRITISH EMPIRE.
I.—FACTORIES.
A.—IN THE UNITED KINGDOM.
No general provisions in respect of lighting of
factories and workshops (analogous to those regarding
temperature and ventilation) occur in the Factory Acts.
The only reference to the subject is found in the
Factory Act of 1901, section 101 (4), which specifies
adequate lighting amongst the conditions on which the
Local Authority must be satisfied before an underground
bakehouse is certified as suitable for use.
Under section 79 of the Act of 1901, the Secretary
of State has power to make regulations for certain
trades which have been certified by him to be dangerous.
These regulations, after conforming to a certain
procedure, eventually attain the force of statutory
enactments. Some 20 codes of regulations exist, five
of which contain references to lighting. These may be
summarised as follows:—
, Regulations.
Title. Date.
Requirements.
Docks, &c. - us ~ - || 3rd October
1904.
Regulation 3–All places in which persons employed are employed
at night, and any dangerous parts of the regular road or way
over a dock, wharf, or quay, forming the approach to any such
place from the nearest highway, shall be efficiently lighted.
Provided that the towing-path of a canal or canalised river
shall not be deemed to be “an approach * for the purposes of
this regulation. -
Regulation 7–When the processes of loading, unloading, moving
and handling goods in, on, or at any dock, wharf, or quay, and
the processes of loading or coaling any ship in any dock,
harbour, or canal are being carried on between one hour after
Sunset and one hour before sunrise (a), the places in the hold and
on the decks where work is being carried on, and (b) the means of
* access provided in pursuance of Regulations 4 and 5, shall be
efficiently lighted, due regard being had to the safety of the ship
and cargo, of all persons employed, and of the navigation of
other vessels and to the duly approved byelaws or regulations of
any authority having power by statute to make byelaws or
regulations subject to approval by some other awthority
10 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
Regulations.

Title. Date.
Requirements. .
Use of locomotives, &c., on
premises under the Factory
Act. -
24th August
I906. -
Regulation 7.—Where during the period between one hour after
Sunset and one hour before Sunrise, or in foggy weather, shunting
or any operations likely to cause danger to persons employed are
frequently carried on, efficient lighting shall be provided either
by hand lamps or stationary lights as the case may require at
all points where necessary for the safety of such persons. -
Regulation, 17.—Where persons employed have to pass on foot or
work, no locomotive or wagon shall be moved on a line of rails
during the period between one howr after sunset and one hour
before Swnrise, or in foggy weather, whless the approaching end,
wherever it is safe and reasonably practicable, is distinguished
by a suitable light or accompanied by a man with a lamp.
Provided that this regulation shall not apply to the move-
ment of locomotives or wagons within any area which is efficiently
| lighted by stationary lights.
Witreous enamelling of metal 22nd December
and glass. - 1908.
Generation, &c., of electrical 1st January
energy. 1909.
Manufacture and decoration | 2nd January
of pottery. 1913.
Regulation, 1.-Every room in which any enamelling process is
carried on
this purpose have efficient means of lighting, both natural and
artificial. -
Regulation 26.--All those parts of premises in which apparatus
Žs placed shall be adequately lighted to prevent danger.
Regulation, 15.-All dipping houses and ware-cleaning rooms shall
be well lighted ; neither dipping nor ware-cleaning shall be
done in places which, in ordinary fine weather, are dependent
on borrowed light or artificial light during the hours of
daylight.
shall be efficiently lighted, and shall for
Special Order.—Section 41 of the Factory Act of
1901 extends to Fruit Preserving exemption from the
general provisions of the Act as to period of employ-
ment, &c., subject, however, to certain conditions
prescribed by the Secretary of State by Special Order.
These conditions, dated 11th September 1907, provide,
amongst other things, that :— -
3. In each room in which women or young
persons are employed in pursuance of the special
eacception there shall be adequate
lighting.
Section 9 of the Factory Act of 1901 empowers the
Secretary of State to prescribe a standard of sanitary
accommodation to be observed in all factories and
workshops that are not subject to the Public Health
Acts. A Special Order, made under this Section and
dated 4th February 1903, requires that— -
2. Every sanitary convenience shall be sufficiently.
lighted.
B.—INDIAN EMPIRE.
The Indian Factories Act of 1911, Chap. iii,
contains the following provisions:—
1. Every factory shall be sufficiently lighted.
2. In the case of any factory which is not in the
opinion of the inspector so lighted, the inspector
may serve on the manager of the factory an order
Žn writing, specifying the measures which he
considers necessary for the attainment of a sufficient
standard of lighting, and requiring him to carry
them out before a specified date.
C.—NEW SOUTH WALES.
Under the Factory Act of 1896 (60 Vict, No. 37),
as amended by the Factories and Shops Amendment
Act of 1909 (s. 55), the Governor may make Regula-
tions to require the adequate lighting of any factory
or part thereof. -
The following are now in force:–
Every part of a factory in which persons are
employed, or any passages or portions of a factory
which may at any time be used by an employee,
must have light equal to 10 candle meters, that is,
light equal to that given out by an ordinary stearine
or paraffin candle of six to the lb., at a distance
of I2 inches from the flame. When such lighting
is found by test to be below that standard, the
Inspector may require the occupier to make provision
(preferably, where possible by window openings or
otherwise) to provide the natural or artificial
lighting necessary to bring the lighting wip to the
standard named above. -
II.—SCHOOLS IN UNITED KINGDOM.
The following regulations are in force for secondary
schools:—
The area of window glass should approacimate to
one-fifth of the area of the floor space in rooms used
for teaching, and in other rooms to not less than
one-eighth. -
Every part and corner of a school should be well
lighted. The light in class-rooms must be admitted
from the left side of the scholars. (This rule will be
found greatly to influence the planning.) All other
windows in class-rooms should be regarded as Sup-
plementary or for ventilation. Where left light is
Żmpossible right light is meat best. Windows full
'n the eyes of scholars cannot be approved. Unless
the top of the windows be more than 12 feet above
the floor the plan should show no space more than
20 feet from the window wall in any room used for
teaching. -
(a) Windows should never be provided for the
sake merely of eaſternal effect. All kinds of
glazing which diminish the light and are trouble-
some to keep clean and in repair must be avoided.
A large portion of each window should be made
to open for ventilation and for cleaning.
(b) The sills of the main lighting windows
showld be placed not more than 4 feet above the
floor; the tops of the windows should, as a rule,
reach nearly to the ceiling; the upper portion
should be made to swing. The ordinary rules
respecting hospitals should here be remembered.
Large spaces between the window heads and
ceilings are productive of foul rooms.
(c) Skylights are objectionable." They cannot
be approved in schoolrooms or class-rooms. They
will only be allowed in central halls having ridge
or apea ventilation.
(*) In a letter received from the Board of Education it is
stated :—
“The objection to skylights is not due to any deficiency
in that form of lighting, but to the fact that additional
difficulty is caused in ventilation and heating owing to the
down-draught in cold weather. The Board do not object
to skylights for workshops or for rooms which are not in
wse for sedentary work.”
APPENDICES.
11
(d) The colouring of the walls and ceilings and
of all fittings showld be carefully considered as
affecting the light. This point and the size and
position of the windows are especially important
Žn their bearing on the eyesight of the children.
(e) The windows should be properly distributed
over the walls of the class-rooms so that every desk
shall be sufficiently lighted. The glass line of the
window furthest from the teacher should be on a
line with the back of the last row of desks.()
Similar regulations exist for primary schools.
III.-OTHER BUILDINGS IN UNITED
EINGDOM.
A.—The following instructions upon lighting are
issued by the Local Government Board in respect of
buildings under their control:— -
1. Workhouse Buildings.-Adjacent blocks of
buildings should be placed sufficiently far apart to
allow free access of light and air, and should also
have, where practicable, such an aspect that the
direct rays of the Swn may pass between them during
several howrs of the day (*).
Easternal windows should be filled in with double
hung wooden sashes and should eastend to within
1 foot of the ceiling and to 3 feet or 3 feet 6 inches
from the floor to the ward. The amount of window
surface in a ward showld bear a proportion to the
cubic contents of the ward of about 1 square foot of
window swrface to about every 70 or 80 cubic feet of
space in the ward. The windows should ordinarily
be placed about 8 feet or 10 feet apart from centre
to centre. Windows are not to be glazed with
ground or opaque glass eacept for special reasons to
be approved by the Local Government Board.(*)
2. Poor Law Hospitals.-Eaſternal windows
should be of the double-hung sash type with hopper
hung lights with projecting cheeks over a transom.
The lower sashes may also be hinged to fall inwards
on to supports at each side instead of being double
hung, so that the incoming air is directed upwards.
Windows should eatend to within 18 inches of the
ceiling and to 3 feet to 3 feet 6 inches from the floor
of the ward. The amount of window surface in a
ward should bear a proportion to the cubic contents
of the ward of about 1 square foot of window swiface
to about every 70 or 80 cubic feet of space in the
ward.()
B.—The following reference to lighting occurs in
the Report of the Departmental Committee appointed
to inquire into machinery and engineering staffs at
Poor Law Institutions:—
Para. 23.—Lighting.—The number of institu-
tions where gas is produced on the premises is
small; those where electricity is generated are more
numerous ; but as a rule light is obtained from a
public Supply.
Blectric lighting is generally considered to have
advantages over gas lighting for institutions, but
a saving in cost for illuminating purposes alone
is not usually cownted among those advantages.
Evidence was, however, Submitted to the Committee
of economies effected in cost of lighting by the sub-
stitution of electricity for gas. It was not contended
that light for light electricity was cheaper. The
saving was attributed to the readier facilities for
controlling the use of electricity.
It appears to the Committee, however, that much
more care can be ea:ercised in controlling the con-
Swmption of gas than is at present often the case, and
that sufficient advantage has mot been taken of the
opportunities of economising by the use of incan-
descent mantles. On the whole, it does not seem to
() Building Regulations for Secondary Schools, Part II.,
Rule 6.
(*) Memorandum as to points to be attended to in the
Construction of Workhouse Buildings, par. 6.
(3) Par. 90. -
(*) Memorandund on the Construction of Poor Law Hospitals,
par. 30.
them that there is adequate evidence to justify the
substitution of electricity for gas at institutions
where gas is already in use. At new institutions
the question is more open and depends largely on
local conditions. -
Where electricity is installed consideration should
be given to the use of metallic filament lamps, which
consume much less current in proportion to the light
given than carbon filament lamps.
C.—STATUTORY REQUIREMENTs.
1. The following may apply to new streets and
buildings.
JEvery person who shall erect a new building
shall construct in every habitable room one window,
at the least, opening directly into the easternal air,
and he shall cause the total area of such window, or,
if there be more than one, of the several windows,
clear of the sash-frames, to be equal at the least to
one-tenth of the floor area of such a room.
Such person shall also construct every such
window so that one-half, at the least, may be opened,
and so that the opening may eaſtend in every case to
the top of the window.()
N.B.-These byelaws have no statutory force apart
from their adoption by local authorities and subsequent
confirmation by the Board. They are, however,
generally adopted by such authorities as the basis of
byelaws made by them under the statutory provisions
in that behalf. Although local authorities are not
empowered by the Public Health Acts to make bye-
laws for securing the lighting of buildings, the clauses
under the statutory sub-heading—
“With respect to the sufficiency of the space about
buildings to secure a free circulation of air, and
with respect to the ventilation of buildings ’’
(of which Clause 56, quoted above, is one) have no
doubt in practice an effect upon this matter.
2. Local authorities are empowered by section 17
of the Housing, Town Planning, &c. Act, 1909, to
make regulations, with the Board's consent, in the
special case of underground rooms habitually used as
sleeping places for securing, amongst other things,
the proper lighting of such rooms.
A draft of such regulations, which is under con-
sideration by a number of local authorities, contains
the following reference to lighting:—
Clause 8.—(i) The room shall be effectually
lighted by means of one or more windows opening
directly into the eaſtermal air.
(ii) Every such window shall be so constructed :
that one-half at the least may be opened and that
the opening may eastend to the top of the window.
__ (iii) The total area of such window or windows
ſ' clear of the sash frames shall be equal at the least
to one-eighth of the floor area of the room and a
portion of such total area equal in eastent to at
least one-tenth of such floor area shall be 80 situated
that a line making an angle of 30 degrees with a
horizontal plane can be drawn upwards from any
point thereon in a vertical plane at right angles to
the plane of the window so as not to intersect within
a distance of 10 feet measured horizontally from the
window any wall of any area adjoining the room or
any other wall or any kerb or other obstruction
ea:cept an open fence.
º, For the purpose of this paragraph a bay window
having side lights shall be assumed to be equivalent
to a flat window of the same area and of the same
height in relation to the room and situated at a
distance from the outside area wall equal to the
mean width of the area.
(iv) In estimating the area of a window or
windows for the purpose of this regulation no
account shall be taken of any part of any such window
which is above the mean level of the ceiling of the
7°OO%).
(v) Any such window or windows shall overlook
the area or open space provided in pursuance of the
regulation in that behalf.
() Model Byelaws, Clause 56.
a 30030
12
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
-**
APPENDIX VIII.
REQUIREMENTs as to LIGHTING of FACTORIES and ScHools in force in certain FoEEIGN
CountRIES on 30th September 1913.
I.—FACTORIES.
A.—AUSTRIAN EMPIRE.
In Austria the following requirement applies to all
factories and workshops:–
During the period of employment it is the duty
of the occupier to take care that the workrooms
are kept as light, as clean, and as free from dust
as possible so far as the nature of the work .
admits.()
The new Factory Act, which came into force in
August last, re-enacts the above requirement with the
addition :-
and to provide the workrooms and shops, if
necessary, with adequate artificial light.(?)
In Hungary no legal requirements exist, but the
instructions to inspectors of factories contain the
following paragraph :-
As regards the lighting of rooms in factories,
attention must be paid to the light coming from
the windows as well as that derived from lamps,
and allowance must be made for the nature of the
work carried on. When the work is trying to the
eyesight a stronger light must be provided ;
when the work is less trying, a weaker light is
sufficient.(?)
B.—BELGIUM.
The following provisions apply to all industrial
and commercial undertakings subject to the Act of
December 24th, 1903:-
All workrooms shall be efficiently lighted.
During daytime they shall be furnished with
adequate natural light ; provided that artificial
light is permissible if, owing to the situation of
neighbouring buildings or to the eaſigencies of the
processes carried on, natural light sufficient for
the work cannot be obtained.(*)
Constant and adequate artificial illumination
shall be provided. Adequate means shall be taken
to prevent the overheating of the rooms and the
vitiation of the air.(?)
Persons employed shall be protected against
eaccessive radiation from the means of lighting,
ovens, furnaces, and other sources of heat.(?)
The lighting shall be sufficient to enable the
machinery, transmission gear, and other appliances
Žnvolving danger, to be readily distinguished. All
places where work is carried on or over which
persons are liable to pass shall be illuminated
sufficiently to enable all dangerous places to be
easily distinguished.(?)
The use of petroleum and of all other mineral
oils and spirits is forbidden for portable lamps
known as “crassets” and for all other dangerous
appliances.(*)
The use under any preteat of fire or of lamps
other than safety lamps is forbidden in places
where, in spite of all precautions, eaſplosive or
ºnflammable gases, vapours, or dust are liable to
occur.(*) -
Persons employed are forbidden . . . . to
make use under any preteat of lamps, eacept
safety lamps, in parts and places where, in spite
of precautions, inflammable or ea plosive gases,
vapours, or dust are liable to occur.(*)
The following are special requirements applicable
to the work of loading, unloading, repairing or
maintaining of ships and boats, as well as to the
(*) Regulations as to Trade and Commerce, par. 74.
(*) Factory Act of April 21st, 1913 (Off. Gaz., No. 74).
(*) Instruction of March 30th, 1901, par. 25, C.
(*) Royal Decree of March 30th, 1905, Art. 6.
(*) Ibid., Art. 7. (*) Ibid., Art. 9. (?) Ibid., Art. 42.
(*) Ibid., Art. 43. (*) Ibid., Art. 44. -
(*) Ibid., Art. 52. -
handling of merchandise, so far as these processes
are carried on in docks, dry docks, graving docks,
wharves and quays:–
All places where any work is carried on, or over
which persons are liable to pass, shall be illumi-
mated sufficiently to enable machinery, transmis-
sºon gear, and other sources of danger to be
distinguished.() - .”
The lighting of the plant and appliances used in
the places specified in the preceding article shall be
so installed, arranged, and maintained as to afford
all possible security to the persons employed.
When the lighting is derived from petroleum or
other mineral oil or spirit, means shall be taken to
prevent the falling, upsetting, or ea:plosion of the
lamps and of leakage of the liquid ; in particular,
the lamps shall be constructed sufficiently solidly,
their reservoirs shall be closed by screw stoppers,
and the tubes for the passage of the wicks shall be
furnished with an arrangement for preventing
leakage of the liquid.(*) - . . .
The use whder any preteat of fire or lamps other
than safety lamps is forbidden in places where, in
spite of precautions, inflammable gases, vapours, or
dust are liable to occur.(?) -
The following requirements apply to places used
temporarily as lodgings for persons employed on
brickfields and in stone-yards:– ' '
The premises shall be adequately lighted by
windows in sufficient mumbers and of an area equal
to at least one-tenth of the area of the floor of the
room. Broken panes shall be immediately re-
placed.(*) - . . .
The lighting plant and appliances shall be so
arranged and maintained as to afford all security
against fire.(?)
C.—DENMARK.
The following general requirement applies to all
factories —
The lighting of workrooms shall be adequate as
regards both the carrying on of the work and the
visibility of the machinery and other objects
present in the rooms. When artificial light is used,
the sources shall be switably placed.(")
In the draft of the new Factory Bill the above has
been amended as follows:–
The lighting of workrooms shall be adequate as
regards the carrying on of the work. When
artificial light is used, it shall be suitably placed.()
In addition to these statutory provisions, references
to lighting occur in a few of the codes of regulations
applicable to special trades:— -
There shall be ample room for the admission of
daylight and air.(?) - - . . .
Workrooms shall be provided with windows which
are sufficient in number and size to give adequate
light to all workplaces.(*)
Other codes contain the requirement that where
artificial light is in use, there shall be adequate
provision against the pollution of the air.
It may be added that the Directorate to whom
plans for new buildings, especially bakehouses, are
submitted have expressed the opinion that unless
(1) Royal Decree of November 20th, 1906, Art. 31.
(*) Ibid., Art. 32, as amended by Royal Decree of Sep-
tember 7th, 1910. -
(3) Royal Decree of November 20th, 1906, Art. 33.
(*) Royal Decree of June 15th, 1910, Art. 6.
(*) Ibid., Art. 13. -
(*) Machinery Protection Act of April 12th, 1889, and
Factory Act of April 11th, 1901, Art. 6.
(7) Factory Act of , Arts. 8 and 14.
(*) Letterpress Printing Regulations of January 9th, 1904.
(*) Cigar-making Regulations of June 1st, 1904. .
APPENDICES.
13
special conditions prevail, a window area of 15 per
cent, of the floor area may be considered satisfactory.
D.—FRANCE.
The following requirements apply to factories,
manufactories, workshops, workplaces, yards, shops, and
offices of all kinds:– .
All indoor premises used for the carrying on of
work, their anneapes, and especially the passages and
stairways, shall be adequately lighted.()
The use for lighting or heating purposes of any
liquid emitting inflammable vapours below 35 Cent.
Žs forbidden, unless the appliance containing the
liquid is firmly fia!ed during working howrs; the
part of the appliance containing the liquid must be
closed so as to prevent leakage of the liquid.
When persons employed are present, filling of the
lighting or heating plant with combustible liquid,
both ºn the workrooms and in the passages and
stairways, shall only be carried out in daylight
and on the condition that no source of fire is
present. -
The pipes conveying gas to the lighting and
heating appliances shall be constructed of metal or
covered with metal. - .
The flames of portable lighting and heating plant
must be distant at least one metre vertically and
30 centimetres laterally from all inflammable parts
of the building, plant or material; provided that
shorter distances are allowed in case of necessity
so far as regards the walls and ceilings, if an
Žncombustible screen not in contact with the wall
Žs interposed. -
Portable lighting appliances must have a stable
and solid base. -
Every fiased and portable lighting appliance,
whenever necessity arises, must be furnished with
a glass chimney, a globe, wire netting or some other
suitable arrangement for preventing the flame from
coming into contact with inflammable material.(*)
E.-GERMAN EMPIRE.
The following are imperial requirements applicable
to all factories and workshops —
The occupier is required to arrange and maintain
the workrooms, plant, machinery and appliances)
and to regulate the carrying on of the work in such
a 'way as to protect the persons employed against
danger to life or health, so far as the nature of the
work admits. In particular, care must be taken to
provide adequate lighting. . . . . . . .(?)
In addition, the following provisions apply to
certain specified trades:– . . . . .
In rooms in which persons are employed in type-
setting, or the preparation of type or stereotype
plates, the following provisions apply –
1. The floor of the room must be not more than
half a metre below the surrounding ground level.
Eaceptions may be allowed by the higher adminis-
trations, if healthy conditions are attained by
efficient insulation of the floor and admission of
sufficient light and air. e & -
3. . . . . The rooms must be furnished
with windows, sufficient in size and numbers to
admit adequate light to all the workplaces. The
windows must be capable of being opened for
purposes of ventilation.(*) .
Rooms in which stripping of tobacco or
wrapping, rolling or sorting of cigars is carried
on must conform to the following requirements
... ' They must be provided with windows
leading directly to the open air and sufficient in
size and numbers to admit adequate light to all
the workplaces. The widóws must be so con-
gtructed that they are capable of being opened to
the eaſtent of at least one half of their surface.(?)
(‘) Decree of November 29th, 1004, Art. 5, par. v.
(*) Ibid., Art. 17, par. a.
(*) Gewerbeordnung für das Deutsche Reich, S. 120a.
(*) Imperial Decree of July 31st, 1897 (R.G.B., p. 614), S. 1.
(*) Proclamation of Imperial Office of February 17th, 1907
(R.G.B. p. 34), s. 3. -
The following requirement applies to workplaces in
which a person employs only members of his family, or
in which one or more persons carry on industrial work
without being employed by the occupier carrying on
the business of the workplace —
If it appears that in any process the nature of the
work is such that danger to life, health or safety
'may result, the proper police officer, on application
by an inspector, may, by order, prescribe such
measures as are necessary for the carrying out of
the following requirements :– - . &
The workrooms, including the plant, machinery
and appliances, must be so constructed and main-
tained that the house worker is protected against
danger to life or health, so far as the nature of
the work admits. In particular, care must be
taken to ensure that there is adequate lighting
.()
In Prussia certain trades are subject to special
requirements. Thus, the “Principles for the indus-
“ trial police supervision of works in which the
“ manufacture of celluloid goods is carried on and of
“ warehouses connected with them,” include the
following:— : - -
In newly erected buildings, only electric glow
lamps, furnished with strong protecting globes, shall
be used for the lighting of workrooms, and the main
switch shall be placed outside the room. In easisting
works incandescent gas is allowed where electric
light is not available, if it is placed at least one metre
from the place of work, is firmly and securely fia!ed,
and is provided with a plate to guard against flying
shavings, falling fragments of glass, &c., and with
a smoke cap. Open gas and oil flames are for-
bidden.(?)
The following requirement applies to celluloid
warehouses for raw materials, finished goods and
waste — - - - . .
The light shall be derived either from daylight,
from fireproof enclosed outside lights, or from
electric glow lamps with protecting globes.(*)
The draft of a police order relating to the manufac-
ture of carbonic acid beverages and the trade in such
beverages contains the following:—
Rooms in which the beverages are prepared must
be brightly and well lighted and must be kept clean.
The apparatus must be so placed that it can be
dinspected on all sides.(*) .
F.—HOLLAND.
The Safety Law of 1895 enacts that regulations may
be made regarding matters relating to the safety and
health of persons employed in factories and work-
shops.() The regulations made in pursuance of this
contain the following provisions regarding lighting —
1. So far as practicable, all workrooms must be
adequately lighted during the period of employ-
ment. x -
9. In workrooms provision must be made for
excluding direct sunlight from places where work is
being carried on. . . . . . . .
3. In places where the following processes are
carried on : . . . . . . - -
(a) Embroidery,
(b) Working in diamonds and other precious
stones,
(c) Working in gold and silver,
(d) Engraving on wood,
(e) Manufacture of scientific instruments,
(f) Composing, * - - - -
(g) Mechanical knitting,
(h) Sewing,
(i) Draughtmarship,
(1) House Work Act of December 20th, 1911 (R.G.B.
p.976), s. 6. - - tº º f : &
(*) Order made in pursuance of the Ministerial Decree cf
May 7th, 1910, A. II. 3.
(*) Ibid., A.I. 10. ... -- . . . .
Ö Order made in pursuance of the Ministerial Decree of
August 26th, 1911. - ** .
(*) Safety Law of July 20th, 1895 (Statute No. 137), Art. 6.
C 2
DEPARTMENTAI, committee on LIGHTING IN FACTORIES AND WORKSHOPS:
(k) Needlework,
(1) Making and repairing of clocks and watches,
the illumination must amount to an intensity of at
least 15 normal candles at a distance of one metre,(')
and for places where other processes requiring a
good light are carried on, the illumination must
amount to an intensity of at least 10 normal candles
at a distance of one metre.(*)(*)
The recent Labour Law of 1911 allows regulations
A young person or a woman shall not be employed
on work—
J. involving ea:posure to intense radiant heat,
glaring light, or splashing or droppings from a
dangerous liquid, whless efficient means of protection
are provided and kept available for use by the
gowng person or woman, ;
K. or which, in the opinion of the inspector for
the district, in consultation with the medical adviser,
eaposes the young person or woman to risk of severe
injury to the eye or to deterioration of the eyesight,
wnless a declaration is made by an oculist appointed
by the district inspector in consultation with the
to be made prescribing the conditions of work for yourg
persons and women in factories and workshops.(*) The
regulations made in pursuance of this contain the
following important requirements as to lighting :—
A young person or a woman may not be employed
Žn a factory and workshop—
A. in any workroom which is not adequately
lighted during the period of employment ;
B. at any place of work which cannot be protected
from the direct rays of the sum, if the district
Žnspector of factories is of opinion that the conditions
would be injurious to the young person or woman ;
and -
C. in workrooms in which during the time between
9 o'clock in the morning and 3 o'clock in the after-
moon artificial light must be used in order to obtain
adequate illumination, eacept in so far as exceptional
meteorological conditions make the wse of artificial
light necessary.
The provisions made under A. and C. are not
applicable to the employment of a young person or
a woman in a workroom in which, owing to the
nature of the processes carried on, daylight cannot
be admitted or full daylight illumination cannot be
maintained, as required under A., provided that—
(a) no work must be carried on by the young
person or the woman in Swch a room at any other
times than those specified by the occupier in a
written motice of the hours of employment;
(b) the hours of employment shall be so arranged
that the young person or woman shall on every
day have an opportmnity of spending in the
daylight the number of hours considered necessary
for health ; and
(c) the notice of hours of employment required
wnder (a) shall be affia!ed in a conspicuous place
Żm the workroom after it has been forwarded to
the inspector for the district and has been furnished
with his written approval.
If the inspector for the district refuses his approval
as required, the occupier may appeal to the Minister,
who shall cause inquiry to be made.
If it then appears to him that the hours of em-
ployment should be approved, he shall give notice to
that effect to the inspector and to the occupier, and
the inspector shall then give his approval to the
motice of hours of employment.
If it appears to him that the scheme of work
should not be approved, he shall motify the inspector
and the occupier of the modifications which are
necessary in order that approval may be given. In
applying the conditions under (c) the inspector shall
then conform to the opinion of the Minister.
In regard to the provisions under A., no workroom
shall be considered adequately lighted in which the
area of the light openings is less than one-tenth of
the floor space, whless, on account of eaceptional
circumstances, the inspector for the district considers
the lighting adequate.
A written approval, as required under (c), may
be withdrawn at any time by the inspector for the
district, if it appears to him that the approval of
the scheme is wr.justified. -
Approval given by authority of the Minister
cannot be withdrawn eacept by the awthority of the
Minister.(")
medical adviser with regard to the young person or
woman, certifying that the process involves no special
danger to the eyesight and specifying the precise
means of protection or assistance to be kept available
for use by the young person or woman.
The prohibition under J relating to the ea:ecution
of work involving eaſposure to intense heat or glaring
light, shall not apply to processes of such a nature
that eaſposure occurs occasionally and for a short
period only, or the use of suitable means of pro-
tection involves special difficulties, whless the inspec-
tor for the district has notified the occupier of the
factory or workshop that in his opinion the work
carried on under the specified conditions is in-
jurious for the young person or woman. -
The declaration required winder K must be in a
form prescribed by the Minister.()
A young person or a woman shall not be employed
Žn a factory or workshop on–
A. (1) Embroidery,
(2) Weaving of damask, silk, or coloured cotton
goods,
(3) Working in diamonds, or other precious
Stones,
(4) Grinding of glass,
(5) Wood engraving,
(6) Making of Scientific instruments,
(7) Manufacture of lace,
(8) Stringing of beads,
(9) Composing,
(10) Mechanical knitting,
(11) Making of gold and silver articles,
(12) Manufacture of articles of hair,
(13) Sewing,
(14) Stitching, eacept stitching of leather,
(15) Draughtsmanship,
(16) Making and repairing of clocks and
watches,
wnless the illumination on the place of work
amounts to at least 30 Hefner wmits at a distance
of one metre (*); or - -
B. Any kind of work not included under A. which
Tequires good light, unless the illumination on the
place of work amounts to at least 20 Hefner units at
a distance of one metre.(3)(*)
In addition to these general requirements, special
provision as regards lighting have been made for
certain industries.
Thus, the Caisson Act of 1905 enacts as follows:–
For the protection of persons employed in or
about the construction of building work winder
greater than atmospheric pressure, eertain provi-
º have been established by regulation in respect
OT : —
*-
(d) the lighting of the premises, and erections in
which persons must remain under greater than
atmospheric pressure, such as work chambers, shafts,
locks, and compression sluices.(?)
These regulations provide as follows:–
The premises must be lighted sufficiently to enable
the persons employed to find their way about in
Safety.(*)
- () Royal Decree of December 6th, 1911 (Statute No. 352),
(*) Equivalent to approximately 1 5 foot-candles. Art. 9. * -
2 & (*) Equivalent to about 3 foot-candles.
3 2
(*) Royal Decree of December 1896 'statute No. 215), ( * } }} 53
Art, 60. (*) Ibid., Art. 19. - -
(*) Labour Law of October 20th, 1911 (Statute No. 319), (*) Caisson Act of May 22nd, 1905 (Statute No. 148),
Art. 5. Art. 1.
(*) Royal Decree of December 6th, 1911 (Statute No. 352), (*) Royal Decree of January 26th, 1907 (Statute No. 20), -
Art. 16. Art. 27.
APPENDICEs. 15
The chambers, shafts, and lock sluices must be
adequately lighted. For artificial lighting only
electric light shall be used.()
Whilst work is being carried on in the chamber
the foreman must be continuously provided with
an efficient electric hand lamp for wse in emer-
gencies.(*)
Finally, the Stonemasons’ Act of 1911 provides
that—
In accordance with the further instructions fur-
mished to him by the inspector for the district, the
contractor shall see that all places where stone-
masonry is carried on whder his control shall comply
with the requirements contained in the general
regulations in regard to lighting.(*)
These regulations provide as follows:—
Every workroom and shed shall be adequately
lighted in all parts where work is being carried on.
In every case the following provisions shall
apply :—
(a) The total area of the light openings of a
workroom which admit light when the doors are
closed shall amount to not less than one-sia,th of the
floor area ;
(b) The distance from the place where any stone-
mason works to the nearest light opening shall not
eacceed sia, metres, whless Sufficient daylight is
admitted to the place of work from the ceiling or
roof.()
G.—ITALY.
The only reference to lighting in the Italian code
occurs in the Royal Decree for the prevention of
accidents in factories and other industrial establish-
ments:— -
The lighting of these buildings must be of such a
nature as to allow the machinery and means of
transmission to be clearly distinguished by the
persons employed.(?)
FI.-NORWAY.
The only reference to lighting is contained in the
following general requirement —
All workrooms shall be adequately lighted by
imatural or artificial means, in Such a way that all
moving parts of machinery involving, when in
motion, danger to persons employed may be clearly
distinguished.
In all workrooms in which ea plosive or readily
Žnflammable gases, fumes, or dust are or may be
generated artificial lighting shall be produced by
appropriate means.(") ...
FC.—SWEDEN.
The only legal requirements occur in a recent Act
for the protection of labour, which enacts as follows:–
For the prevention of accidents arising from work
the employer shall observe the following regulations
Žn particular :—
(o) Satisfactory illumination shall be provided.6)
For the prevention of illness arising from any
process the employer shall observe the following
requirements in particular :—
(b) The work shall be carried O??, in a suitable and
sufficient light. . . . .(*)
More precise instructions are contained in two
circulars distributed from the Swedish Factory Depart-
ment :—
Adequate lighting must be provided not only for
workrooms and workplaces, but also for stairways,
passages, and transmission gear rooms.()
(1) Royal Decree of January 26, 1907 (Statute No. 20),
Art. 28. -
(*) Ibid., Art. 29.
(*) Stonemasons'
No. 315), Art. 6.
() Royal Decree of January 20th, 1913 (Statute No. 38),
Art. 6.
(*) Royal Decree of June 18th, 1899 (No. 230), Art. 1.
(5) Factory Act of September 10th, 1909, Art. 11.
(*) Labour Act of June 26th, 1912 (No. 206), Art. 4.
(*) Ibid., Art. 5.
(*) Factory Inspection Circular of December 4th, 1902
(No. 4), Par. 2.
a 30030
Act of October 7th, 1911 (Statute
Workrooms should be provided with good natural
lighting.
Artificial light should be convenient and adequate.
During working hours all moving parts of the
machinery and all obstructions on the floor which
might be productive of danger, hoist and stair
openings, breaks in the floor and similar openings,
should be well lighted.
Stairways, passages, and gards showld always be
adequately lighted.()
L.—UNITED STATES OF AMERICA.
In the majority of States the question of lighting
has received little attention and specific regulations on
the subject are rare. There is, however, in most
States a Factory Inspection Law, under which in-
spectors are required to satisfy themselves, amongst
other things, that the lighting arrangements are ade-
quate for the wellbeing of the persons employed, and
they are empowered to order any alterations they may
deem necessary.(*) In some States plans of new
factory buildings Urust be submitted to and approved
by a Board appointed by the State authorities.(*) In
other States there is no legislation on the subject.(?)
A few points of special interest may be mentioned.
In Connecticut an inspector must be satisfied that
workrooms are properly lighted and may order the
removal of grained, painted, or corrugated glass where
it is injurious to the eyes of the workmen.
In Maryland, in addition to the general require-
ment of adequate lighting, the following provision
exists :—
Amy room or apartment e wherein if
of less superficial area than 500 square feet, any
artificial light shall be habitually used between the
hours of 8 a.m. and 4 p.m. . . shall be
deemed to be a place involving danger to the public
health. . . . .(?) -
In the City of Portland, Oregon, the Building Code
lays down in great detail definite requirements for the
proportion of window space to floor area for various
classes of buildings, including factories:–
All buildings shall be so placed upon building
sites as to secure proper natural light and ventilation
for the occupants thereof, and for the purpose of this
Title, no building, the interior of which is left in
one space as a whole, or is divided or partitioned off
into rooms or spaces of limited area, with Or without
enclosed passageways or other intervening rooms or
spaces between, shall be deemed in a proper Sanitary
condition whless each room or space shall have one
or more properly proportioned, adjustable glazed
doors or windows, or both, or ventilated skylights
opening directly into an open air space of a street,
gard, lawn or court.(")
The window areas for properly lighted rooms shall
never be less than the following given as a fraction
of the floor area to be lighted; the smaller fraction
Žs for rooms lighted from unobstructed continuous
air spaces or streets 30 feet or more in width, and
the larger for eaterior air spaces of less width than
30, but the minimum width of courts shall not be
(l) Factory Inspection Circular of December 16th, 1909
(No. 18), Par. 11. -
(*) The following States have Factory Acts in which
adequate lighting is required in general terms:—New York,
Connecticut, Rhode Island, Massachusetts, Vermont, Maine,
Pennsylvania, Ohio, Colorado, Illinois, Michigan, Nebraska,
Maryland, Kansas, Missourie, South Carolina.
(*) Plans must be submitted for approval in the following
States:—Wermont, Maine, and Oregon. -
(*) No legislation appears to exist in the following
States : —New Hampshire, Texas, New Mexico, Delaware,
Georgia, Washington, Idaho, Montana, Mississippi, Alabama,
Florida, North Dakota, Indiana, Minnesota, Wyoming, Vir-
ginia, West Virgina, Arkansas, Kentucky, Tennessee, Nevada,
Utah, Arizona, the territory of Alaska, and the city of East
St. Louis.
(5) Public General Laws of Maryland, 1904, Art. 27,
Section 247.
() Buildings Act, City of Portland, Oregon, Art. 510.
C 3
16
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
less than 6 feet; provided, however, that interior Gr
line courts may be one-half of the above width for
one building, but if windows of two buildings open
in such court, the court shall be the full width.
For Buildings(*)—
Grade I. - Division a and b - 1/8 and 1/6
Division c - - 1/6 and 1/4
Grade II. - Division a - - 1/9 and 1/7
- Division, b - - 1/8 and 1/6
Division c - - 1/10 and 1/20
Division d - - 1/20 and 1/20
Division e and f - 1/6 and 1/4
Grades III. and IV. º - 1/10 and 1/8
Buildings when erected for use as stores, workshops
and factories (warehouses eacepted) located on streets
and courts and lighted as prescribed in Section 511,
the interior space of which remains unobstructed
eacept by columns and the necessary elevators and
stairs ‘so placed as not to interfere with the proper
transmission of light and air, will be deemed
sufficiently lighted and ventilated, subject to other
prescribed conditions of their special occupany, when
their depths or proportions do not exceed the following
number of times the window-head height above the
OO)" : — - -
fl (a) For through buildings from street to street or
from a street to an unobstructed space of equal
width of a street, ten ; if one end has a court, alley
or yard of less width than a street, eight.
(b) For corner buildings facing two streets, or a
street and an open space at least as wide as a street,
sia, from each street.
() Factories are covered by Grade II, Division e. and
workshops by Grade II., Division f.
schools in Lower Austria :—
For corner buildings facing a street and a court-
yard, courtway or alley of less width than a street,
sia, deep from the street and four deep from the
other dimension. •. -
(c) For corner buildings facing three streets,
fourteen in the longest and eight in the shortest
dimension. - \ -
If one or two of the sides faces an alley or open
space less than the width of a street, the shortest
dimension, shall not eaceed sia, and ºf the principal
source of light is from two parallel streets with an
alley along the other side, the shortest dimension
shall not eaceed four. -
(d) If a building faces four streets, the dºmensions
shall not eaceed sæteen in each direction ; if lighted
by two opposite streets and situated between alleys,
courts or yards of less dimension than a street, the
dimension from street to street shall not ea:ceed
sia:teen and the other dimension twelve ; if the
building faces two intersecting streets and two
Žntersecting alleys or spaces narrower than a
street, the dimension shall not eaceed twelve in either
direction.(?) -
In the State of California the following provision is
in force :—
No basement, cellar, underground apartment, or
other place which the Commissioner of the Bureau
of Labour Statistics shall condemn as unhealthy
shall be used as a workshop, factory, or place of
business in which any person or persons shall be
employed.(*)
(*) Buildings Act, City of Portland, Oregon, Art. 511.
(*) Act of February 6th 1889, section 3. -
II.-SCHOOLS,
A.—AUSTRIAN EMPIRE.
The following provisions apply to all national
The lintel of the window must be as near as
possible to the ceiling. -
The distance between the lintel of the inside
window recess and the ceiling mºst £n no case
eacceed 15 centimetres (6 &nches).
This condition can be easily fulfilled by the w8e
of a cross-piece in the construction of the lintel of
the window recess or by the formation of the ceiling
out of beams inserted between the cross-pieces.
The light must reach the pupils from the left
side. Windows must not be provided in both the
principal walls. - -
The total area of the window openings of a
classroom must amount to at least one-sºath of the
floor space, if completely unobstructed, and to one-
fourth, if the light is obstructed by neighbouring
buildings. - -
The height of the window Sill must be not less
than 1 : 1 metres (3 feet 7 inches) and not more than
1 : 5 metres (4 feet 11 inches). . . . .
The piers of the window wall, which adjoin
the principal walls of the classroom, must not
eacceed 0-75 to 0.9 metre (2 feet 6 inches to 3 feet)
'n width measured up to the window frame, and the
piers between the windows must be made as narrow
as the method of construction (steel, stone or bricks)
admits. If bricks are used, the width of the pier
must not exceed the limit of two brick lengths over
and above the depth of the window case, whless in
the case of buildings with several storeys further
strengthening can be shown by calculation to be
mecessary, having regard to the load on the piers.
In such instances it is advantageous to increase the
thickness of the walls rather than the width of the
piers. The windows of a room should, as a rule, be
of the same width throughout, and should be not
less than 1 : 5 (4 feet 11 inches) metres in width.
If deviation from these conditions is applied for,
Žt must be shown that the illwmination of the school
desks will not be detrimentally affected thereby.
Classrooms mºst have dowble windows; wooden
casings to the window recesses should not be
supplied, but the window cases (80 far as the
construction of the piers admits) and also the lintels
should be bevelled, and the bevelled parts plastered
and painted white.
The inside of the windows should be painted in a
light colour.
The windows must be so constructed that they
can at all times be completely opened to secure
ventilation. -
Switable arrangements must be made for keeping
the windows open.
The window panes must be clear and quite trans-
parent.
The sashes and cross-bars of the windows
should be so arranged that they obstruct as little
as possible. This is especially important in the
divisions of the upper section of the window, which
7s the more effective for the lighting of the room.
Division of the window into three parts is
permissible. -
It is recommended that where" practicable the
window frames should be constructed of iron.()
During instruction no direct sunlight nor Swnlight
reflected from opposite buildings must be allowed
to enter the room.
As a protection against such light, only those
curtains should be used which completely cover the
window and are fiaſed inside the window recesses.
The curtains should be made of light, wºbleached
material without pattern. The curtains can be
arranged 80 as to be drawn from above (window
blinds) or may consist of two overlapping portions,
to be drawn from the side.(?)
For the general artificial lighting of class-
rooms the use of diffused lighting reflected from the
ceiling is recommended as the best, a system which
can be easily adapted to electric light and
'ncamdescent gas. For lighting by means of
pendants, electric light, incandescent gas or mineral
oil may be used according to the local conditions.
(*) Order of the Lower Austrian School Board, dated
23rd November 1905, §10, -
(*) Ibid., § 11,
APPENDICES. - - - - - - - - 17
In both the last cases the lamps must be
provided with globes, and all hanging lamps must
be provided with appliances screening the lights from
the eyes. - : .
When the indirect method of lighting is used,
the ceiling should be painted with some light-
coloured, easily cleaned material. For illumina-
tion by means of pendant lamps, these should be
provided with Switable shades of obscured or white
glass (opal) in order to increase their efficiency.
. The sources of light must be fia:ed at least
0. 5 metre (20 inches) away from the heads of the
pupils when reading or writing.
Care must be taken that the lamps are so
distributed as to ensure that the illumination over
the working plane is as uniform as possible.
Blackboards, maps, &c., must be particularly
well illuminated, care being taken that the sources
of light are screened from the direct vision of the
pupils by the provision of Switable shades.
The illumination shall be sufficient to enable
diamond type to be easily read by a normal /eye at
a distance of half a metre (20 inches), corresponding
to a minimum illumination of 10 normal metre-
candles (about 1 foot-candle).
Especial care must be devoted to the cleaning and
ºfficient upkeep of the light sources.()
B. —BELGIUM. ^,
The lighting of classrooms in the primary schools
is regulated by the official requirements of 27th No-
vember 1874. Certain modifications, due to the
advance in educational hygiene, have been introduced
in some of its provisions and form the subject of the
Instructions of 14th March 1892.
The following requirements were originally in
force :—
The windows shall be lateral, and shall face, as
far as possible, the directions south-east and north-
west.
If it is impracticable to arrange the windows on
two sides they must be placed on the left of the
pupils and situated, ºf possible, in the wall opposite
the platform.
The number representing the glass area of the
windows shall be not less than one-twentieth of the
number representing the cubic capacity of the room.
The lower panes may be constructed of roughemed
lass.
9 The upper part of the window frame shall be so
constructed as to allow this to be opened at will.
The sides and bottom of the window bays shall be
splayed. t
The windows shall be furnished with blinds
capable of being raised from below instead of being
lowered from above.(*) - -
It is now recommemaled that classrooms should
have dimensions of 7 metres by 8 or 9 (23 feet by
26 to 30 feet) with unilateral lighting, which is
Tecognised as being the best system in that it avoids
the crossing of light and allows the desks to be
arranged so that the pupils receive the daylight from
the left.
But provision must be made for the light to reach
the furthest parts of the room and to be distributed
as viniformly as possible. With this object it is
necessary that the following conditions should be
observed :-
The windows are to be situated in one of the
great sides of the rectangle, and the width of wall
between any two bays is to be reduced to a
maaſimºwm of 50 to 80 centimetres (1 foot 8 inches
to 2 feet 8 inches); the tops of the windows should
be horizontal and show.ld reach as near as possible
to the ceiling, i.e., within 25 to 30 centimetres
(10 inches to 1 foot), the Sills being about 1 to
1.20 metres (3 feet 3 inches to 4 feet) from the
OO!". -
fl The height of 4: 50 metres (14 feet 9 inches)
remains in force for classroom, and the ceiling
must be horizontal. -
(*) Ibid, § 12.
(*) Ministerial decree of 27th November 1874,
In the conditions prescribed above for the
windows it is useless to observe the requirement as
to the ratio between window area and cubic space in
schoolrooms since this ratio has no rational basis.
School premises with unilateral lighting should
receive the daylight from the west or better from the
east. In the case of bilateral lighting it is recom-
mended that the windows show.ld face east and
west.(?)
In schools where artificial light is used (evening
adult classes, &c.), care must be taken that
moa;ious products of combustion are removed by
placing above the light sources pipes connected with
the central flue and arranged so as to eaſpedite the
ventilation. A distance of about 1:40 metres
(4% feet) should be maintained between the desks
and the reflectors in order to protect the heads
of the scholars from eaccessive heat.(?)
No legal provisions are in force with regard to the
lighting of lower secondary schools, which is under the
control of the local authorities.
C.—DENMARK.
The following account of the requirements in force
has been received from the Education Department at
Copenhagen :-
There are no special regulations for the artificial
lighting of classrooms, but there have always been
definite rules which are observed for the arrange-
ments in this connection.
Up to the year 1880 open batswing burners were
used in all the communal schools, four in each
classroom and generally a gas lamp by the
master's desk. A classroom, as a rule, has a floor
area of 47 Square metres (487 square feet) and a
height of 3-8 metres (12 feet 6 inches). In 1880
Argand lamps with split burners were introduced.
Between 1888 and 1898 all newly-built schools
were provided with Siemens’ regenerative burners
with ventilators. In 1898 and the next two
following years Auer incandescent gas lamps were
introduced into all Schools, both old and new.
Four of these of 75 candle-power each were pro-
vided for a classroom of 47 square metres floor
space (487 Square feet), corresponding to a pro-
portion of 6-3 candle-power per square metre
(0' 62 candle-power per square foot). The lamps
were furnished with shallow comical reflectors and
eyeshades. This system is still in use in all schools
built before 1908.
Since 1908 power electric light has been installed
in all new schools, 50 candle-power metal filament
lamps with half shades being used. Every class-.
room is provided with four lamps, which are fixed
about 1 metre above the pupils’ desks. They are
calculated to give an illumination of at least
24 metre-candles (2° 5 foot-candles) on each desk.
But as it is found that this system of lighting is
not very satisfactory owing to there being no
reflection from the ceiling and to the deterioration
of the lamps after use, it is proposed to instal five
lamps or to increase the candle-power to 75 for
the two lamps nearest to the master's desk, so
that the total amount of light in each room will
be equivalent to 250 candles.
D.—FRANCE.
The following requirements apply to all maternal
schools :— - - - -
The windows, which should preferably be rect-
angular, and the bays, shall be as large and
numerous as possible.
The lintels shall be situated immediately under
the ceiling so as to give the windows as much height
as possible.
The window sills shall not be higher than 0-5
metre (1 foot 8 inches) from the floor, so as to allow
the pupils to see out, and all precautions shall be
taken to prevent breakage of the glass and other
accidents. - -
(1) Ministerial circular of 14th March 1892.
(*) Ministerial decree of 27th November 1874.
C 4
18
#.
; :
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND worksHOPS:
All windows and their imposts shall be capable
of opening, and dowble windows shall be provided if
the climate requires it. The window fastenings
shall be about 1.6 metres (5 feet 3 inches) above the
floor. - -
The blinds, if there be need for them, should be of
such a kind to intercept the rays of the sum without
Żmpeding the circulation of the air.()
Lighting by a glass roof is forbidden as the
principal source of illumination, but it may be
adopted to secure a complement of light.(?)
So far as possible, electric light shall be used for
artificial illumination. The sources shall always be
so placed that they cannot tire the sight of the
pupils. With this object it is desirable that the
Żllumination should be derived from diffused light,
Teflected from the ceiling. This method of lighting
7s easily obtained by means of inverted reflectors
directing the light on ceilings painted white.(?)
The following requirements are in force in all
primary elementary schools:—
The dimensions of the windows shall be calculated
80 as to provide adequate light for all the desks.
The width of the piers shall be as small as possible.
The windows shall be rectangular or slightly
arched.
The distance between the tops of the windows and
the ceiling shall be about 20 centimetres (8 inches).
The Sills shall be bevelled on both sides and situated
1:2 metres (4 feet) from the floor.
Where unilateral lighting is adopted, the daylight
Tivust come from the left side of the pupils, and the
following conditions must be observed :-
(1) The height of the room shall be equal to
about two-thirds of its height ;
(2) Ventilation openings must be made in the
wall opposite to that from which light is re-
ceived.
In all cases the distance from the wall or walls
from which light is obtained and neighbouring
buildings shall be not less than 8 metres (26 feet
3 inches).()
No windows shall be placed in the wall opposite
the master's desk, nor in the wall facing the pupils.
Lighting by means of a glass roof is forbidden.(?)
E.—GERMAN EMPIRE.
In Prussia, a provision exists that in all classrooms
the window area of a room must amount to one-fifth of
the floor area.
There are no regulations as to artificial light.
F.—HOLLAND.
The following requirements apply to all public
elementary schools:—
The windows must be so placed and arranged
that the classroom is completely and adequately
lighted and all strong light is modified.
They should be placed by preference in the wall
on the left hand of the pupils, and in no case in the
working wall.
The upper part of the windows in the walls must
be capable of being easily opened at all times, whilst
ºn every classroom the lower part of at least one
window frame must be capable of being opened to
its full eatent.
The total area of the window glass in every class-
Toom must amount to one-sixth of the floor area if
the situation is open, and one-fifth if the entrance
of light is obstructed by neighbouring buildings
or trees.
The lower edge of the glass in the windows on
the left of the pupils must be not higher than
1.25 metres (4 feet 1 inch) above the floor, and the
(*) Special instructions in regard to the situation, &c. of
maternal schools (1910), Art. 12.
(*) Ibid., Art. 13. (*) Ibid., Art. 18.
(*) Special instructions in regard to the construction, &c.
of primary elementary schools (1901) Art. 19,
(*) Ibid., Art. 20,
wpper edge must be eaſtended as near to the ceiling
as is practically possible.(*)
The passages and halls must be adequately
lighted. . . . The stairways must be adequately
lighted. . . .(?)
Closets, urinals, and porches must be adequately
lighted.(?) -
All passages, halls, and specially constructed
Tooms used as cloakrooms must be adequately
lighted.() . .
Identical requirements exist also for denominational
elementary schools.(?)
G.—ITALY.
There appears to be no legislation on the lighting
of schools.
H.—Norway.
The following extracts occur in various circulars
from the Education Department —
The windows in the classrooms showld be so
placed that the light enters from the left side of
the pupils. The window area should amount to
at least one-sia,th of the floor area, and the piers
between the windows should be as marrow as the
stability of the building will admit, and should in
mo case ea:ceed 0.9 metre (3 feet) in width. The
lintel of the windows should be rectangular, and
should reach as near to the ceiling as the safety of
the structure allows, and its distance from the floor
should in no case be less than seven-twelfths of the
breadth of the room. The upper window frame
Showld be so arranged that it can be twrned on a
horizontal aa is and be easily opened and shut from
below. The window sills show.ld not be lower than
the tops of the pupils’ desks.
If sufficient light cannot be obtained by this means
windows may be placed in two opposite walls (those
on the left and right of the pupils).
It is convenient to place over the ea;it door (if
this leads to a corridor or anteroom) a window of
the same width as the door and at least 0 - 6 metre
(2 feet) high, so arranged as to be easily opened and
shut on a horizontal aa is from below.
In gymnasiums the window area should amount
to at léast one-eighth of the floor area. The windows
should preferably be placed ºn one long wall only,
and that on the sunny side ; the window sills showld
be at least 1: 5 metres (5 feet) above the floor.(")
Drawing studios should have abundant light.
The windows should be provided with sills not less
than 1 2 metres (4 feet) high wnless the light is cut
off up to that height, and should be carried up as
far as possible to the roof. The total effective
window area should be not less than one-fifth of the
floor area.(7) - r.
The following requirements refer to gymnasia —
The windows should be either very large, situated
in one long wall, and not less than 1 : 5 metres
(5 feet) from the floor, or somewhat smaller, situated
Žn both long walls, 2 5 metres (8 feet 3 inches) above
the floor. - -
The artificial lighting should be electric or gas
light. Fażling these, oil lamps which do not smoke
may be used.(?)
R.—SWEDEN.
All schools (both ordinary and board) must be
situated in Open and healthy places,(*) and it is required
that as regards warming, ventilation, lighting, and
(l) Royal decree of 13th July 1912 (Statute No. 192),
Art. 10. &
(*) Ibid., Art. 12. (*) Ibid., Art. 14. (*) Ibid., Art. 16.
(*) Royal decree of 13th July 1912 (Statute No. 193)
Arts. 8, 10, 12, 14.
(6) Circular dated 23rd March 1886.
(7) Circular dated 1st June 1898.
(*) Circular of 21st April 1897. - *
(*) Laws of December 10th, 1897, par. 53 : February 18th,
1905, par. 57.
APPENDICES. 19
cleaning of school buildings, the headmaster, with the
advice of the school doctor, shall submit a suitable
scheme in accordance with the regulations laid down
by the Board of Education.()
These regulations contain the following references
to lighting, so far as regards Ordinary schools —
Every classroom must be well lighted by windows
of sufficient size and Switably placed. The windows
must admit sufficient light to enable print in ordi-
mary type to be read by a normal eye easily and
without straining in all parts of the room.
The window sills must not be made lower than
1:2 metres (3 feet 11 inches), and the windows must
Teach as near as possible to the ceiling and be made
horizontal at the top.
The piers of the windows must not be too broad
and must be bevelled towards the inside of the
7"OO7??,.
The total window area must amount to at least
one-fifth of the floor area of the room.
The windows of the classroom must be situated
only in the wall on the left of the pupils, when seated
at their desks. Windows must not be placed in the
wall immediately in front of the pupils. Windows
'n the right side wall and the back wall should be
avoided as far as possible, and where they do occur,
should be provided with inside shºwtiers.
Skylights and roof windows are switable only for
technical and industrial rooms and laboratories.
The window frames of all classrooms, whether inside
or outside windows, should be fia!ed on hinges so as
to admit of their being opened for complete ventila-
tion. -
Cwrtains showld be provided, where necessary, as
a protection against direct sunlight. These should
consist of thin, flimsy material, best of whbleached
limen, and should be capable of being drawn either
from the sides, or from below upwards, or from
above downwards, according as the 8wnlight enters
the room.(?)
1. Classrooms.-In the selection of artificial light
sources care showld be taken that these give sufficient
and soft light, without glare and shadows, and it is
fownd that a light source of about 25 candle-power
at a distance of one metre is sufficient for reading
and writing. -
The lamps must be so placed that the pupils are
mot compelled to look either straight at them, or
directly past them. They must therefore be fiated
sufficiently high and be provided, as a rule, with
suitable globes or shades, constructed, for instance,
of opal or ground glass. Switable illuminants are
Čncandescent gas and electric lamps of various kinds,
such as ordinary glow lamps, mernst lamps, and arc
lamps. If arc lamps are used, indirect lighting
should be adopted, that is, the whole of the light
from the lamps is thrown up to the white ceiling by
a screen fiaſed under the lamp. -
If special lamps are used for the illumination of
the blackboard, these must be provided with opaque
shades which throw the light on to the blackboard,
and the lamps must be so arranged that mome of the
pupils are troubled by reflection from the blackboard.
2. Rooms for Instruction in Scientific Subjects.-
Instruction rooms should be placed towards the
sowth, South-east, or South-west, so as to enable
eaperiments involving the use of sunlight to be
carried out. The rooms should have means for
eacluding all light, such as suitable curtains or
shutters. -
3. Rooms for Technical Instruction. — The
windows of technical rooms should, as a rule, be
arranged on the same plan as windows in class-
T"O O'???.S.
For artificial lighting the following systems are
the most switable :-
(i) Incandescent Gas.-These can with advan-
tage be placed two and two on each window pier.
(ii) Electric Glow Lamps.-4 he light from each
lamp is spread over the desks for two or three
(1) Law of February 18th, 1905, par. 60. ,
(*) Board of Education Circular No. 2, dated 14th September
1905, Section II., par. 5.
pupils by means of a reflecting shade. At the
same time the shade protects the eyes of the pupils
sitting behind.
(iii) Electric Arc Lamps.--The arrangement
for indirect lighting has been already described.
These lamps give abundant and evenly distributed
light, and the cost of current is lower than for the
glow lamps. For some kinds of writing eatercises,
however, inconvenience may be caused by shadows.
6. Rooms for Industrial Instruction.—Rooms
situated on the ground floor should be provided with
windows on two, or, if possible, three sides. The
pupils should, during work, receive light from the
Tight side as well as from behind, or both from
behind and from in front. If the room is so situated
that passers-by can see in through the windows, it is
well to furnish the lower portions of the windows
with panes of ribbed glass. If the room is situated
on the top storey, roof windows are preferable. To
ensure 87tificient ventilation in such a room a number
of air shafts should be led up to the ceiling.
For artificial lighting, electrical light sources are
the most convenient in all respects. If glow lamps
are adopted, it is desirable that one should be
supplied to each work-place. The lamps should be
furnished with reflectors so as to throw the light
downwards. If arc lamps are used, two of these
should suffice for the lighting of the room, but it is
desirable to supply four or five glow lamps for work
which requires a stronger light, such as turning,
wood-carving, &c. Incandescent gas can also be
employed ; but it possesses the great disadvantage
that the Zöghting power of the incandescent manile
falls off very quickly, owing to the fine sawdust
present in the air settling partly on the mantle itself
and partly in the fine channels of the burners. The
distribution of glow lamps and gas flames show.ld be
arranged after the work benches and machines have
been placed in position.()
The following regulations refer to Board Schools —
It is of great importance that the wall containing
the windows through which the classroom obtains
7ts principal light should face a well-lighted
quarter. South-east is best. It is true that, with
a southern or south-western direction, the task of
warming the classroom in winter would be
lightened, but, on the other hand, unbearable heat
would ensue in the summer. With windows facing
directly east or west, the sunlight penetrates the
Toom in the morning and evening in an almost
horizontal direction, and causes great inconvenience.
A northern outlook is advantageous in southern
countries, but in Sweden any classroom which had
windows facing that dark and inclement quarter
would be unpleasant.(?) -
The desks must be placed at right angles to the
long side of the room, and must be so arranged
with regard to the light that the children do not
ºreceive the strongest daylight either from in front
or from the right, but in all cases from the
left.(?) . .
Every classroom must be well lighted by suffi-
ciently large and suitably placed windows.
The windows must admit sufficient light, so that
even the furthest parts of the classroom receive
full daylight, but, on the other hand, no more
windows should be installed than are necessary for
this purpose, both on the score of economy and to
dispense to some eatent with the necessity for
artificial heating.
In determºning the amount of window surface—
which may in general amount to 15 to 20 per cent.
of the floor surface—account must be taken both
of the orientation and of the character of the
surroundings, and deviation from the rule can
also be allowed, taking into account the further
arrangements of the building.
As has been already stated (s. 29), the pupils,
when seated at their desks, must receive the light
*-m-sº
(') Ibid., Section W.
(*) General Plans and Specifications for Board School
Buildings (1865), s. 4.
(*) Ibid., s. 29.
20
T) EPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
from the left-hand side. Partly to carry out this
*wle and partly to obtain a pleasant soft light, the
daylight should preferably be admitted from one
side only, through windows along one length of
the room. i
Even a large room will obtain sufficient daylight
by this means, ºf the windows are large enough
and their height Swited to the width of the room.
The distance from the floor of the room to the
wpper edge of the window must in such cases be
not less than half the width of the room, so that,
allowing for a space of one foot in the wall, above
the window, a classroom 22 feet wide must be at
least 12 feet high, a room 24 feet wide at least
13 feet high, and a room 30 feet wide at least
16 feet high.
Since now the height of an ordinary classroom
must not eaceed 16 feet, it follows that in rooms
ea:ceeding 30 feet in width the windows must be
situated in two opposite walls.
The last arrangement of windows, however, is
less convenient, Since the numerous cross-shadows
which arise cause an impression of confusion. In
addition, with this method of lighting the black-
board takes on a bright sheen, which makes the
writing on it very difficult to decipher, and the
pupils engaged in writing ea:ercises turn themselves
first to one side and then to the other, according to
which direction the strongest light falls in.
No windows should be situated in the wall in
front of the pupils' seats in any circumstances,
since the light would them fall right in the
children's faces and affect their sight injuriously.
On the other hand, windows can be introduced
without harm into the opposite gable wall if
circumstances so require.
The windows in a classroom should be larger
than in an ordinary dwelling-room ; their height
should vary from 8 to 11 feet; and their width.
from 4 to 6 feet, according to the size of the room.
The piers between the windows and at the ends of
the wall show.ld be sufficiently narrow to allow the
daylight to be uniformly distributed. Darkness
will always ea;ist behind a pier that is too wide.
When the windows are situated in one long wall
only, then, at any rate, there need be no wide pier8
between the windows in that wall, since the other
three sides of the room supply adequate space for
chdºts, tables, blackboards, &c. In a brick building
the window recesses should be enlarged towards the
Žnside, so as to reduce to a mºnºmºw’m the shadows
arising between the windows.
The windows should reach as near as possible to
the ceiling, whless some ornamentation eaſists. The
height of the wall above the windows or the distance
between the window panes and the swrface of the
ceiling should, as a rule, not eaceed 1 foot. The
ceiling beams should alternate with the windows.
If the window sills are too low, the light from the
lower parts of the window will strike the pupils’
eyes; if, on the other hand, they are too high, the
room becomes dark. To prevent the pupils from
seeing out during lessons and the passers-by from
seeing in, the window sills should generally be
pather higher than in an ordinary dwelling-room.
When the position is good, a height of 3 feet is
sufficient for the sills; but if the school looks on the
street or public road and lies low compared with its
surroundings, the height may be increased to 4 or
4' 5 feet.
Classrooms and all other rooms with fireplaces
should be provided with double windows.
The whole of the outer window frame and at least
one pame of the inner frame shall be fiased on hinges
so as to allow of their being opened when necessary.
For the windows of a classroom, both outer and
Žnner, completely clean and white, that is, clear
white, glass should be used.
As a protection against bright sunlight, either
curtains or blinds shall be adopted. The curtains
must be neither dark nor bright white, but a light
grey or unbleached cloth, so that the glare of the
(*) Ibid., SS. 41–51,
sunshine is removed without making the room dark
as well.
L.—UNITED STATES OF AMERICA.
Specific requirements as to the lighting of schools
are not found in the majority of the States, and
in some there appears to be no reference to the subject
in any form.() . In others, however, definite provisions
are laid down either statutorily or by order from an
authorised department. The following may be quoted
as examples:—(?)
Rhode Island: -
The State Board of Education from time to time
shall approve proper standards of lighting, heating,
ventilating, seating and other sanitary arrange-
ments of school buildings.(*) - -
Vermont : - --
School houses shall conform to the following
detailed requirements :
(h) Buildings shall be so located as to secure
the best light. Particular attention must be
given to this in villages where the school house is
likely to be surrownded by other buildings.
(i) The walls of the room shall be light gre?),
buff, or greenish tint. - -
(m) The windows shall be numerous, large
enough and so arranged as to give ample light to
every part (and corner) of the room. The window
space should be one-fourth of the floor space, and
must be not less, than one-fifth. There must be
no more space between the top of the window and
the ceiling than is required to finish the building,
and the window Sill must be four feet from the
floor. The light must be arranged 80 as to fall
wpon the pupils from the left or left-hand back,
never from the front. There must be curtains
of a grey or buff colour for all windows—two to
each window—hwng in the centre of the window
so that either the upper or lower half, or both, can
be shaded. -
(r) Blackboards shall be placed opposite windows,
never between, and shall be of a dark, lustreless
colour. Lessons placed on the board for pupils to
copy are injurious to the eyes, by reason of the
rapid change of focus required from the distant
board to the paper on the desk ; hence, these should
- be avoided.(*)
Bennsylvania: -
All school buildings hereafter built or rebuilt
shall comply with the following conditions :—
In every schoolroom the total light area must
equal at least 20 per centum of the floor space,
and the light shall not be admitted thereto from
the front of the seated pupils.(')
Ohio : . . . - * -
No wall of any building . . . w8ed for light-
Žng school or classrooms shall be placed nearer ańy
opposite building, structure, or property line than
thirty (30) feet.() - -
The proportion of glass in each class, study,
Tecitation high schoolroom and laboratory “all be
not less than one (1) square foot of glass; 2 - “
five (5) square feet of floor area. . . . . . .
Windows shall be placed either at the left or the
left and rear of the pupils when seated.
Tops of windows, eacept in libraries, museums,
and art galleries, shall not be placed more than
(i) No legislation appears to exist in the following States:—
Connecticut, Massachusetts, Maine, Colorado, Illinois,
Nebraska, Maryland, Oklahama, Kansas, Missouri, South
Carolina, California, Arizona, Nevada.
(2) In addition to these regulations plans have to be
submitted for approval in the following States:—New York,
Iowa, Michigan, South Dakota, North Carolina, Utah, Rhode
Island. -
(3) Public Laws, 1911, ch. 72, s. 3.,
(*) State Board of Health Regulations (1911), s. 7.
(5) School Act (1911), s. 618. .
(*) State Building Act, S. 3.
APPENDICES. , ‘’ 21
eight (8") inches below the minimum ceiling height
as established winder section 7.
The whit of measurement for the width of a
properly-lighted room, when lighted from one side
only shall be the height of the window head above
the floor.()
Louisiana :
Windows and transomes shall be so constructed
that the windows may be lowered from the top and
transomes opened. Every school house must be
lighted in Such a manner as to mºnºmise the eye
strain. Each room must contain of actual surface
of glass in the windows not less than one-seventh of
the floor space.(?) -
Oregon : -
The same regulations apply to schools as to
factories (q.v.). Schools are covered by Grade I.,
Division c.
South Dakota :
In order that dwe care may be exercised in the
heating, lighting, and ventilation of public school
buildings, hereafter erected, no school house shall be
erected by any board of education or school district
board in this State wintil the plans and specifications
for the same, showing in detail the proper heating,
lighting, and ventilation of such building shall have
been approved by the superintendent of public in-
struction.(*)
North Carolina : * ,
£he light, according to the best authorities, should
(*) State Building Act, s. 11.
(*) Sanitary Code, s. 250 (6).
(*) School Code of 1907, Art. XV., s. 237.
come from the rear and left side, or left side of the
pupil only, and the glass surface should equal from
one-sixth to one-fifth of the floor area of the room.
The windows should be set 3 or 3% feet above the
floor, and the window head show.ld come within
12 inches of the ceiling. The school'oom, windows
showld have a 24-inch transome each hºnged at the
bottom, to swing in.()
Texas :
In the public school buildings of Tea as no window
admitting light shall be so placed in a classroom or
study hall that it must be faced by pupils when
seated at their desks. -
All window openings admitting light into class
Tooms or study halls shall not come lower than a
point 3% feet from the floor, and shall eafend to a
point within 6 inches of the ceiling.
The area of clear window surface for the admis-
Sion of light into any classroom, or study hall shall
not be less than one-sixth of the area of the floor
space in said classroom or study hall, and no part
of the said classroom or study hall in which pupils
are seated or required to study shall be at a greater
distance from the window than twice the height of
the top of the window above the floor, eaccept in
cases in which adequate skylights are provided.
The main light in all one-room schools shall come
from the left of the pupils as they sit at their desks,
and in all larger buildings this condition shall be
approaºmated as nearly as architectural demands
and the demands of ventilation will permit.(?)
(*) Plans for public school houses (1911).
(*) Public Schools Act (1913), ch. 130, ss. 1–4.
22 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
APPENDIX IX.
MEMORANDUM ON ACCIDENTS IN FACTORIES.
By D. R. WILSON AND C. C. PATERSON (Joint SECRETARIES).
In order to discover the relationship (if any)
between working with artificial light and liability to
accident, use has been made (at the original sugges-
tion of Mr. L. W. Thomas, of the Statistical Branch of
the Factory Department) of a special return of all
reported accidents for 1913 and part of 1914, in which
the number of accidents occurring each month from the
following causes—
(a) Machinery moved by mechanical power,
(b) Molten metal, hot liquid,
(c) Struck by falling body,
(d) Persons falling,
(e) All causes,
are tabulated for a large number of industries.
From this return the following industries and
causations have been selected for special study:--
Industry. Causation. Reasons for selection.
Textile sº gºs (a), (d) An Organised class
of industry carried
On under approxi-
Imately uniform
- conditions.
Textile (cotton | (a), (b), (c), Localisation, and
Spinning and (d). uniformity Of
weaving). hours of employ-
ment and holidays.
General engineer- | (a), (c), (d) Large size of indus-
ing. try.
Shipbuilding - | (a), (c), (d)
ºsºmeº () º (d) |}special liability to
Drink (except (d) | accident. *
aêrated waters).
Buildings under (c), (d) “Daylight ° indus-
construction. | try.
|
In the application of these figures use has been
made of three methods:—
METHOD I.
Diagrams (A to D) have been prepared, showing
monthly percentages of accidents due to various
causes. In these the accidents from a given cause
in any industry are expressed as a percentage of the
total accidents occurring in that industry from that
cause during the full period of 14 months under com-
sideration.
METHOD II.
Diagrams (E to H) have been prepared, showing
for each month the relative number of accidents due
to various causes. In these the accidents are expressed
as a percentage of the total number due to all causes
occurring in that industry during the month in ques-
tion.
METHOD III. º
In this method, which is based on certain assump-
tions, an attempt is made to calculate the normal
accident rates from each cause during the months when
no artificial light is used, and, by applying these rates
to the daylight period of employment during the
winter months, to estimate the accident rates during
the use of artificial light.
The method is separately considered later.
METHODS T. AND II.
The differences between these two methods may be
expressed as follows:–
Method 1. is unaffected by changes in the number
of accidents due to causes other than the one under
consideration, but it takes no account of the number
of working hours (as determined by the week-ends,
holidays, &c.), nor the number of persons at work (as
determined by the state of employment) in each month
As the significance of these curves depends on the
number of persons employed being constant, tables
showing the state of employment in the principal
industries have been prepared from the returns fur-
mished to the Board of Trade and are appended to this
memorandum. It appears, however, that, except for
a few industries (e.g., docks and shipbuilding), the
changes in employment are without appreciable effect.
In Method II., on the other hand, the effect of the
variations in the number of persons working and the
number of working days is eliminated, but the true
character of the curve may be masked by changes in
the number of accidents occurring in the industry from
causes other than that under consideration.
The special features of the curves obtained on the
principles already explained are given in the following
table and the general conclusions to be drawn may be
Summarised as follows:–
(1) The curves based on Method I. show a general
drop for August, due, doubtless, to the holiday
season, and, in many instances, a sudden rise in
October, for some reason difficult to explain.
(See especially curves 6, 15, 16, 17, 18, and 21).
(2) Generally speaking, the curves possess no charac-
teristic form, eacepting for accidents due to
persons falling. In spite of considerable irregu-
larities, the tendency of these curves is markedly
Concaye, indicating an increase during the winter
months of accidents due to this cause. (See
especially curves 14, 16, 20, 21, 35, 36, 37, 38, 41,
and 42.) The chief exceptions are—
(a) Construction of Buildings (curve 40), which
is practically a daylight industry, and
(b) Docks (curve 39), in which the number
of accidents from other causes probably varies
greatly from month to month.

Accidents.
Numbers and Special Features of Curves.
Industry. State of Employment.* Method I.i. Method II. Remarks.
Causation. .
No. Description. No. Description.
(1) (2) (3) (4) (5) (6) (7) (8)
Textile - º Good generally, but diminishing (a) Machinery 1 None - º º . gº - 22 Curve strongly convex, rising to A higher accident rate in summer,
throughout the year. (Extreme moved by power. a maximum in September, and possibly due to increased pressure
difference 2 per cent.) falling to a minimum in February. of work before and after holiday
- Séa, SOD.
(d) Persons falling 14 | Concave between January and 35 | Concave between January and
November, with minimum in August, with minimum in June
| June. Falls after November. and maximum in August. After
- August fairly constant.
Founding - Fairly constant till July; then a (b) Molten metal || 6 | None. Minimum in September, 27 | None - e. ſº - - This causation is not directly
. sudden drop of 15 per cent. to corresponding to state of employ- dependent on lighting.
September, after which a rise ment.
occurs to normal conditions in (e) Falling object | 8 || None, except steady rise from 29 | None.
November. (Extreme difference September to February, corre-
20 per cent.) sponding to increase in employ-
ment. -
(d) Persons falling 15 || Strongly concave between 36 | Curve tends to rise at either end, The accidents from this cause are
Eebruary and October, with corresponding to the winter months. more numerous in winter than in
minimum in July. - | Maximum in January; minimum Summer,
- t - - in July.
Shipbuilding - || Constant, except for September (a) M achinery | 2 | None - * º - - || 23 | None.
and October, when a sudden drop moved by power. -
of 2 per cent. occurred. (Extreme (c) Falling object || 9 || None - s * {-, - 31 | None. -
difference 2 8 per cent.) (d) Persons fall- 16 || Strongly concave from Febru- || 37 || Strongly concave throughout. Curve 37 shows that in winter
ing. ary to December, with minimum Maximum in February; minimum about 21 per cent. Of accidents
in July. in July. from all causes are due to falls,
and in summer about 17 per cent.
only. * &
Drink (except | Unknown, but probably fairly (d) Persons fall- || 17 | Curve irregular, with maximum | 38 A continuous and heavy fall The size of the premises, the
aêrated waters). constant. ing. in January 1914 and minimum between January and August, with number of vats, stairs, hoists, &c.,
in June. an irregular but marked rise after- and the absence of fast-running
- wards to January 1914. machinery make falls one of the
most fruitful sources of accident.
Docks - - || Only figures for London avail- | (c) Falling ob- || 10 | None - $º E; wº - 31 | None - $º gº tº º - An important source of accident.
able. Employment quite irregular. jects. - - - º
Maximum in January 1913 and (d) Persons fall- 18 Concave from January to 39 || None, except that generally Curve 18 closely follows the
October; minimum in February ing. October, with minimum in speaking the curve is higher in employment chart for London.
1913 and August. (Extreme
difference 14 per cent.) &
September ; then falls slightly
to February 1914.
winter than in summer.
w
§

Accidents.
Numbers and Special Features of Curves.
Industry. State of Employment.” ; e Method I.i. Method II. Rcmarks.
Causation. º .
No. Description. NO. Description.
__ (1) (2) (3) (4) (5) (6) (7) (8)
Buildings un- Irregular. Increase of 12 per (c) Falling objects 11 None. Minimum in January 32 None. Minimum in December; All the curves for both causations
der construc- cent. from January to April; fall | * and December. maximum in February 1914. are quite irregular in form. The
tion. of 6 per cent. from March to June, (d) Persons falling| 19 None. Maximum in December; 40 None. Maximum in February industry is practically a “ day-
and rise of 8 per cent. to August ; - minimum in January. . 1913; minimum in February 1914. light” one, and would not be
then a gradual decline of 12 per - - - t expected to show seasonal varia-
cent. to December. (Extreme tions. ..?
- difference 12 per cent.)
General En- || Constant, but gradually declining (a) Machinery 3 | None - iºn - - - 24 Convex in shape, probably owing
gineering. throughout the year. (Extreme moved by power. . to concavity of curves for other
difference 1 per cent.) causes. Maximum in September;
. . - - - minimum in February. :
(c) Falling objects 12 | None - - tº tº - |33 | None - - - * tººl tºº
(d) Persons falling 20 | Concave from January to De- || 4i | Concave throughout, with maxi- | The form of these curves is very
- cember, with minimum in June. mum, in January and minimum in striking when compared with those
- May. under (a) and (c), especially when
the large size of the industry is
taken into account.
Wood - - | Rises from January to April; (a) Machinery | 4 || None - * sº º - 25 An irregular but very marked
then fairly constant till November, moved by power. rise between May and November.
when a sudden drop of 1 per cent.
occurs. (Extreme difference 2 per
. cent.) - .
All Industries | Very constant throughout the (a) Machinery | 5 | None - t- * . as - 26 | Slightly convex. Maximum in
- year, with maximum in April and moved by power. - - July and September; minimum
minimum in December and Janu- . in January and February 1914.
ary 1914. (Extreme difference less (b) Molten metal 7 | None - - - *s - 28 Almost constant,
than 1 per cent.) (c) Falling ob- 13 Concave between March and 34 || Almost constant.
jects. - October, with minimum in July. - }
(d) Persons fall- 21 Strongly concave from Febru- 42 Concave throughout, with mini- Curve 42 indicates that in May
Ing.
ary to October, with minimum
in July.
mum in May.
11 : 5 per cent. of all accidents are
due to falls, compared with 14 per
cent. in January.
*.
* Based on Board of Trade Returns (see Addendum (p. 27)).
f No account is taken of the month of August on account of the effect of the holiday season.
&
ſº
MONTHLY V ARIATIONS IN Acci D ENTs.
M ET H O D I.
Showing monthly percentages of all Reported Accidents in certain indust–
ries due to various causes during the period of 14 months from January
1913, LG February 1914. - - s
(7% e accidents due to each cause in each industry are expressed as a percent-
age of the tota/ accidents due to that cause occurring %; %; #jãº.,4%%
period of 14 months). D I A G R A M A
é. Accip Ewrs cause D BY MACH (wer Y M oved BY ME.ca Awcal Power.
n -
8
A || Textile |
| n dustries
(10,359)
7 AES- / \ Z" Ship building
/ NZ ^^ ( 2, 5 O 2.)
7 |_2^ *****. / N General Engineering
r Sr. N/ N_i (14,052)
- " * I - / ** wº
7 /\ - A / \ (3, 4-82 )
V. De C. Jan. Feb.
| 9 |4-.
G ----
8
| ALL i NDUSTRE FS 5
7 - (54.975)
| -
3 * |
Aug. Sep. Oct. No
Jan. Feb. Mar. Apl. May. June. July.
| 9 || 3.
D : A G R A M B .
Acc/24:/v7's caused a Y. M. o. TE/w META 4 of 4 or 2/9 of 2.
9. | tºs - - I *
|A | Al / 6
\ / \ _-N /N 7 Founding of Metals
7 . * i
ſ Y Yºr \ S--→ (3, 506)
7
(8.581)
Jan. Feb. Mar. Apr. May. June. July Aug. Sep. Oct. Nov. Dec. Jan, Feb.
1913. # 9 4. . .
(7he figures in brackets give the total number of accidents concerned.)
Jº-4/3, 1630/2. 2500. 7. J5, Malby & Sons,lith.



D I A G R A M C .
A C C / D E // 7° S CA U S E D B Y F A L. L / W G O B J E C 7"S.
Per
C ent
S - - t n v - *
8 - - /N -R , t 8
FSD/ N - \ / Founding of Metals
\ - - (1, 4-5 es)
6 - | w
f Ship build in g
/ - - - - (4., O 9 s )
|O
Docks
(3, 3.5 O)
- - - - Construction of
8 | \ - - A-TN - Build in g s
| - \– - - ( 4-2 4- )
>
|2
General Engineering
(8, 2.29)
—-i-º-
_* ALL INDU stries|3
(32.090)
|
G - \ ..." - -
Jan. Feb. Mar. Apl. May, June, July. Aug. Sep. Oct. Now. Dec. Jan. Feb.
| 9 || 3. º: - |S 14- .
(The figures in brack ets 9/ve the tota / number of accidents cancerned.)
... 34.73. reso/2. 2.54369, 7... ſº . ... . . Malby & Sons Lith


UTR GTR. R. W. L.
r
De ſ” A CC/D E W 7 S O U E TO PER SO N S FA 1. L / // G .
S ... . . . . . . . . . ... ' ... . . - - | -n
3 Yº - _^ -
--~~. T N - yr N – All Textile
7 – 4– * - *> _ Industries
- Y— \ 2 / ` (2,094.)
& Y ——
8 / YA - - -T-- Founding of Metals
7. - /NS . ^s (6 e)
/N - 2^ | |6
8 - - *— ——
'º- - - - * - Ship building
. 7 / ^ - / \ 2 (3, 9 e 5)
- 10 r- - - — — =–r- — -
s - - - - -
- | - - V ſ Drink
7 H /N / \ - (6 7)
|8
Doc k s
Nºts - / - (2,292)
TTTTTTT A I9
8 /\ - ^1 - - / \ construction of
\|| 2 || HS 7 |\|| "..."
General Engineering
(4,078)
2
ALL INDUSTRIEST
(25.795)
G 4– . . "
Jan. Feb. Mar. Apr. May. June. July. Aug. Sep. Oct. Nov. Dec. Jan. Feb.
- | 9 || 3. ". }S 4-.
(The figures in brackets give the total number of Accidents concerned).
34-19. 1650//2.2soo. 7. Is Malyssonslith.






M ET H O D II.
Showing, for each Month the relative number of Accidents due to various causes in
Certa'ſ m Industries during the period of 14 months from January,1913 to February, 1914.
( The accidents due to each cause in each industry are expressed as a peri
centage of the tota/ 3 ccidents due to aſ causes occurring in that industry during the
month in question.) -
D I A G R A M E.
A CC / DEN 7S CA U S A. D B Y /M A C H / /V E A Y M O v E D B Y ME CA; A /w/ CA/. Power.
Per ,”
Cent. -*
*H 2NT/N - – 22
so, — Y N/ - . Y, Aſ | Textile
- N |. - | | . t * - | | n du stries
4.8
4- 3
23
Shipbuilding
General Engineering
3 O
| AVN | *
isºr \ /-1 were
G 2 \|/
2.8 - - º - #4 n -
'S - - —º- 26
2 (5 # * . . . . ALL INDUSTRI ES
<!- |S –a–
Jan. Feb. Mar. Apl. May, June, July. Aug. Sep. Oct. Nov. Dec. Jan Feb.
| 9 || 3
| | S 4. .
D I A G R A M F.
A CC/DE/WTS CA U SED BY MOA. TE/W M ETA L OF HOT L / Q U / D.
4-C) - - * —w- - r - –-r-
38 /\ g 27
Al/\| | | |A|\| _ "º"
t / | N/ |\|_2
3 4- \-f
ALL- industries28
! . . " º-º-
Jan. Feb. Mch. Apl. May. June. July. Aug. Sep. Oct. Nov. Dec. Jan. Feb.
- | 9 || 3. | 9 || 4 .
34/3, 1650/2, 2500. 7. 15. w Malby & Sons,Lith.









D I A G R A M G .
A C C / DE W 7 S C A U S A. D. As Y FA / L'/ /V G O B J E C 7" S.
Për
C ent
29
Found in g of
M et a s
22
21-i-N _*\ /* 3O
"sy - vTS/ —s / Ship build in g
2. * 3|
Doc k s
24.
||
|| || TNT /NI/N Construction of
|| \ N/ -> ~ - / Build in g s.
32
/\\
! 3 - 2^ - } General 33
...t-r N-sº TS 2. Eng in eering
I 3 | - i. -
34
|ALL INDUSTRIES
4-19. 1350//z. 2500. 7. 3. Malby & Sons,Lith.



D I A G R A M H .
Per
Cent,
Acc/D ENTs ou E To PERSows Fall/wa.
| 2 -
| | A.
st—ts *~ 2^s. - - tº-f All Textile 35
N_- -
In dustries.
lºt is As Zºº. } 36
-H / N Founding of Metals
37
Shipbuilding
38
D r in k
39
Docks
4O
Construction of
Build in g s .
NI/ \
3 O O
te
gº
28 W
4|
General
Engineer i ng
| - ar e —- -** ſ *w-r- ºr -
- - - 42
| 2 ALL INDUSTRIES
| }
May. June. July. Aug. Sep. Oct. Nov. Dec. Jan Feb.
| S 13
Jan. Feb. Mar. Apl.
| S 14.,
34-1s. 1650/2. 25 OO, 7. / 5.
Malby & Sons. Lith.


APPENDICES.
25
METHOD III.
.*
S
S.
Approximate computation of Accident Rate in 1913; (a) during Daylight, and (b) during Artificial Light.
The following assumptions are made :-
(1) For all industries except engineering the hours
of work are taken as 10 per day, viz., 6 to 8;
8.30 to 12.30 ; 1.30 to 5.30.
(2) In the case of engineering the hours are
assumed to be from 7.0 to 8.30; 9.0 to 1.0 ;
2.0 to 5.30, with an average of overtime in 1913
for all workers of one hour a day, from 6.0 to
7.0 p.m.
(3) Artificial light conditions obtain from half-an-
hour before sunset until half-an-hour after
sunrise.
(4) On account of holidays the month of August
is neglected altogether. Easter, Christmas,
and Whitsun Bank Holidays are allowed for.
(5) As for practical purposes no artificial light
conditions obtain from April to September
inclusive (five months excluding August), the
average number of accidents per hour during
this period is taken to represent the accident
rate per hour under daylight conditions only.
The total number of accidents from all causes
from April to September 1913 (excluding August)
was 73,387, or 61.3 per hour. This, therefore, repre-
sents the normal accident rate under daylight con-
ditions, and is the rate which is assumed to hold
during daylight hours in the winter months. The
accident rate during the hours of artificial light which
obtain in the six winter months can then be deduced
for each industry.
Working on assumptions (1) and (3), the working
hours of daylight and artificial light for all trades but
engineering, during the five summer and six winter
months of 1913 are as follows:—
- jor Artificial
---------- Daylight. Light.
Summer (April to September, 1,196 ()
excluding August). -
Winter (January to March 999 393
and October to December).
The total number of accidents during the six
winter months was 92,265. Assuming the above acci-
dent rate of 61: 3 per hour for the hours of winter
daylight, and allowing for the slightly different hours
of work in the engineering trade, we have –
- Accidents.
Total
*=s Accidents. During During
uring Artificial
Daylight. Light.
Winter months - 92,265 61,405 30,860
|
Therefore, the accident rate in all industries and
from all causes in 1913, during the hours of artificial
light, was 79's per hour, as against 61 a per hour for
daylight, an increase of 29 per cent.
By the above method of computation the accident
rates from different causes in the various industries
have been determined, and are shown in the appended
table :-

|
| Total Accidents. g Accidents during Per-
Rate Light between
Summer per Hour * Daylight
Causation. Industry. Months | Winter | (deduced - Accident and e
aś, Months. sº Daylight. Artificial. º *f;
August). Months). Pºr Flour. Aacident
- Rates.*
(1) (2) (3) (4) (5) (6) (7) (8) (9)
*
ſ Textile - - - 3,700 4,726 || 3:09, 3,089 1,637 || 4 - 16s + 35
o Wood - - - || 1,225 | 1,557 | 1.02 1,023 534 || 1:35s + 33
Mºhinº | hiphilding . . . . . . . d.º.º. "º ºf o.º. "I",
Y.” Engineering . . 5,134 6,192 || 4-26, 4,319 1,873 || 4.94, -- 16
power - - || Other industries - || 8,958 10,794 || 7-48, 7,475 3,319 || 8 440 || -- 13
U All industries - | 19,934 24,326 16-62, 16,672 | 7,654 | 19:64, + 18
Founding . . . 1,275 1,505 || 1:06, 1,065 | | | }. + 5
e a; º: - iº 2 *
Molten metal º Other industries 1,810 2,236 || 1: 514 1,51 º 1 842 + 22
All industries - 3,085 3,741 2.58 2,577 1,164 || 2: 962 : + 15
T Founding - - 552 609 || 0:46, 461 148 || 0.37; ; – 18
Shipbuilding - - 1,549 1,798 || 1:29, 1,293 505 || 1 - 28, — 8
& Docks - - - || 1,139 1,506 || 0 '95, 951 555 || 1:42, + 49
Sº..." "4 Bing. . . . . . . . . . . . . . ; 36 || 0 - 092 – 33
bodies - - - Engineering - - || 2,849 3,645 || 2:36s 2,400 | 1,245 || 3:28, + 38
Other industries - 5,048 || 6,576 || 4 - 2, 4,216 2,360 | 6′00 i + 42
. U All industries - || 11,302 || 14,308 9:43, 9,459 4,849 | 12:46, + 32
* A positive sign indicates that the accident rate is greater by artificial light than by daylight.
26
ON LIGHTING IN FACTORIES AND workshops:
DEPARTMENTAL COMMITTEE
tº * g Pe?'-
Total Accidents. . * Accidents during 2
º: Winter Months. Artificial %
Rate Light between .
Summer per Hour Accident Daylight
Causation. Industry. Winter (deduced and
Months from g & ſº tº Rate | Artificial
(ex- Months. Summer Daylight. Artificial. —- Jight
cluding Months). per Hour. Anºiant
Augu St. Rates.
(1) (2) (3) (4) (5) (6) (7) (8) (9)
sº
ſ Textile - - - 694, 980 || 0:58, 580 400 | 1.01s || -- 76
Founding * t- I93 287 0 161s 161 126 0.32, + 99
Shipbuilding - * 1,276 1,898 1.06s 1,065 833 2 : 12 + 99
Drink - tºº º 202 270 0 - 160 169 101 0.25, + 52
Docks - s wº 715 1,072 0. 59s 598 474. 1 20s + 102
Persons falling - 4 Building tº tº 274 330 || 0 22, 229 101 || 0:25, + 12
Engineering - º 1,334 1,895 1 10s 1,107 788 || 2:08, + 93
Other industries not 3,893 5,240 3 253 3,250 1,990 5 : 06, + 56
specified. *
\- All industries - 8,581 | 11,972 7:16, 7,159 4,813 | 12:32, + 71
ſ| Textile - º tºº 7,380 9,744 6 - 17 6,165 3,579 9 II + 46
Wood - tº- ſº 1,871 2,320 1 : 56 1,563 757 I - 93 + 24
Founding of metals 3,562 4,217 2 - 98 2,976 1,241 3 - 16 —H 6
Shipbuilding - wº 7,355 9,094 6 - 15 6,144 2,950 7' 51 + 22
T) rink - sº cº 965 1,233 () - 81 806 427 1 - 09 + 35
Docks - º * 4,052 5,402 3 - 39 3,385 2,017 5 : 13 + 51
All < Buildings under con- 833 926 || 0 - 70 696 230 || 0 - 58 – 17
CallS6S - tº struction.
Engineering - - || 16,570 20,838 13.76 13,942 6,896 | 18:20 + 32
Remaining indus- || 30,799 || 38,491 25' 75 25,728 12,763 32.48 + 26
tries not sepa- -
rately scheduled.
U All industries - || 73,387 92,265 61:27 | 61,405 30,860 79-19 || + 29


ACCIDENT DATA IN COTTON INDUSTRY ONLY.
This Industry has been considered alone because the hours of labour are more whiform and are
more definitely known.


Total Accidenrs. Daylight Accidents during Artificial P%." -
Summer * |Bate Winter Months). Light between Daylight
Causation. Months Winter (aº Hºom Accident Rate and Artificial
º Months. Summer Months). Daylight. Artificial. per Hour. Lig *:::ºften
(1) (2) (3) (4) (5) (6) (7) (8)
Moving machinery 2,486 2,811 1815 1,813 998 2 540 + 39
|Hot metal e- * 130 122 0.09, 95 27 0.07, — 25
Falling bodies - tº 266 224 0.194 194 30 0.07, — 59
Persons falling - º 490 620 0 35s 358 262 0.69, + 93
Other causes - tº- 2,038 2,510 I 489 1,488 1,022 2. 595 + 74
All causes - *- 5,410 6,287 3.95, 3,948 2,339 5-97, + 51
It will be seen that, whilst in all the tables there is
a general increase in the accident rates for the period
of artificial lighting, the increase is especially marked
in the case of accidents due to persons falling. The
smallest increase occurs in the case of construction of
marked increase in the rate for accidents occurring
in winter on the surface.
Average Fatal Accidents per Month.*
buildings, for which, being a daylight industry, no ~~~~ 't : vs. 4-ran- Percentage
j is to be expected. y11g y --> Summer. Winter. Diff.
An attempt has been made to obtain similar data
for accidents in mines, in which work is carried on in 1912:—
artificial light throughout the year. Unfortunately, timderground - 110 88 —20
no such statistics are available, but a return of fatal §: ſº gºt 14 18 +3 9
accidents in mines (differentiated as “surface ’’ and
“underground") is published monthly. 1913 :— -
These have been collated for 1912 and 1913 inderground . 91 89 — 2
(eliminating anomalous returns) with the following ś Er s 11 - 2 16 - 2 +45
result :— - -
It will be noticed that underground, where the
lighting conditions are uniform, the accident rate is
less in winter than in summer, whereas there is a
3rd June 1914.
* The figures for March and April 1912 and October 1913 being affected by the coal strike and the Welsh disaster
respectively, have been neglected.
APPENDICES. ~ . - 27
ADDENDUIM.
CONDITION OF EMPLOYMENT IN VARIOUS TRADES.
A. Based on Returns from Trade Unions of Percentage
of Members Unemployed.
Percentage of Members Unemployed.
Year and Month.
Ship- Engi- WOO(l All In-
building. neering. dustries.
1913.
January - fº 2 : 7 1 - 6 3 - 5 2 - 2
February - s 2 - 3 1 : 5 2 - 7 2 . ()
March - --> 2 : 6 I - 5 2 - 4 1 - 9
April º gº 2 - 7 1 4 1 - 7 1 - 7
May * tº- 2 - 6 I 8 1.7 1 - 9
June gº e- 3 - 2 2 - 1 I - 9 1 - 9
July - " - 2 - 8 1 - 9 2 - 3 I - 9
August - * 2 - 9 1 - 9 2 . () 2 . ()
September tº- 4 - 9 2 - 2 2 - 2 2 - 3
October - * 3 - 9 2 - 2 2 - 5 2 - 2
November -º 2 - 8 2 - 1 2 - 3 2 . ()
December tºº 3 : 3 2.7 3 : 3 2 - 6
1914.
January - ſº- 2 - 8 2 - 4 3 - 4 2 : 6
February - - 2 - 2 2 - 4 2.6 2 : 3
B. Based on Returns from Employers of Persons
Employed.
Average
Increase (+) or §.
Decrease (–) over emplo €1. d
preceding Month. tº.º
Year and Month. only).
Textile. sp bo
# # Docks.
All. Cotton. 5 E
| £ £a
1913.
January - & --- * *=} — | 16,700
February - —0-06 || 0-0 | +0.8 |-|-3:8 || 14,390
March - - —0'08 || 0-0 | +1.5 |-|-2-1 || 14,740
April - - —0:02 || +0.3 | +0.6 |-|-4-7 || 14,950
May iº - +0.03 || 0-0 | +0.1 |-|-0-1|| 14,573
June ſº - —0: 21 || 0-0 | –1.1|–6.3 14,627
July sº - —0 25 —0 2 —0.7 |-|-2-3 || 14,712
August - - –0 15 +0.1 —6 1 | + 5° 5 || 14,300
September - —0 21 —0 5 —9' 0 || –0 3 || 14,512
October - - +0: 21 +0.3 +7-6 ||—2.9 15,822
November - —0 26 || –0 1 |-|-3-3 || –3.4 15,792
December - —0 29 || –0 1 || --1-9 |–5 7 || 15,385
1914. -
January - - —0 : 43 —0 4 —0.1 || ? 15,187
February - i +0 05 —0 3 |-|-0-2 ? 14,800
|

APPENIDIX X.
The INFLUENCE of LATERAL ILLUMINATION on VisuAL ACUITY.
By J. HERBERT PARSONs, M.B., D.Sc. (Member of the Committee).
Reprinted from the Royal London Ophthalmic Hospital Reports, Vol. XIX., Part III.
GoFTHE, in 1810, said that “the eye sees no form,
“ inasmuch as light, shade, and colour together con-
“ stitute that which to our vision distinguishes object
“ from object, and the parts, of an object from each
“ other.” If we include variations in brightness or
luminosity in the generic term “colour,” it may be
said, with Clerk-Maxwell, that “all vision is colour
“ vision, for it is only by observing differences of
“ colour that we distinguish the forms of object,” or,
as Hering puts it, “our visual world (Schwelt) consists
“ essentially of differently presented colours, and
“ objects, as seen, that is visual objects (Sehdīnge), are
“ nothing but colours of different nature and form.”
Hering has emphasised the importance of memory in the
common, but erroneous, attribution of colours to the
objects themselves, implying that the colours are
properties of the objects. It is easy to show that the
apparent brightness and colour of objects can be
altered within a wide range without disabusing our
minds of the opinion that the colours are inherent
properties of the objects. Thus the paper of a book
appears white and the print black, whether we read it
in the morning or at mid-day, or in the evening. Yet
Hering has shown by accurate measurements that the
print may actually reflect more light at mid-day than
the paper did in the morning. In this case the ratio
of the intensity of the light reflected from the white
paper to that of the light reflected from the black
print remains constant under variations of illumination,
and a similar constancy, within wide limits of illumina-
tion, is retained by the eye by means of suitable
physiological adaptation.
In common with other senses, discrimination of
stimuli depends upon differences rather than upon
a 30030
absolute values, a fact which is expressed by Weber's
law that the just appreciable increase of stimulus bears
a constant ratio to the Original stimulus. For white
light Fechner could distinguish a difference of 1/100,
v. Helmholtz 1/167, of the light intensity.
Cobb has published some striking figures showing
the enormous range of brightness to which the eye has
to respond under some quite ordinary conditions of
artificial lighting. “A perfectly diffusing surface with
“ an illumination of 20 metre-candles upon it has a
“ brightness of 20/T = 6' 35 candles per square metre.
“ The tungsten filament which illuminates it has a
“ brightness of 1 64 candles per square millimetre
“ (Ives and Luckiesh), or 1,640,000 per square metre;
“ that is, a brightness 258,000 times as great as the
“ surface it illuminates. . If we go back in history a
“ little and revert to the now humble fish-tail gas
“ burner, we find that it has an intrinsic brightness of
“ 0:004 candle per square millimetre, or 4,000 per
“ Square metre, still 630 times as bright as the surface
“ illuminated. The frosted tungsten lamp is still
“ brighter than this, giving off 9,300 candles per square
“ metre, and being 1,460 times as bright as the white
“ surface. The three sources thus have respectively
“ 258,000, 630, and 1,460 times the brightness (as it
“ effects the eye) which the object illuminated can
“ possibly have otherwise than by specular reflection.”
Of the light which falls upon white paper about 80 per
cent, is reflected, while a paper made as black as possible
reflects about 4 per cent. Printed letters which reflect
one-twentieth or less of the incident light on the paper
appear “black” on a “white ” ground.
The influence of lateral illumination of the eye on
visual acuity is one of considerable practical importance.
D
28
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
The disagreeable effects of a bright light in the field of
vision are familiar to everyone, but the cause of the
distress, and how far it is seriously deleterious to the
dyes are points which have proved difficult to discover.
Theoretically various factors come into play, such as
alterations in the size of the pupil, alterations in
contrast (spatial induction), and fatigue. As regards
contrast, if the light source is screened from the test
object, but not from the eyes, the illumination and
the objective contrast between the object and the
background remain unchanged. Subjectively, however,
the conditions are altered. Owing to the oblique
incidence of the lateral light the media of the eye
are flooded with light, partly transmitted through the
sclerotic as well as through the refractive media and
partly reflected from the various refracting surfaces,
and thus unequally distributed. The conditions are
complex and it is scarcely possible to foretell the
effects.
Sewall*(1884) found that lines ruled on a card were
visible at a greater distance when light from the sky
was thrown into both eyes from the side than when
peripheral light was excluded by a mask. He ex-
plained the result on the basis of the red light trans-
mitted through the sclera and vascular membranes
Diminution of the pupillary aperture might account
for it. - - -
Urbantschitscht (1883) found vision for details
increased when his eye was exposed to light as com-
pared with when it was screened. With dilated pupil
and paralysed accommodation there was apparent
brightening of the test object, but he does not say that
the appreciation of details was increased. The appa-
rent brightening may be attributed to scattered light
(Cobb).
Schmidt-Rimpler; (1887) focussed an electric lamp,
filament on the sclerotic. With low illuminations
even in atropinised eyes, there was increased acuity;
with high illumination, diminished. After working all
day with the microscope he found that at night he
could read better if the light from the lamp was
shaded from the eye. He found that there was no
improvement with lateral illumination in most
diseased conditions (neuritis, atrophy, cataract, glau-
coma), but some improvement in a case with vitreous
opacities.
The first exhaustive experiments on the subject
were commenced by Uhthoff$ (1885) and completed
under his direction by Depène|(1900). The test objects
were numbers illuminated with 100, 4:938, 2.441,
0.938, 0 - 610 or 0.133 normal candles. The size of
the lateral retinal image was 0-441.78, 0.216475,
0-11045, or 0.03976 square mm., i.e., in the proportions
of 100 : 25 : 9. The intensities of the periphal lights
were from 0-31244 to 53' 606 normal candles. Depène
found that when the test object was sufficiently well
illuminated to give vision equal to 1:25, i.e., about
five normal candles, or more, lateral illumination
caused increase in visual actuity. At lower illumination
of the test object diminution of visual acuity was
greater: (1) the lower the illumination of the test
object; (2) the Smaller the angle made by the lateral
light with the line of vision; (3) the greater the intensity
of the lateral light ; (4) the greater the retinal area
stimulated by the lateral light. The improvement
with high illumination was attributed to constriction
of the pupil, since no improvement occurred when
mydriatics or miotics were used. , Diminution of acuity
was attributed to changes in the adaptation of the
retina. No difference was found whether the lateral
light fell on the sclerotic or pupil alone or on both.
Hummelsheim (1900) attacked the problem in a
somewhat different manner, and his results, though
apparently contradicting Depène's, in reality supplement
* Sewall. J1. of Physiol., W., p. 132, 1884.
i Urbantschitsch. Arch. f. d. ges. Physiol., XXXI.
p. 28), 1883.
i Schmidt-Rimpler. Bericht d. XIX. ophth. Gesellschaft,
Heidelberg, 1887, p. 76.
§ Uhthoff. Bericht d. IX. internat, ophth. Congress
Utrecht, 1899. - -
| Depène. Inaug. Dissertation, Breslau. 1900. Klin.
Monatsblatt f. Augenhkde, XXXVIII., pp. 289, 390, 1900.
them. His test object was lighted from behind and
was situated in the middle of a large grey Screen
opposite the window of the room. Thus the peripheral
illumination of the retina was uniformly reflected
daylight. It was varied from 0 to 200 metre-candles.
The visual acuity showed a gradual rise, which was
diminished, but not abolished, by mydriatics and
miotics. Hummelsheim explains the increased acuity
which occurs independently of constriction of the
pupil by Hering's theory, viz., that it is due to spatial
induction.
Borschke” (1904) used a test object illuminated by
a lamp placed a distance (m) behind it, and surrounded
by six lamps which acted as the peripheral light.
The distance of clear vision was first determined with
the dazzling lights off. These were then turned On,
and it was found that the illumination of the test
object had to be increased to make it legible. The
ratio m to n, the shorter distance of the illuminating
light from the test was regarded as the measure of
the disturbance produced by the lateral illumination.
The ratio of m : m was found to be approximately
constant (1-9 to 2 5), and Borschke concluded that
the effect was entirely due to scattered light, chiefly
by the lens fibres. With a focal lateral light it was
immaterial whether the image fell on the nasal or
temporal side, or on the blind spot. Heymansh (1901)
found that vision was unaffected if the lateral image
fell upon the blind spot, but he worked with thres-
hold stimuli, so that the results are not directly
comparable. .*
Tschemolossoff. (1904) found that that the visual
acuity might diminish or increase under lateral illumi-
nation. Diminution occurred when the test object
was feebly illuminated, and varied directly with the
intensity of the lateral light and inversely with the
angle of obliquity of that light. Increase occurred
when the test object was well lighted or even lighted
to excess. Diminution of acuity is due to the actual
image of the lateral light on the retina, to diffusion
of light by the media of the eye, and to contraction
of the pupil causing decrease in the amount of light
entering the eye. Increase of acuity is due to contrac-
tion of the pupil also, as well as to excitation of
retinal sensibility by feeble oblique illumination.
Central sensibility to colours is diminished more, the
stronger the lateral illumination and the less the
contrast between object and background. When the
direct illumination of coloured objects is diminished,
they are less well distinguished even without lateral
illumination. Two oblique sources of light at different
angles diminish the appreciation of feebly illuminated
objects without manifesting any simple addition of
effects. When one eye is illuminated obliquely the
visual acuity of the other diminishes according to the
same rules as with uniocular vision, but to a less degree.
Binocular central vision diminishes with double oblique
illumination, but less than in the case of uniocular
VISIOJ1.
Cobb$ (1911) has investigated the subject with great
care and his paper is the best which has yet appeared.
He used an extremely ingenious test object, invented
by Ives. It consists of two plates of glass, ruled with
240 black lines to the inch. When these are placed in
apposition and illuminated from behind, lines of various
breadth can be made to appear by rotating one of the
plates so that the ruled lines of one plate form angles
of various sizes with those of the other. The test
object can thus be varied at will without altering the
intensity of the illumination, The lateral light was
attached to the arm of a Wundt periometer, i.e., at a
radius of 1 metre. By an ingenious method the effect
of lateral illumination was compared with the effect of
throwing a haze over the retinal image of the test
object. Cobb's conclusions are as follows:—
(1) Light from a bright source entering the eye
reduces the visibility of an object the more, the
* Borschke. Z. f. Psych. u. Physiol d. Sinnesorgane,
XXXIV., p. 1, 1904. XXXV., p. 161, 1904.
i Heymans. Z. f. Phych. u. Physiol, d. Sinnesnorgane, .
XXVI, 333, 1901.
| Tschemolossoff.
CXXXII., p. 303, 1904.
§ Cobb. Amer. Ll, of Physiol., XXIY., p. 76, 1911.
West Ilik. opht. 1904. Ann. Oc.
APPENDICES.
29
brighter the source, the lower the brightness of
the object, and the smaller the angle subtended by
the two ; except that when the test object is very
bright, lateral illumination may cause increased
visual acuity.
(2) Under a condition imitating the worst practical
condition for reading—the light at 10° from the
visual axis, equal illumination of the eye and test
object (black letters on white ground)—the reduc-
tion in visual acuity is negligible at any intensity
of illumination. -
(3) The retinal image of the light is a negligible
factor in the depression of visioi, at least for
angles of 15° and over, since other conditions
being equal, it is indifferent whether the image
falls On the blind spot or on sensitive portions of
the retina.
(4) The depression of vision is due to light which,
by reason ef reflection or diffusion, partly from
imperfect transparency of the eye media, is
scattered over the retina upon and near the image
of the object. -
(5) Visual acuity behaves in general, but not wholly,
the same with (a) illumination of the eye from a
lateral source, and (b) a haze of light thrown over
the rod-free central retina (subtending 2° in the
visual field) with proportional variations in the
light flux in the two cases.
(6) The disagreement between the two sets of
results just mentioned must be due to changes in
the sensibility of the part of the retina concerned
in vision of the object, induced by the scattered
light in the case of lateral illumination, falling
on the retina not on but about that part, and
probably not further away from it than 15°
measured in the visual field (the remoteness of
the blind spot).
(7) There is no parallelism between the depression
of vision for detail on the one hand and discom-
fort and other visual disturbances classed under
the head of “glare’ on the other hand, resulting
from a light source in the field of vision.
In his last conclusion Cobb agrees with Borschke,
who says, “The unpleasant feeling of dazzling (Blem-
“ dwng) and the disturbance of vision produced by
“ dazzling are totally different things, and need by
“ no means necessarily occur to the same extent at
“ any given time.” Cobb throws out the hint that
the discomfort may be associated with the eye move-
ments." -
Cobb (1913–14)* has made a further series of
experiments in which the test object was the same as
before, but the whole of the peripheral field of vision
was either dark or filled with white light. A wooden
cube of 1-metre sides was constructed, the inside corners
and edges being cut off by oblique surfaces tangential
* Cobb and Geisler. Psychol. Rev., vol. XX, p. 425, 1913.
Cobb. The Lighting Journal, New York, April 1913.
Cobb. Trans. of the Ili. Eng. Soc., New York, June
1913.
Cobb, Psychol. Rev., vol., XXI, p. 23, 1914,
to an inscribed sphere, so that the whole 26-sided figure
approached the shape of a sphere. The inside was
painted white. In one of the vertical sides of the cube
an opening was left for the observer's face and head-
rest. In the obliqne surface directly above this opening
was a sheet of milk glass, behind which was a 100-watt
tungsten lamp, illuminating the white interior.
Opposite the face opening another smaller opening was
made through which the test field could be observed,
The test object was 180 cm. from the eye.
Experiments were made to estimate the effect of
peripheral illumination on visual acuity, and on the
discrimination of differences of brightness in the two
halves of the test field. It was found that different
individuals may show fairly wide differences in their
vision of objects of very low brightness, both with and
without bright surroundings. In spite of such individual
differences the relative changes in visual capacity caused
by differences in surroundings were found to be on the
whole in the same direction in cases of the same
change in the conditions. For objects of relatively
low brightness the presence of a surrounding field of
relatively high brightness has the effect of lowering
the capacity of vision both for detail and for brightness
difference. In the case where the snrrounding field
was slightly brighter than the test object visual
discrimination was found to be actually better both as
regards visual acuity and brightness difference than
for a physically identical object seen in dark sur-
roundings. Surroundings of a brightness about equal
to or less than that of the test object show no
consistently better or worse results than dark
surroundings with the identical test object.
Comparison of the visual acuity and brightness
difference curves under parallel conditions shows that
as the brightness of the test object is reduced the
brightness difference limen usually at a fairly definite
point takes a rather abrupt rise. Visual acuity on the
other hand, while always showing a slight progressive
diminution beginning at the very highest brightness
under a similar change of conditions, never undergoes
such rapid decrease as differential sensibility. Cobb
attributes this fact to the dependance of the dis-
crimination of fine detail upon a physically perfect
image on the retina and accuracy of fixation. Visual
acuity therefore varies less under the influence of
contrast than does differential sensibility because the
retinal image is always equally perfect.
As contrasted with the visual acuity, differential
sensibility depends mainly upon retinal conditions, and
to a very minor degree upon perfect retinal images.
The essential difference is that in the case of visual
acuity estimation the brightness difference of the parts
of the test object is gross, while the areas involved are
minimal. On the other hand in the estimation of
differential sensibility by simultaneous presentation
the areas of the fields compared are gross while the
brightness difference is minimal. Hence small
irregularities in the formation of the retinal image
have little effect, but the condition of adaptation,
temporal and spatial induction are prepotent factors.
Spatial induction, produced by alteration in the
surroundings, was found to be far more significant for
differential sensibility than for visual acuity.
D 2
30
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
APPENDIX XI.
ExTRACT from Prof. SNELLEN's Bow MAN LECTURE (Trans. Ophth. Soc., XVI-1896).
This extract is given, as being of considerable interest historically —
Another subject on which these observations may
throw light is the question, “What intensity of light
“is required for trades in which a good visual acuity is
“essential P "
We were led to start these observations by a
question to this effect addressed to us by our Govern-
ment. In obedience to Art. 6 of the law of 20th June
1895 on factories, regulations were wanted for the
required illumination of factories and workshops, and
the question submitted to us was: “Is it possible to
“ determine the maximum amount of light necessary
“ to the workman with normal eyes for a certain sort
“ of work P And, further, if such an amount of light
“ is to be determined, is there a practical method to
“ measure that amount P”
To answer these questions we set to work in a
practical way, and repaired with the photometer to
workshops, in order to determine the intensity of day-
light at different times, and, further, when twilight
begins to fall, to ascertain where at the waning of
daylight the want of light begins to impede the man's
work. In a printing business we found this to be the
case for compositors when the illumination sinks below
15 m.c. With an intensity of 15 m.c. a visual acuity
of 6/6 is the extreme limit. As a rule, all work is
arranged so that it can be done at this vision. But
for the man to have his whole visual acuity at his
disposal, it is necessary that in the long run a much
gréater intensity of light should be afforded.
If, however, the intensity of light at dusk is not to
fall below 15 m.c., we shall be sure to have in the
daytime an intensity of between 30 and 50 m.c. In
answer to the questions which were laid before us, we
came to the following conclusions —
“That in every workshop a minimum amount of
15 m.c. is necessary for work resembling reading,
whereas a minimum of 10 m.c. will do for coarser
work, e.g., that of carpenters and blacksmiths; that in
broad daylight the required amount is between 30 and
50 m.c., and that it must be possible to exclude direct
sunlight. The determination of the intensity can be
done best by means of a Weber's photometer.”
APPENDIX XII.
SUMMARY OF REPLIES FROM OPHTHALMOLOGISTS AND OPHTHALMIG SURGEONs To QUESTIONS
- BY F. RICHARDSON CROSS, F.R.C.S. .
I sent the questions reproduced below to about 300
oculists or medical men interested in the subject, with
a request for information, and the replies handed to
the Committee and Summarised below were those
which seemed likely to be of service to the Committee,
or which suggested that trouble, or even slight ailments
of the eyes, might sometimes be caused by insufficient
or imperfect lighting. The very large majority of
answers (about nine-tenths of the whole 300) indicated
that the writers had no knowledge of mischief to the
eyes as being directly due to defects in lighting.
evidence is therefore negative as regards any definite
damage to the eyes being caused by faulty lighting;
at the same time, it is obvious that good lighting is
more comfortable to the worker, and would be likely
to materially improve his output.
QUESTION 1-Have you any statistics or opinions.
which will give information as to the prevalence
of eye trouble, slight or serious, occurring in, or
depending on, any trades of which you have
special knowledge &
RAYNER BATTEN, M.D., London.
Has not given any special attention to the question,
as the district served by the Western Ophthalmic
Hospital has few factories or workshops. Has com-
plaints from dressmakers and clerks and others com-
plaining of defective light, but it has been found
in most cases the cause of trouble is errors of
refraction.
W. ERNEST THOMSON, M.D., Glasgow.
Has many complaints of electric light as cause of
eye trouble, but in the end refraction error is often
found to be the whole cause of the trouble. -
A. S. CobbLEDICK, M.D., London.
Sees many clerks who work all day by electric
light, and who complain particularly of metallic fila-
ment lamps. Is of opinion that this light brings out a
refractive error very quickly. Correcting glasses only
The
strain on the eyes.
partly relieve them of discomfort. Has not seen any
serious trouble from this cause.
THOMAS H. BICKERTON, M.R.C.S., L.R.C.P. Ed.,
Liverpool.
During 30 years’ practice has not met cases where
trouble is ascribed to insufficient or unsatisfactory
lighting of factories and workshops. Insufficient
lighting of offices and schools merely reveal refractive
€1. I'Ors.
W. B. INGLIS PoſLoCK, M.D., Glasgow.
Has cases of postal sorters who complain of the
lights in the sorting hall. He has found congestion
of the optic nerve due to light shining directly on the
man's eyes.
A. STANLEY PERCIVAL, M.A., M.B., Newcastle.
The only ailment he has found due to insufficient
lighting is coal miner's nystagmus. . He regards this
as due to some inherent nervous instability which
shows itself in nystagmus after working in strained
positions. Regards insufficient lighting as a con-
trolling and aggravating cause, as it entails greater
In One case a chronic conjunc-
tivitis seemed due to electric light. It ceased on using
an oil lamp.
H. S. Elworthy, F.R.C.S., Ebbw Vale, Mon.
Has no statistics of eyesight trouble occurring in
factories and workshops. Gives much information
regarding miners' nystagmus in relation to the illumi-
nation conditions in mines.
RANSON PICKARD, M.D., F.R.C.S., Exeter.
Has refraction cases at the eye infirmary from :—
(1) Lace veil mending shops.
(2) Honiton lace workers (nearly all work at,
home).
APPENDICES.
31
In neither (1) nor (2) are these errors caused by the
work, but are revealed by it. Myopia is sometimes
increased by it.
EDGAR STEVENSON, M.D., Barrow-in-Furness.
Has dealt with thousands of accidents in shipyards,
but the work is mostly carried on in daylight, and the
only cases he mentions are from damage by electric
welding to spectators who look on without proper
protection of the eyes. The workers’ eyes are pro-
tected by glasses and do not suffer.
A. MATLAND RAMsay, M.D., Glasgow.
Experience has been mainly with miners and steel
workers. Mentions nystagmus as likely to be less
frequent under improved lighting, and cataract as
occurring in iron and steel workers, though he does
not consider their work as the obvious cause of
cataract.
W. BEAUMONT, M.R.C.S., Bath.
Experience with workers in the following trades —
Coal mining–Nystagmus cases not common.
Cloth Factories—No evidence that the workers
Suffer in consequence of insufficient or unsatis-
factory lighting. :
Stay and Glove Factories—No complaints and
no excess of disease.
Railway Works—Employees do not suffer from
eye disease abnormally.
Stone Mines—-Traumatic cases are not common.
Conjunctivitis is exceptional.
Schools—The large number of children wearing
glasses is due to hypermetropia and hyper-
metropic astigmatism.
ERNEST H. CARTWRIGHT, M.D., Ticehurst, Sussex.
Has no cases regarding factory and workshop
lighting. Gives his personal experience and opinion
upon private house lighting.
BERNARD CRIDLAND, F.R.C.S.Ed., Wolverhampton.
Confines his remarks to details regarding glass-
blowers' cataract, cataract in puddlers, the effects of
tin Smelting, and similar gross cases of irritation.
ALLAN RUTHERFORD, M.B., Barrow-in-Furness.
Deals almost exclusively with gross cases of irrita-
tion such as Siemens and Bessemer steel making and
other processes. Has never met a case asking for
“compensation' due to any eye disease from light or
glare in the works.
PHILIP A. HARRY, M.D., Rochdale.
Experience is mainly with textile workers, of whom
the majority of the patients are weavers, who complain
of frontal and occipital headache. States that weaving
is very trying with artifical light and that there is
mo precaution against glare which is not excessive.
J. WALTON BROWNE, M.D., Belfast.
No case of trouble caused by insufficient or unsatis-
factory lighting have come to his notice with the
exception of some cases of conjunctival trouble caused
by unprotected electric lights.
GUSTAVUS HARTRIDGE, F.R.C.S., London.
Sees hundreds of cases from the G.W. Railway
Swindon Works. Has no experience of any of the
troubles indicated in the question.
CLEMENTS HAILES, M.D., Clifton, Bristol.
Has no information of diseases or affections arising
from faulty lighting in factories, nor of any complaints
made liable to compensation.
M. STEPHEN MAYOU, F.R.C.S., London.
The major part of his hospital work is in connection
with typists, clerks, and compositors. States that the
latter people are particularly difficult to do anything
for satisfactorily owing to the nature of their work,
which is often very badly illuminated. He deprecates
light sources which are rich in ultra-violet rays, and
is in favour of indirect lighting.
a 30030
J. ARTHUR WooD, M.B., Hereford.
Has no definite information, as most of the operatives
in his district work by daylight. Expresses the
opinion that bright sources of light are serious factors
in the question, but has never comes across a case
where conjunctival irritation could be ascribed to
them.
Gives an extract from Behr's article in the Archives
of Ophthalmology, 1913, demonstrating chronic injury .
of the eye by artificial light in four cases, showing
itself in impairment of the adaptation to dark
without objective trouble. There is always con-
siderable disturbance of the adaptation to dark in
aphakic eyes, and he attributes it to the intense action
of the ultra-violet rays.
T. HARRISON BUTLER, M.D., Coventry and Leamington.
Has seen no eye trouble which can be fairly ascribed
to defective illumination of workshops, but has a lot of
miners’ nystagmus.
CHAs. H. B. S.HEARs, L.R.C.P., M.R.C.S., Liverpool.
Has little experience with factory workers and does
not recollect any complaints about the illumination of
workshops.
JoHN Rol,STON, L.R.C.P., M.R.C.S., Plymouth.
Cannot recall any instance of trouble to be
ascribed to insufficient illumination or unsatisfactory
lighting.
ROBERT JACQUES, F.R.C.S., Plymouth.
Has not had experience with factories, and ex-
presses the opinion that there should not be a large
contrast of shade with illumination in the same room.
Light should be steady, well diffused and shaded
from the eyes. He gives no instances of trouble arising
from bad lighting, -
E. E. MADDOX, M.D., F.R.C.S.Ed., Bournemouth.
Has no experience with factory or workshops'
lighting.
QUESTION 2.—Is any particular protection of the
eyes advisable in any of these ?
A. S. CoBBLEDICK, M.D., London.
The position of the light is not enough considered
and its proper arrangement is very difficult where
many clerks are working in One room.
W. B. INGLIS Pollock, M.D., Glasgow.
Shaded lights required for each worker.
H. S. ELWORTHY, F.R.C.S., Ebbw Vale, Mon.
Protection for miners is needed from looking at
maked lights when going to and from work,
RANson PICKARD, M.D., F.R.C.S., Exeter.
No particular protection
correction for refraction.
EDGAR STEVENSON, M.D., Barrow-in-Furness.
required other than
Protection by special goggles in electric welding
and ship-repairing work.
BERNARD CRIDLAND, F.R.C.S.Ed., Wolverhampton.
Deals with protection for glass blowers and similar
workers.
GUSTAvus HARTRIDGE, F.R.C.S., Tuondon.
Is strongly of opinion that spectacles (wire or
crystal) should be worn for protection of the eyes in
engineering and similar works, against flying particles.
T. HARRISON BUTLER, M.D., Coventry and Leamington.
Deals with protection against flying particles.
JoHN RolsTON, L.R.C.P., M.R.C.S., Plymouth.
Mentions cases of damage to sight, when men have
failed to use protective glasses provided when working
with arc lights (searchlights),
ROBERT JACQUES, F.R.C.S., Plymouth.
Bxpresses the opinion that light should be directed
to the object observed but shaded from the eyes.
D 3
32
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
E. E. MADDox, M.D., F.R.C.S.Ed., Bournemouth.
Compositors, who are apt to have gas lights before
their eyes only a foot or two away, should have them
screened with small metal plates fixed to the burner
and reflecting the light on the work.
W. BEAUMONT, M.R.C.S., Bath.
“Protectors are only useful to prevent traumatism.
Shades and tinted glasses, except in cases where the
work is highly coloured or iridescent, are not advisable,
because it is beginning at the wrong end.”
J. ELLIOT SQUARE, F.R.C.S., Plymouth.
No comments.
QUESTION 3.−What arrangements for proper or
artificial lighting are made in the workshops,
and how would the illumination be prac-
tically improved in any special trades to the
best general advantage of the workmen 2
A. S. CoBBLEDICK, M.D., London.
Expresses the opinion that a large central shaded
light close to the ceiling, or several screened lights
with reflectors near the ceiling, would greatly assist.
F. W. EDRIDGE-GREEN M.D., F.R.C.S., London.
The retinal stimulus is a liquid photograph sur-
rounding the cones. Anything which would interfere
with a good photograph interferes with vision. En-
closed is a note of the “Theory of vision,” also given
in evidence.
J. WALTON BROWNE, M., D., Belfast.
Where electric lighting is used the lamps should
be covered by a shade to throw the light on the work.
GUSTAVUS HARTRIDGE, F.R.C.S., London.
Regards top day-lighting the best, and for artifieial
light a number of low-power lamps better than a few
lamps of very high power.
CLEMENTS HAILEs, M.D., Clifton, Bristol.
Explains north-lighted roofs, and states that all
glass admits too much heat. Bottling cellars are the
worst in his district with ordinary gas jets or with weak
and not diffused electric light.
M. Stºries MAYoU, F.R.C.S., London.
Considers the best lighting is that reflected from a
white ceiling.
T. HARRISONIBUTLER, M.D., Coventry and Leamington.
Most of the shops in Coventry are well lighted by
glazed roofs and electric light. .."
ROBERT JACQUES, F.R.C.S., Plymouth.
Thinks it is often overlooked that while the work is
brightly illuminated, the rest of the room is all dark.
Thinks the contrast leads to discomfort, which can be
avoided by having the rest of the room moderately
illuminated. ‘.
E. E. MADDox, M.D., F.R.C.S.Ed., Bournemouth.
Almost everything in a workshop should be
whitened and the lighting should be partly direct on
special work and partly indirect, the source of light
being shaded from the workers’ eyes. The floor and
benches should not be whitened, nor, if all the workers
face in one direction, should the wall facing them be
too white.
W. BEAUMONT, M.R.C.S., Bath.
Toes not think enough use is made of the contrast
of black and white. It is used in books, black types
and white papers, but it should be carried further
The carpenter should have a black bench and the lace
maker a black pillow, &c.
QUESTION 4.—What kind of artificial illuminant is
in your opinion the most satisfactory, and
how is it to be best arranged so as to avoid
either shadow or glare 2
All answers deal practically with various applica-
tions of electric lighting.
W. B. INGLIS POLLOCK, M.D., Glasgow.
Electric lighting reflected from the ceiling.
F. W. EDRIDGE-GREEN, M.D., F.R.C.S., London.
The lighting should be uniform and strong con-
trast avoided. A bright light which can catch the eye
is particularly to be avoided. The artificial illuminant .
which has the nearest composition to average daylight
is the best.
IH. S. ELWORTHY, F.R.C.S., Ebbw Vale, Mon.
Lays stress on :-
(1) Character of light. - -
(2) Reflecting surface on which light falls.
(3) Light should be diffused rather than direct.
Under (1), red and yellow lights more luminous
than blue, and less exhausting to the visual purple.
EDGAR STEVENSON, M.D., Barrow-in-Furness.
The are lights used in engineering shops seem to be
Satisfactory. The men working in boilers and tunnels
use candles.
J. WALTON BRowNE, M.D., Belfast.
Prefers electric light if well covered by a shade. If
the lights are not covered by a shade, which seems
impossible in some places of business, it is difficult to
avoid shadow and glare. Explains the arrangement
which he advised in the instrument room of Post
Offices, consisting of a standard carrying electric lamps
with green shades, one lamp for each instrument, a
shade being placed at the level of the operator's fore-
head. Formerly where the instrument rooms were
illuminated by pendants from the ceilings, there
were many complaints of shadow and glare. Arc
lamps high above the floor give good general diffuse
illumination.
CLEMENTS HAILES, M.D., Bristol.
Prefers electric lamp with diffusing bowl below.
C. G. R.Uss WooD, F.R.C.S., Shrewsbury
Metallic filament electric lamps cause more glare
than carbon filaments. Prefers holophane covers for
avoiding this trouble.
T. HARRISON BUTLER, M.D., Coventry and Leamington. -
Has found mercury vapour lamps in the roof supple-
mented by movable incandescent lamps with top shades
satisfactory. The mercury lamp must not be placed
near the work on account of ultra-violet rays, which
would cause “Ophthalmia electrica.”
W. BEAUMONT, M.R.C.S., Bath.
If sunlight is impossible, then prefers electric light,
at the Zenith, sufficiently strong to give a good light on
the work.
J. ELLIOT SQUARE, F.R.C.S., Plymouth.
Prefers electric light placed about eight feet from
the ground, the shade being of ground glass. It should
be above and to the left of the writer, above and behind
the reader.
APPENDICES, - . . . . 33
APPENDIX XIII.
CIRCULAR LETTER, ADDRESSED TO CERTAIN OPERATIVE ASSOCIATIONS CONCERNED witH FINE WoRK.
The following letter was addressed to five Operative
Associations concerned with trades in which the nature
of the work might involve injury to eyesight.
Home Office,
London, S.W.,
DEAR SIRs, 5th January 1914.
IN reference to the evidence you were good
enough to give before our Committee recently, we are
directed to inquire whether you could furnish our
Committee with the necessary information to enable
them to trace amongst the members of your Associa-
tion, or elsewhere any specific cases of injury to
eyesight caused by working with insufficient light or
with a badly arranged system of lighting.
Yours faithfully,
D. R. WILSON,
C. C. PATERSON,
Joint Secretaries.
The replies received are appended :-
Amalgamated Weavers’ Association,
Ewbank Chambers,
Accrington,
DEAR SIRs, 9th January 1914.
I HAVE received your letter and read the same
to my executive to-day. They are not prepared with
specific cases of bad eyesight caused by bad lighting or
illumination amongst weavers, but they desire to point
out that bad eyesight would certainly follow in any
case where workpeople had a strain on their eyesight
through the fault of bad lighting. To their mind it is
Very evident that such would be the case, because at
various times complaints have been made by weavers
at certain mills of having to follow their work under
great difficulty on account of the bad lighting.
Yours faithfully,
JOS. CRoss.
The Joint Secretaries,
Committee on Factory Lighting.
Association of Beamers, Twisters,
Drawers, and Machine Workers,
Heywood,
DEAR SIRs, 10th January 1914.
I COULD not say that there are any cases T could
put my hands on, but I will write to each of our
districts and get from our secretaries any information
I can.
Yours truly,
W. C. ROBINSON.
The Joint Secretaries,
Committee on Factory Lighting.
Amalgamated Society of Operative
Lace Makers,
Pembridge Place,
Mount Street,
Nottingham,
6th January 1914.
IT would be a very difficult matter to give you
a specific case of injury to eyesight caused by insuffi-
cient lighting, as for instance, take the case of two men
working the same machine and under exactly the same
conditions, one may require glasses at a very early age,
where the other one may dispense with glasses up to
quite an old age.
DEAR SIRs,
A large percentage of our superannuated members
have quite good eyesight, and it may be contended
that in their days the artificial light would not be so
good as at present, that may be so, but in those days
they would have at least two lights to machines which
were but 2 or 3 yards wide, the very widest being 4 yards
wide, while we are working machines to-day 5 or 6 yards
wide with but two lights. Then again the modern
machine is speeded up to nearly double the number of
motions per minute to what obtained in the old days.
I am afraid I have gone away a little from your
query.
Yours respectfully,
C. WARDLE.
The Joint Secretaries,
Committee on Factory Lighting
Jewish Tailors’ and Tailoresses’
Trade Union,
London,
DEAR SIRs, 22nd January 1914.
I SHALL be pleased to give you specific cases of
injury to eyesight caused by insufficient lighting in
workshops, if you will give me a date when and where
to produce them.*
Yours very sincerely,
A. HILLMAN.
The Joint Secretaries, -
Committee on Factory Lighting.
* See Minutes of Evidence, qq. 3070–3116.
APPENDIX XIV.
EXPERIMENTAI, Room AT THE NATIONAL PHYSICAL LABORATORY.
The experimental room installed for the Committee
at the National Physical Laboratory was equipped
with different methods of lighting and so arranged
that the illumination by each method could be readily
varied in degree. Various phenomena brought to the
notice of the Committee by witnesses were examined
in this room;’ workpeople were tested to ascertain the
illumination required for their work, and the Members
of the Committee made experiments under conditions
of illumination similar to those existing in the various
factories which were inspected by them.
1. DESCRIPTION OF ROOM.
The room was rectangular in plan, 24 feet long by
12% feet wide, the height from floor to ceiling being
10 feet 4 inches. The whole of the wall surface, as
well as the ceiling, was whitened in order to reproduce
the conditions obtaining in a small factory room. At
the same time black curtains were provided which
could be drawn across the white walls, thus approxi-
mating to the conditions in the centre of a large
factory room where the effect of the light reflected
from white walls is negligible.
In addition to this the room could be partitioned
into three compartments by means of white or black
curtains, each compartment being illuminated with its
own lamps. In this way an observer could pass
quickly from one set of previously arranged lighting
conditions to another. Comparisons under these con-
ditions were thus made possible without the necessity
of intermediate adjustment. *
D 4
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND worksHOPS:
PLAN AND ELEVATION OF ExPERIMENTAL Room AT THE NATIONAL PHYSICAL LABORATORY.
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ELFVATION
The following three systems of illumination were
installed :-
(1) Direct lighting by unobscured metal filament
lamps with Ordinary opal glass shades. The
height of the centre of these lamps above the
floor was 7 feet 6 inches.
(2) Indirect lighting by metal filament lamps with
inverted white reflectors which intercepted all
downward light and reflected it upwards upon
the ceiling, whence it was diffused over the room.
The height of these lamps was the same as those
of system (1). •º
(3) Shielded lighting in which similar lamps to
those used in system (1) were enclosed in alu-
minium shades of approximately parabolic form.
These shades shielded the eyes from the direct
light of the lamp, throwing it in a downward
direction upon the table beneath. The height of
these lamps could be varied at will.
By means of resistances placed in circuit with the
larmps, any degree of illumination up to the maximum
of approximately 12 foot-candles (underneath the
lamps) could be readily obtained. To obviate the
difficulty arising from the difference in colour of the
light when the lamps were running at very low voltages,
it was possible to replace the ordinarily used lamps by
others of smaller candle-power.
Electric light was used in the equipment of this
room. On account of the greater ease of regulation for
experimental laboratory purposes. So long as a suitable
and conveniently adjustable means of lighting was
available it was not of consequence for the purpose of
the experiments whether it was from gas or electric
lamps. -
In the case of the indirect lighting the illumination
did not vary seriously over the area below the lamps,
but with the direct lighting the illumination midway
between the lamps was 70 per cent. of that immediately
underneath them.
The uniformity of illumination from the shielded
lights was more dependent than in the case of the
others on their height above the table, but this system
was used mainly for the examination of the effects of
local lighting. -
It was found that the reduction in the illumination
at the centre of the room, due to blackening of the
walls, was approximately 25 per cent. in the case of
direct lighting, 7 per cent. for indirect lighting, and
negligible for the shielded lights.
2. EXPERIMENTS WITH WORKPEOPLE.
The principal workpeople examined were seamstresses
from the workrooms of Some of the principal London out-
fitting firms. They were examined two at a time, each
examination lasting for about a day. In addition to
these, two tailors from the East End of London have
been examined, but the results obtained require supple-
menting and confirming before they can be considered
reliable. In the case, however, of the seamstresses,
three entirely independent examinations were made,
and the measure of agreement which the results afford
indicates that they may be accepted as of fairly general
application for the type of work upon which they were
engaged.
The workpeople were asked to work on various
materials mostly without any pattern, with cotton of
the same colour as the material. Chief attention was
paid to white and black cloths, as representing the
two extremes. For work on any given material the
illumination to start with was put at a value which the
workers stated was too low for the work in question.
It was then raised by a definite amount and the two
workers under examination were left to sew for 15 or
20 minutes, after which they were asked whether in
their opinion the illumination was sufficient for the
work they were doing. If it was not sufficient a furthel
increase was made and they were left to work for a
further period. In this way an illumination was
reached which the workers considered sufficient for
the work in question. With the lighter materials
this point was in all cases quite definite, but when
working with black cloth, although the workers
stated that, for instance, 4 foot-candles was sufficient
by which to see their work, they all considered that it
was not really a high enough illumination for comfort.
The illumination for comfortable working with black
cloth proved on the average to be about 5% foot-
APPENDICES. 35
candles. Similar tests were made with each pair of
workers, and the following table gives the decisions
arrived at by each one of them together with data as
to the coefficient of reflection of the materials worked
upon.
Illumination required by Seamstresses for working on
different self-coloured materials with threads to
match material. -
Coefficient tºº, º
Material. of Worker. mºtion § ind
Iteflecti for continuous which may be
eflection. work considered as
tº ample.
Per Foot- Foot-
cent. candles. candles.
White 97 Miss S. # !
calico. Miss W. #
Miss O. }
Miss F. #
Miss B. #
Miss L. #
FIolland 52 Miss S. }
colour. Miss W. #
Miss O. #
Miss F. #
Miss B. #
Miss Tu. 1}
Slate 12 Miss S. 2
colour. Miss W. 2
Miss O. 1}
Miss F. 1}
Miss B. 1;
Miss L. 1%
Purple, 8 Miss S. 2
with Miss W. 2
Strongly- Miss O. 2}
marked Miss E'. 2
sheen. Miss B. 2
Miss L. 2
Black 2 - 4 Miss S. 4. 5;
Miss W. 4 5%
Miss O. 4. 5
Miss F. 4. 5
Miss B. 4 5–6
Miss L. 4. 5–6
Black *- Miss S. 4
velvet. Miss W. 4.
Miss O. 5
Miss F. 5
Em- 11 Miss B. 2 3
broidery. Miss L. 2 3
All the above results were obtained with “direct
light,” that is to say, the light was received directly
from a lamp placed above the worker in such a way as
to be free from glare. Many tests were also made
with the object of ascertaining the relative ease with
which sewing work could be carried out with “direct ’’
and “indirect ’’ light respectively. When, for any
given material worked upon the value of “direct .
illumination had been decided on which was regarded
by the workers as adequate, the lighting was quickly
switched over to the “indirect ’’ type of equal intensity.
The decided opinion of the workers in every case was
that the “indirect ’’ illumination, even though it might
be equal in intensity to the “direct” illumination, was
inadequate, and required to be very appreciably in-
creased for sewing work. The increase asked for was
in one case 100 per cent. and in others about 40 per
cent. The reason for this was investigated separately
and is dealt with later (page 37). -
The sight of each seamstress was examined for
errors requiring correction with glasses. Several of
the workers proved to have imperfect sight, but did
not appear to show any desire for a higher illumination
by which to work than those with normal sight. Trials
were also made with blackened instead of whitened
walls, but provided the illumination on the work was
arranged to be the same in both cases the workers did
not find that their ability to carry on work was
affected.*
3. OBSERVATIONS BY THE COMMITTEE IN THE
ExPERIMENTAL ROOM.
(a) Degrees of Illumination.—The illumination in
the room was adjusted to different values from 0 - 1 foot-
candles to 10 foot-candles, and at each illumination the
members of the Committee tested their ability to
distinguish detail by means of cards with figures
printed on them in ordinary type varying from a height
of 1 2 mm. to 2 8 mm. The cards were of different
colours from white to dark blue, so that the contrast
between the black figures and coloured cards varied
appreciably. - -
The observations were made with (a) thoroughly
diffused light (indirect), (b) direct light from exposed
sources, (c) direct light from well-shaded sources.
It was found that whilst it was possible to read the
smallest type on the white cards at an illumination of
about 0 75 foot-candles, the small figures on the dark
blue cards could not be seen with an illumination of
6 foot-candles. The type of illumination, whether
direct or indirect, made no difference to the ability to
see so long as there was no direct reflection from the
surface of the cards. -
An illumination of from 3 to 4 foot-candles gave
the impression from general observation of a well-
lighted room, whilst it appeared that from 0-1 to 0.25
foot-candles would be the order of illumination which
would suffice for corridors.
(b) White and Black Walls.-The effect was studied of
illumination by direct and indirect light both with and
without the presence of white walls. The increased
restfulness of the diffused (indirect) light was noted,
and also the annoyance through the glare of bare
lights, particularly when these were seen against a
dark background. -
(c) Perception of Detail by Direct and Indirect Light.
—The ability to discern the details in fabrics was tested
both by direct and indirect light, and it was found
that the absence of shadow which resulted from the use
* Report on the eyesight of 6 seamstresses by J. Herbert
Parsons, Esq., M.B., D.Sc., F.R.C.S.
–0' 75 diopter sph: :
+2'25 diopter cyl.-> in the
R. eye, hypermetropic astigmatism, -ī- 1 diopter cyl:— in the
left.
Miss S. has mixed astigmatism
Her vision is—
- & rºº º f f ... 6
R. à J aeger 1, with difficulty, at 6"; with correction 9'
L. * Jaeger 1 at 6" more easily; with correction . Eyes
otherwise normal.
Miss W. is quite emmetropic—normal in every way—º each
eye.
Miss O. is practically normal—trace of hypermetropia.
Miss F. has a lot of astigmatism—
6 .., , – 0° 5 sph. 6
R. 15 J. 1, with-Hä.1 : 5 cyl. J. F 6.
6 5 1. l J. ..] : ſº , , , – 0 5 6
L. 36 J. 1. with difficulty — with – 1 - 5 -, * 9.
Miss B.- t
R.W. = . no manifest hypermetropia, reads J. 1. easily.
L.W. = } ditto ditto ditto
Miss L.-
Fundi normal. Emmetropic
6 6
R.V. = i, J. I. L.V. = g J. 1
Fundi normal.
6
R.W. with – 0 5 diopter cyl.Sa 20° down and in -.'
L.V. with – 0.5 diopter cyl. 20° down and in T
º
36 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
of indirect light seriously impaired the ability to see in
detail the separate threads in a self-coloured cloth.
(See also p. 37 of this Appendix.)
(d) Diversity Factor.—A long work bench was illumi-
nated by direct light from three sources, and in such
a way that the illumination at the ends was one-seventh
of that in the centre. To ordinary observation, unaided
by measurements, the actual difference of illumination
appeared to be much less than this. -
(e) Glare.—A test card, having figures printed on it,
was fixed at eye height and an observer adjusted his
distance from it so that he could just read the lines
of figures. The time taken by him to read the lines
of figures was noted, after which a 100 candle-power
lamp was placed in front of him, so that the vertical
distance between the lamp and test card subtended
an angle of about 20° at his eye. The time required
to read through the figures under these conditions of
glare was again noted.
ensure that the illumination on the card was the same
in the two series of readings. At illuminations from
2 to 4 foot-candles there was no diminution of ability
to read the figures, but with an illumination of 0.5 foot-
candle the exposed source of light renderedit practically
impossible to distinguish them.
(f) Ability to see Detail in different Materials of the
same Surface Brightness.-Blue fabrics of identical
texture but varying from very light to very dark blue”
were examined under conditions of illumination such
that the surface brightness of all the fabrics was the
same. That is to say:—
the coefficient of reflection X illumination = constant.
In the opinion of the Committee when the above
relation held, the ability to distinguish detail in all the
fabrics was the same ; the matter, however, required
further investigation.
This question was subsequently further investigated
by Mr. W. C. D. Whetham, F.R.S., a member of the
Committee, who reports as follows:–
It is a matter of common knowledge confirmed
conclusively by evidence given to the Committee by
operatives, that more light is required in factories
where the colour of the material worked upon is dark
than where it is light. This fact would make all
attempts to define “ adequate illumination " almost
hopeless unless some new criterion can be discovered.
Dark coloured substances look dark because they
reflect much less light to the eye than light coloured
substances, and it seemed possible that the power of
distinguishing detail, on which comfort and quality
depend, would be related to the actual amount of light
which entered the eye, that is, to the surface brightness
of the material, rather than to the amount of light
falling on the work, that is the illumination.
To examine this question, an investigation was
carried out at the National Physical Laboratory with
the skilful help of Mr. Bernard P. Dudding, the
arrangements being previously made under the superin-
tendence of Mr. C. C. Paterson. The work was carried
out in a dark room in which the illumination given by
electric light was under control. - -
In the first series of experiments, four Samples of
calico were used. They were dyed different tints of
blue ranging from very light to very dark, almost black.
The illumination was slowly raised by an assistant
till the observer, who was ignorant of the illumination
reached, was able to distinguish the threads of the
warp and weft of the calico. -
The illumination was then kept steady and measure-
ments taken of the illumination and of the surface
brightness of the material relative to the surface
brightness of the white card of the lumeter. The
following results were obtained:—
* The approximate coefficients of diffused reflection of the
three principal fabrics examined (expressed as a percentage
of incident light which was diffusely reflected), were as
follows : —
Dark blue * - 6 per cent.
Medium blue - - 14 per cent.
Light blue mº - 40 per cent.
Precautions were taken to
OBSERVER W.C.D.W.
Corresponding surface
brightness.
Tliumination needed to make
the threads visible.
I. Very light blue calico.
Foot candles.
1' 4 * -> - - - O - 7
I 65 - - - - - 0 - 9
1 - 4 wº tº- - - - 0.7
II. Light blue calico.
Foot-candles.
2 - 0 - - - - - () . 75
1.7 * - -- - - 0 - 70
III. Full blue calico.
4 8 - º º * - 0 63
5 : S - - - - - 0 '86
IV. Dark blue calico.
12 - 0 tº - - - - 0 62
12 - 5 - - * - - 0 - 68
OBSERVER B.P.D.
I. Very light blue calico.
1:0 - - - - - 0.64
0.8 t- - - - - 0 - 52
II. Light blue calico.
1 - 9 - - * - - () . 72
1. 3 - - - - - 0 - 50
III. Full blue calico.
4 - 0 - - - - - 0 - 52
3 : 6 - - - º - O - 48
IV. Dark blue calico.
10 - 5 - - º - - 0. 60
14 - 0 - - - - - O - 85
Hence it appears :—
(1) That the illumination needed to make work
possible on a very dark material may be 10
times that required with a very light material.
(2) That, on the other hand, the requisite surface
brightness is constant within the limits of
experimental error.
(3) That the average surface brightness needed
to make the threads of calico of different tints
visible to one normal eye (W.C.D.W.) may be
represented by 0 73, and to another normal
eye (B.P.D.) by 0.60.
Another series of experiments were made with
coloured cards on which rows of figures were printed.
Here the visibility depends on the contrast of colour
between the coloured card and the black ink. The
problem is therefore different from that of the ade-
quate illumination of calico where the visibility
depends on the shadow cast by the threads.
OBSERVER W.C.D.W.
Illumination needed to make Corresponding surface
print legible. brightness.
0.144 - white card - 0:13
0 - 125 - pink card - 0 - 11
0 - 50 - light blue card - 0:19
0 - 80 - dark blue card - 0 - 20
OBSERVER B.P.D.
() - 04. - white card - 0.044
0 - 05 - pink card - 0° 044
0 - 104 light blue card - 0.048
0 - 20 - dark blue card - 0° 052
In this case, while the illumination needed to make
print legible on a dark blue card is some five times that
required with a white card, the surface brightness is
nearly constant, though there are some indications
that it tends slightly to increase with the darker
colours. This is natural, as with a black card, black
print would be presumably invisible at all illumina-
tions. But, except in this extreme case, there seems
APPENDIGES. 37
reason to believe from experiments that, for a given
kind of work, it may be found that the necessary sur-
face brightness is independent of the colour of the
material.
4. PERCEPTION OF DETAIL BY DIRECT AND
INDIRECT TIGHT.
The degree of illumination required for the purpose
of distinguishing detail under different systems of
illumination was the subject of further experiment.
The investigations described above were repeated by
other observers, and the conclusions before arrived at
were confirmed, viz., that the threads of different-
coloured materials could be just distinguished when the
illumination was raised to such a value that the surface
brightnesses of the different materials were the same.
In order further to amplify these experiments under
more rigid conditions an investigation was carried out
at the National Physical Laboratory by Mr. J. W. T.
Walsh, using embossed matt papers of different shades
of grey, but all non-selective in their diffusion pro-
perties. Ten different specimens of toned paper were
used, varying in shade from very dark to very light
grey. They were embossed from a copper plate having
an arbitrary design which included lines of many
different depths, the embossing being carefully per-
formed in a hand press, so that the mattness of the
surface of the papers was as far as possible unaffected.
These papers were then illuminated from a single
and relatively small source of light and viewed from a
fixed distance and in a definite direction.
It will be observed that the visibility of the
embossed pattern depends (1) on the variation of the
surface brightness over the raised portions of the
pattern, due to changes in the angle which such
surfaces make with the direction from which the light
comes, (2) on the shadows cast on the background by
the raised portions of the pattern. Both of these
effects depend upon whether the light comes from one
single direction, or from a number of widely different
directions.
The illumination was gradually raised until one
particular part of the embossed design, which was of
medium fineness, could be just discerned while another
finer portion could not. In this way it was found
possible to obtain results which were reproducible to a
considerable degree of accuracy.
The results obtained are given in the following
table :-
^-
Table.
Approximate | Surface Brightness
Paper No. Coefficient of at point of
Reflection. Visibility of Design.
Per Cent. | Foot-Candles.
1. 80 0 - 031
2 60 0 - 0.29
3 37 0 - 030
4. 23 - () - 0.27
5 21 0 - 031
6 17 0 033
7 16 | 0 - 028
Approximate Surface Brightness
Paper No. Coefficient of at point of
Reflection. Visibility of Design.
Per Cent. Foot-Candles.
9 11 0 - 027
10 9% 0 - 032
11 3# 0 - 0.27
The figures in the last column-show the remarkable
constancy of the surface brightness required for the
perception of detail by direct light, where such percep-
tion mainly depends on the contrast between the
brightness of the ground surface and that of the
shadows cast by the embossed detail or on the variation
of brightness over the surface of such detail.
In the case of indirect lighting no sueh definite
conclusions could be arrived at, but it was readily
apparent that for equal ease in distinguishing detail a
considerably greater illumination was required than in
the case of direct light. This is only to be expected,
having regard to the fact that the shadows shown by
indirect light are always far less intense than those
given by direct light, and that the variation of illumina-
tion over a curved surface is also much less with
diffused light. The superiority of direct light for
sewing was insisted on by the seamstresses who worked
in the experimental room under different illumination
conditions (see page 35).
Some of the main conclusions arrived at as the
results of experiments made at the National Physical
Laboratory may be summarised as follows:—
(1) The illumination required for the perception of
detail in materials having a low coefficient
of reflection is greater than for those which
reflect more strongly, and other things being
equal is inversely proportional to such co-
efficient of reflection; that is to say, for
equal visibility there must be constant
surface brightness.
(2) The visibility of detail in self-toned portions of
fabrics, embossed paper, and similar sub-
stances, depends on the unidirectional
character of the light illuminating them. It
follows and has been shown experimentally
that the ability to distinguish detail in such
substances is for the same illumination much
greater by direct than by indirect light.
(3) Work such as sewing may be comfortably per-
formed on the darkest materials with an
illumination of 5 to 6 foot-candles (direct
lighting). For white calico 14 foot-candles
was found sufficient, and intermediate shades
were found to lie between these values.
(4) The observations on the phenomena of glare
have not as yet yielded definite numerical
results. They have shown, however, that
the presence of a bright lateral light, although
causing a feeling of annoyance, does not
actually diminish ability to distinguish
detail unless the surface brightness of the
object viewed is relatively low.
38 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
APPENDIX XV.
RECORDS AND SUMMARIES OF ILLUMINATION MEASUREMENTS IN FACTORIES.
INTRODUCTION.
The records of observations given in this Appendix
were obtained in the winter months of 1913–1914 at
the instance of the Committee, in Order to reveal as far
as possible the lighting conditions under which some
of the chief industries of the country are carried on at
the present day. The actual observations were made
by Mr. J. W. T. Walsh, B.Sc., of the National
Physical Laboratory, and Mr. G. F. Sedgwick, H.M.
Inspectors’ Assistant, under the direction of the
Secretaries of the Committee, and the Committee are
much indebted to the two observers for the thorough
way in which they carried out their work.
It is not suggested that these records are exhaustive,
in fact they must not be regarded as giving more than
a very general idea of lighting conditions in certain
representative factories in the Engineering, Textile, and
Clothing industries.
The relatively short period each day during which
factories are working under artificial light affords Only
a limited opportunity for observations after dusk, but
use was made of practically all the available time
during which such observations were possible.
The Committee would have liked to be able to
obtain a mnch larger number of observations, but as
this was not feasible the selection of factories was
made as representative as possible, and the Committee
are of opinion that for the chief industries studied the
average results given in the summaries in this
Appendix would not in most cases have been much
affected had a larger number of observations been
available.
Factories investigated.
In the main this Appendix contains the records of
observations in factories associated with the three
industries mentioned above. They were situated in
or around Tuondon, Glasgow, Belfast, Manchester,
Leeds, Liverpool, Newcastle-on-Tyne, Nottingham,
Sheffield, and Bristol. Time did not permit of
measurements being made in the Birmingham or
Cardiff districts, although it was Orignally intended
that this should be done. This therefore has to be
left for a future report.
A tour of inspection, previous to that during which
the measurements were taken, was made in each
district by one of the Secretaries who selected factories
both well and indifferently lighted. Altogether 54 such
factories were chosen and in making the selection
assistance was given by H.M. Inspectors of Factories
for the different districts, whose local knowledge helped
to assure the choice of representative places.
Many of the factories were too extensive to permit
of the taking of observations in all the rooms, and in
such cases rooms were chosen which were as far as
possible representative of the lighting conditions
throughout the factory. In factories having both new
and old sections the choice of rooms for observation
was divided as evenly as possible between the two.
Selection of Observation Points.
The selection of observation points in each room
was carried out on the same principle, every effort being
made to ensure that they should be representative.
Attention was directed in the main—
(a) to the illumination at floors and gangways.
(b) to the illumination at the point where work
was being carried out.
The measurements were made by placing the white
test card at the observation point and measuring the
illumination.
Where artificial light was in use to supplement the
natural light during daytime the artificial light was
turned off whilst observations were being made.
In the case of measurements in gangways and on
floors the card was placed on the floor at One or two
representative positions, and usually a point was chosen
which would serve equally well for observations by both
natural and artificial light.
Natural and Artificial Light.
The illumination at any point by artificial light is
in ordinary circumstances a fairly constant quantity.
Changes, it is true, are liable to occur owing to
fluctuations of the supply pressure, or to accummu-
lations of dirt, on the lamps and fittings, but in any
well regulated installation, changes due to such causes
are not great, and the recorded observations may be
taken as showing definitely the illumination at the
various points by artificial light.
The matter, however, is otherwise with natural
lighting. By daylight the illumination fluctuates
continuously with the external meteorological conditions,
and in addition to these mere accidental fluctuations
it increases gradually each day from sunrise to midday
and wanes again towards sunset. Further it is not
always appreciated that the illumination in the open
at noon on a clear day in summer is five times greater
than on a similar day in winter. This same difference
between summer and winterillumination will, of course,
find a counterpart inside the workshop, and it will at
Once be seen that no records on isolated occasions of
the illumination in workshops by daylight suffice of
themselves to afford a criterion by which to judge the
lighting. -
Daylight Factor.
The natural illumination in any building must,
however, depend on the amount of light admitted by
the windows, and the efficiency of the window lighting
will be determined by the proportion of the light, inci.
dent on the outside of the buildings, which reaches the
inside of the building. If, therefore, we could obtain a
simultaneous measure of these two quantities we should
secure a criterion for the efficiency of the natural
lighting of the building. It is not practicable, how-
ever, to sum up the total amount of light which a
system of windows admits, and, further, the amounts
admitted will vary at different parts of the building, so
that a general figure for the efficiency of the whole
building would be of little value even if obtainable.
It is possible, however, to obtain a measure of the
lighting efficiency by natural light at any one point in
a building by measuring simultaneously the illumination
at this point and the illumination outside the building.
The latter measurement is, in effect, equivalent to
measuring the illumination at the point inside the
building, but with the roof and walls removed. The
ratio of the inside to the outside measurement ex-
pressed as a percentage is called the “daylight factor *
for that point, and, is a measure of the lighting
efficiency of the building at this particular point. The
daylight factor for roof-lighted buildings such as
weaving sheds is of the order of 2 per cent., i.e., 2 per
cent. of the light which would reach the point if the
walls were removed is actually found there. At the
centre of some workrooms depending entirely on lateral
windows the factor falls as low as 0.01 per cent.,
which means that the light reaching the point in
question is only Toºgoth of that which would reach it
if walls and roof were removed. Within limits a
daylight factor tends to remain a constant quantity
whatever the time of year or the external meteoro-
logical conditions, and the observations by daylight
given in this Appendix have been made with the object
of determining this factor for all the cases considered.
* The suggestion to use such a factor as this as a measure
of the daylight efficiency of a building was first made by
Mr. A. P. Trotter, and has been subsequently developed by
Mr. P. F. Waldram, '.
APPENDICEs.
39
It will be observed that if the daylight factor is
known for any point in a factory we can at once state
what must be the value of the outside illumination
to produce a certain minimum illumination at this
point. If the outside illumination during some of the
winter months does not reach this figure it will be
obvious that the illumination in the factory at the
point in question will be inadequate.
The approximate outside illumination for different
months of the year is discussed in Appendix XVI., and it
will be seen from the figures given there that on an
average day in December the illumination varies
from 500 foot-candles at 10 a.m. to 700 foot-candles at
midday. If the daylight factor at a point in a work-
room does not exceed 0.4 per cent., its illumination
will only reach two foot-candles from about 10 a.m. to
2 p.m., and at other times of the day it will be below
this. Such a room could not be regarded as adequately
lighted in December without additional artificial light,
although in June with an outside illumination at
midday of the order of 4,000 foot-candles the lighting
would probably be satisfactory from 6 a.m. to 6 p.m.
Arrangement of Records.
The complete records of the observations made are
published separately.* A full page is allotted to each
room, and the rooms are grouped according to the
industries and processes carried on in them. For
instance, pages 8 to 19 contain the results of all the
observations in weaving sheds, and pages 112 to 129
those in foundries. Each group of records dealing
with a special industry or process is preceded by a
summary in which an effort has been made to collate
all the results for that industry and present them in
a way which will enable a general survey of the
lighting conditions to be obtained at a glance.
The record sheets themselves contain in the upper
two tables data as to the means of lighting, dimensions
of windows, power and number of lamps, &c., whilst the
lower table gives the values of illumination observed
at the different points and the daylight factors deduced
from them. Underneath is a plan of the room in
question reproduced to scale, with the positions of the
observation points marked in circles on it.
Frequency of 0ccurrence Curves.
The summary for each industry, besides containing
tables which sufficiently explain themselves, has also a
series of curves intended to show graphically to what
extent the various degrees of illumination are in vogue
for floors or gangways, or for any processes connected
with that industry. These curves have been termed
frequency of occurrence curves. Thus taking as an ex-
ample foundry work (Fig. 14, page 57), we have a series
of 114 observations of illumination taken on all the
various foundry floors where measurements were made.
These range from about 0:02 foot-candles to 4: 2 foot-
candles. There may be only one observation as high as
4-2 foot-candles and one as low as 0-2 foot-candles,
the remainder distributing themselves in some way or
other between the extremes. It becomes of importance
to know whether the majority of observations gravitate
towards the higher or the lower limit and what is the
actual mid-point, i.e., the point above and below which
there is an equal number of observations. If a horizontal
scale of illumination be set out and at each illumination
a vertical height be taken proportional to the number
of observations found to lie in the neighbourhood of that
illumination (namely, between certain fixed limits On
either side of it), then the points so plotted will lie on
a curve, any vertical ordinate of which shows, for any
illumination, the frequency with which illuminations
occur in the neighbourhood of that represented by the
ordinate. The two principal features to be noted in
any one of these curves are:— -
(a) The mid-point (explained above).
(b) The general contour and distribution of area
of the curve.
It will be seen that nearly every curve has a .
more or less well defined maximum, which in many
cases occurs at a point very low down on the scale
of illumination. The conclusion, however, must not
* Results of Observations of Illumination in Factories
(Stationery Office Publication). -
be drawn from this circumstance that the majority
of factories have an illumination corresponding to the
point of the curve where the maximum lies. As a
rule, only a small proportion of the total admber will
have this illumination.
The factor which should receive most consideration
is the area embraced by any curve, since this is
directly proportional to the number of observations.
If any given illumination be considered on any curve,
the ratio between the area of the curve which lies
below this illumination to that embraced by the whole
curve is a measure of the relative number of obser-
vations which exist below such illumination. In this
way different sections of any curve may be compared
together with a view to forming a judgment of what
preponderance of factories lies between given limits of
illumination. Conclusions of this nature have been
drawn in the summaries which precede each section of
this Appendix, and they should be considered in con-
junction with the curves to which they refer.
The following is the actual process adopted for
drawing these curves. If, in any series of observations,
the illuminations vary from 0-2 to 4' 0 foot-candles,
limits of plus and minus 0-2 foot-candle would be
worked with. That is to say, the height of the Ordi-
nate at 0-4 foot-candle would be made proportional to
the total number of observations lying between 0 2
and 0.6 foot-candle. At 0-8 the number of obser-
vations between 0° 6 and 1 - 0 would be plotted, whilst
similarly at 1:2 those would be taken which fell
between 1-0 and 1' 4. With a very large number
of observations the points so plotted would lie On
a sufficiently smooth curve, which could be drawn
in without difficulty, but usually the course of the
curve is not well enough defined to permit this to be
done with certainty, and points intermediate between
those plotted are required in order to obtain a smooth
curve. The same process is therefore repeated, taking,
however, illuminations of 0° 6, 1 0, 1' 4, &c., and
working with the same plus and minus limits on these
values. In some cases still further subdivision may
be desirable, but the process of counting every obser-
vation more than Once in this way does not alter a
curve, but merely serves to define it more precisely. The
curves so drawn are dotted in lightly in the diagram
sheets. Some of them are relatively free from irregu-
larities; in others, mainly where few observations
were available, the irregularities are appreciable. It
is presumed that irregularities arise from accidental
causes and would be smoothed out, were a larger
number of observations available. A heavy line curve
is therefore superposed on each dotted One to indicate
the probable course of the smooth curve, and is the
one referred to throughout this Appendix. The hori-
zontal scale of the diagram is, of course, that of illumi-
nation. The vertical scale on the left-hand side has
no special significance and is merely a convenient scale
proportional to the number of observations. The same
scale has been used for all the curves On each diagram,
but may differ in different diagrams. The fact that
the ordinates of one curve in any figure are higher
than those in another diagram of the same figure
merely means that in the first case there were more
observations available.
In some cases the large bulk of the observations lay
below some one value of illumination with a few lying
well above it. In Fig. 12, page 54, for instance,
dealing with engineering shops, although curve A
covers the range from 0 to 10 foot-candles, 8 per
cent. of the observations were above 10 foot-candles,
one being as high as 63. It would have crowded
the lower end of the diagram unduly to contract
the scale so that all points could be plotted, and in
such cases as this an indication is given in the letter-
press of the percentage number of observatious lying
beyond the right-hand end of the diagram and there-
fore not plotted.
An arrow has been placed across each diagram to
indicate its mid-point, this arrow marking the illumi-
nation above and below which there is an equal number
of observations. The position of the arrow may, there-
fore, be regarded as the principal index mark for that
diagram, fixing the centre of distribution of all the
observations with which it deals.
40 DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
FACTORY FI,00RS,
Summary of Daylight Observations.
Measurements were made of the daylight factors
at the floors of most of the factories visited, and,
while it has not been found possible to summarise the
results in a table, an inspection of the values obtained
in factory rooms of different types clearly indicates
the great advantage of a system of roof-lighting, as
against one which depends solely on side windows.
The difference is the more marked as the depth of
the side-lighted room increases, and when there is
obstruction of light by machinery, belting, &c. For
bench work, where operations can be conducted near
the windows, side-lighting may be sufficient, but
where it is necessary for work to be carried on at
other points than those immediately under the win-
dows, roof-lighting is the only system which can be
regarded as yielding satisfactory results. In buildings
of more than one storey roof-lighting is obviously
impossible, and several devices have been noticed for
increasing the light in the interior of such rooms.
Among these, prismatic window glass, and the provision
of a wide central well may be mentioned. The lime-
washing of all walls and ceilings is, of course, a most
important factor for increasing the general illumina-
tion, both daylight and artificial. In several of the
factories visited this fact does not seem to have been
properly appreciated, for the lime-wash, even when
fresh, was in many instances tinted. The whiter the
lime-wash the more effective it will be in this connection.
The cleansing of all windows at frequent intervals is
another necessary provision to which sufficient atten-
tion is apparently not always given. *
FREQUENCY OF OCCURRENCE CURWEs.
Frequency of occurrence curves, embodying the
results of the observations on the floors of all the
factories visited, are given in Figs. 1, 2, and 3. The
factories have been classified according as the chief
system of lighting was –
(a) roof glass;
(b) side windows;
(c) a combination of both roof and side windows.
The following points in connection with these
curves may be noted:—
T. R.OOF-LIGHTING.
The factories included under this heading are those
in which the side glass area does not exceed 25 per cent.
of the roof glass area (in the case of foundries, 20 per
cent.).
2O
IO
O
10
O
2O
| O
O -
o?, 1%. 2% sº. 4%, 5% e?, 7% s% o9, 10%
Daylight Factor (Percentage of Outside
Illumination).
FIG. I.-ROOF-LIGHTED FACTORIES.
A separate curve has been drawn for foundries for
the reason that the windows are very often much
obscured by smoke and dust, and the lowering of the
daylight factor from this cause would, owing to the
comparatively large number of observations in foundries
(approximately 50 per cent. of the whole number taken)
result in an undue lowering of the mid-point daylight
factor for the complete curve.
o
Foundries (Curve A).-The slope to the right is
fairly gradual, indicating a fair proportion of observa-
tions at the higher daylight factors. Six per cent. Of
the observations lie above a daylight factor of 10 per
cent., and so have not been included in the diagram.
All Factories except Foundries (Curve B). —This
curve is rather indefinite in form. It indicates that all
values of daylight factor between 0 5 per cent. and
3 5 per cent. are well represented.
All Factories including Foundries (Curve C).--This
curve necessarily embodies the chief features of the
two preceding ones, having a decided peak at the some-
what lower daylight factor which is prevalent in
foundries, but a gentle slope to the right shows, as
before, a large proportion of observations lying well
above the point at which the maximum of the curve
occurs. Approximately 3 per cent. of the observations
lie above a daylight factor of 10 per cent., and so have
not been included in the diagram. -
II. COMBINED ROOF- AND SIDE-LIGHTING.
The factories included under this heading are those
in which the side glass area is too great for them to be
included under Section I., while the roof glass area is
still effective (i.e., greater than about 2 per cent. of the
floor area).
o9, 193
2%, 2%, 4%, 5% e96 rº,
Daylight Factor (Percentage of Outside
- Illumination).
S.9% 9%. 10%
FIG. 2.—COMBINED ROOF AND SIDE LIGHTING.
Here again, and for the same reason as before,
the observations for foundries have been represented
On a separate curve. It will be noticed that the
mid-points of the curves on this diagram are much
lower than those of the corresponding curves of the
last section, thus clearly indicating the superiority of
a system of lighting which provides as great an area as
possible of roof glass. The chief characteristics of all
three curves (D, E, and F) are the same as in the last
Section.
III. SIDE-LIGHTING ONLY.
None of the foundries visited were lighted entirely
from side windows, and hence only one curve has been
drawn for this section, viz., that for all factories
7 O
6 O
5 O jºid-Point
4 O
3 O
2 O
0.0% 0.5% 1.0% 1.5% 2.0% 2.5% s.0% a.5% ſºož
Daylight Factor (Percentage of Outside
Illumination).
FIG. 3.-SIDE-LIGHTED FACTORIES.
lighted exclusively from the side, or in which the glass
area in the roof was less than 2 per cent. of the floor
area. The extremely low value of the mid-point for
this curve (0.3 per cent.) demonstrates the comparative
inefficiency of side lighting for floor or general illumin-
ation. *



APPENDICES.
41.
GENERAL ANALYSIS (FLOORS).
The following Table and General Analysis are deduced from the Curves in Figs. 1, 2, and 3.
TABLE I.
Percentage of Observations lying below the following Daylight Factors :-
- Below || Below | Below Below | Below Below Below Below Below Below Below Below
0.25. 0–5. 0.75. 1-0. 1-5. 2-0. 2-5. 3-0. 3-5. ſºo. 4-5. 5-0.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) i. (11) (12) (13)
- Per | Per | Per | Per | Per | Per | Per : Per | Per | Per | Per Per
(I) Roof-lighting :- cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Foundries (Curve A) * 15 - 36 54 65 72 77 80 83 86 88
All Factories exclu- — 4' 0 | — 15 27 41 54 65 74 79 83 86
ding Foundries, -
(Curve B).
All Factories inclu- — 8: 5 — 24 39 51 62 69 75 SO 84 87
ding Foundries
(Curve C).
(II) Combined Roof-and
Side-Lighting :-
Foundries (Curve D) * 44 - 75 83 88 93 96 97 98 99 99
All Factories exclu- — 7' 0 || – 22 40 57 71 78 84 89 93 96
ding Foundries
(Curve E).
All Factories inclu- — 27 - 49 62 71 77 82 86 89 92 94
ding Foundries
(Curve F).
(III) Side-Lighting :-
All Factories (Curve G) || 48 71 82 88 95 98 99 * -* - *- *
The mid-points of the curves (i.e. the points above
and below which equal numbers of observations lie) are
approximately as follow :-
Daylight Factor.
Per cent.
I. Roof-lighting :-
Eoundries (Curve A) - - - 1:4
All Factories excluding Foundries
(Curve B) - º g- A- - 2'35
All Factories including Foundries
(Curve C) - - - - - 1 - 95
Daylight Factor.
Summary of Artificial Light Observations.
Measurements of the illumination at floor level were
made in nearly all of the factories visited. Whereas
it was found that in the majority of cases attention was
paid to the “general” illumination of workshops by
providing for a certain number of “general” lighting
units, in some "instances no such provision was made,
the lighting units being placed solely with the object
of illuminating some point of work such as a machine
bed, bench, or loom, and the floor illumination
left to chance. This procedure, though sometimes
yielding fairly good results in practice, was found often
to lead to unsatisfactory, or even dangerous under-illu-
mination of certain parts of the rooms where no work
was being carried on, but over which it was necessary for
workpeople to pass. Some of the rooms in the
spinning mills visited were particularly noticeable in
this respect. In these the lighting units were placed
about 6 feet from the floor, along the alleys between
the frames, the result being that, owing to obstruction
of the light by the frames, the main central alleys,
running at right angles, were left with an amount of
light which appeared to be quite inadequate.
TREQUENCY OF OCCURRENCE CURWES.
It has not been found possible to classify and
summarise the observations on factory floors in tabular
form. Frequency of occurrence curves are, however,
appended, giving :-
(a) The observations in foundries (Curve A);
(b) Those in all factories other than foundries
(Curve B):
Per Cent.
II. Combined Roof and Side-Lighting :-
Eoundries (Curve D) e - - 0. 6
All Factories excluding Foundries
(Curve E) - - º - - 1 - 8 .
All Factories including Foundries
(Curve F) - - gº º - 1:0;
III. Side-Lighting only :- -
All Factories (Curve G) - - - 0 25
(c) Those in all the factories visited, including
foundries (Curve C).
O.2 O.4 O.6 O.8
I.O 1.2
Foot-Candles.
FIG. 4.—FACTORY FLOORs (ARTIFICIAL LIGHT).
1.4 1.6 1. & 2.0
It is desirable to place the foundry observations
in a separate class, since the conditions governing the
arrangement of the lighting in foundries are of a
different nature from those which prevail in other
classes of factories, Further, the proportion of
measurements made in foundries was relatively so
large that an undue influence would be exerted by
them were they to be included with the other obser-
vations.
The chief point to be noted about all three
curves in Fig. 4 is that the slope to the right, is

42
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
fairly gradual, indicating that the mid-point illumi-
nation is often considerably exceeded. At the same
time it should be observed that practically all the
observations fall below 2 foot-candles, only 2 per cent.
to 4 per cent. of the observations lying above this
value. In each curve 2 to 4 per cent. of the observa-
tions lie above 2 foot-candles and have not been
included in the diagram.
GENERAL ANALYSIs FLOORS.
The following Table and General Analysis are deduced from the Curves in Fig. 4.
TABLE II.
Percentage of Observations lying below the following values of Illumination :-
* *- Below Below Below Below Below Below Below Below
0 - 25 () - 5 () - 75 1 - 0 1 - 25 1 : 5 1. 75 2 : 0
ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c.
(1) (2) (3) (4) (5) (6) (7) (8) (9)
| |
{ |
Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent.
Boundries (Curve A) - tºº - 36 63 76 85 90 93 95 96
All Factories, excluding Foundries 24 52 71 83 91 95 97 98
(Curve B). f
All Factories, including Foundries 28 55 71 S2 88 93 96 97
(Curve C).
The mid-points of the curves (i.e., the points above
and below which equal numbers of observations lie) are
approximately as follow :—
Foundries (Curve A) - 0°4 foot-candles.
All Factories, excluding
Foundries (Curve B) - 0° à , 33
All Factories, including
Foundries (Curve C) - 0° 45 ,, 5 3
Curves embodying the separate observations of
floor illumination in the factories of each class have
been included wherever possible in the diagram sheet
for factories of that class, and should be referred to if
a comparison is desired between one industry or process
and another.
The following table summarises the data given in
these individual curves, and shows, for each industry,
the floor illumination above and below which equal
numbers of observations lie :-
TABLE III.
Giving the Mid-point of the Curves for the Floor
Illumination by Artificial Light in each Class
of Factory visited.
| *
Eactory. Fig. Page. *#.
|
--- |
| i | Foot-
Candles.
Foundries gº gº * > 14 57 0.
Engineering shops - - 12 54 0 - 6
Weaving sheds £º tº-º. 6 44 0 - 4
Lace and hosiery factories 10 50 () • 35
Clothing workrooms gº 16 61 0-85
Spinning mills sº tºº 8 47 0 - 6
I.—TEXTILE INDUSTRY.
A.—WEA VING.
Summary of Daylight Observations.
Factories 18, 19, 20, 24, 25, 32, 33, 35, 36, with Room, No. 12a.*
In the eleven sheds visited, the lighting was almost
entirely from north lights in the roof. In no case did
the area of side glass exceed 10 per cent. of the roof
glass. The roof glass area, expressed as a percentage
of the floor area is shown in Table V, and it will be
noticed that this varied very little for all the sheds
visited.
Obstruction by Jacquard harness is a serious
difficulty, comparative observations on neighbouring
looms in the same sheds (Nos. 25a, 25b), jacquard and
plain, gave the following daylight factors:—
TABLE IV.
Jacquard looms. Plain looms.
Per cent. IPer cent.
() - 28 - & tºº ſº tº - 1 -
() - 22 - * = tºg - * - 3' 4
1 - 0 tº - gº 4-, tº - 3 - 9
0' 60 - gº * - *-e cº - I - 9
{). 56 * sº ſº sº tº- - 2 - 7
In shed No. 190 every loom was much obstructed
in this way.
Overhead shafting and belting also causes some
obstruction, and individual electric driving from the
floor as exemplified by No. 35a shows a distinct im-
provement in this direction. In some cases the white-
washing was not as efficient as would be desirable.
The measurements are scheduled below in Table W.
Observations in Room No. 12a are included in the
Table as weaving was being carried on in this room
although there was an absence of the roof-lighting
system which is almost universal in weaving sheds, the
room being simply the ground floor of a spinning mill.
It was lighted exclusively from the side and a com-
parison of the values obtained for the daylight factors
on the looms shows the great inferiority of a side-
lighted room for the purpose. -
It is to be specially noticed that the values of the
daylight factors scheduled in Table W. are only those
observed on looms. The values obtained on the floors
were usually lower than those on the looms. For some
idea of the value of the factor at the floors, the fre-
quency of occurrence curve should be consulted.
* These numbers refer to the factories in the full observations (S.O. Publication).
AppENDíGES.
43
TABLE W.
SUMMARY OF DAYLIGHT OBSERVATIONS IN THE WEAVING SHEDs whº RE MEAstſ REMENTS
ELAVE BEEN MIADE.
- Propor- Total Daylight Factor at
Mean tion of T.l. i.
Room Area. *T**E* * Roof Glass Number Loom.
• , a -w- Height. "... Of Remarks
Number. (Sq. Ft.) (Ft.) Floor Measure- & g
- & Area. ments. Max. Min. |Mean.
(1) (2) (3) (4) (5) (6) (7) (8)
Per Per | Per | Per
- cent. cent. cent cent. -
180, 57,600 15- 34 11 9', 2 : 3 5' 3 Cloths woven varied in coefficient of
: • reflection from 4 per cent. to 56 per cent.
190, 10,500 16 27 8 0. 50 || 0-04 || 0:20 || Much obstruction from Jacquard harness.
- Y. - e * sº
; 5,900 18% 46 5 2 * 2 || || 4 1.3 Coefficient of reflection of cloth woven
O), 35,000 13 29 10 4' 3 2 - 2 || 2: 9 22 t. to 57 t -
24a || 27,000 13; 22 II. 3's 0.8s 2-2 per cent to o, percent. -
§ ; - # ; : º ; : } Some obstruction from Jacquard harness.
32b 10,000 || 17; 46 9 || 2:9 | 1.8 2: . Tapestry (wool of various colours).
350. 20,100 14 26 9 || 6’s 0 44 3' 6 No overhead belting, individual drive.
35b 32,300 15 25 9 4 'o 1 6 || 2: 6 Overhead belting. - -
36a || 47,000 || 13% 32 9 7's 1' 7 4'o | Coefficient of reflection of cloth is 60 per
cent. to 70 per cent. -
12a. 1,360. 9% O 4. 0: 5s 0-11 || 0 |32 | A room used for weaving woollen cloth.
- * No roof glass. Side glass 12 per cent.
of floor area.
FREQUENCY OF OCCURRENCE CURWEs.
Separate frequency of occurrence curves have been
drawn showing:—
(a) The observations on looms at the surface of the
cloth being woven;
(b) The observations at floor level in gangways.
The following points in connection with these curves
should be noted:— -
Looms (Curve A).-The apex of the curve is well to
the right and so may be taken as an indication of a
decided leaning towards a daylight factor at the loom
of about 3 per cent. This practical unanimity might
have been expected from the remarkable uniformity in
the design of all the sheds visited. The mid-point lies
at approximately the same value.
Floors (Curve B).-The daylight factors are con-
siderably lower at the floors than at the looms, but the
curve indicates a less decided leaning to one particular
1 O
value, the gradual slope of the curve to the right
showing that of the observations which lie above the
mid-point value a considerable number tend towards a
relatively high illumination.
2 O
I 5
:
%
O%, 1%. 2% s?, 4% 5% 9%, 10%
e% z% s%
Daylight Factor (Percentage of Outside Illumination).
FIG. 5–WEAVING SHEDs (DAYLIGHT).
•
GENERAL ANALYSIs (WEAviNg SHEDs).
The following Table and General Analysis are deduced from the Curves in Fig. 5, -
TABLE VI.
Percentage of Observations lying below the following Daylight Factors :—
&ºmºsºms-tº-s Below Below Below | Below | Belo Below Below Below | Below Below
0 - 5, 1 * 0. 1 : 5. 2 : 0. 2 - 5. 3 * 0. 3 - 5, 4 * 0. 4 5. § - 0.
(1) (2) (3) (4) (5) (6) (7) (8) (9) I (10) (11)
Per Ber Per Per Per . . . . Per Per Per Per Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Tooms (Curve A) *E- tº- 3 8 : 5 16 26 42 61 77 85 89 92
Floors (Curve B) - - || 10 30 51 69 80 87 92 95 97 99
The mid-points of the curves (i.e., the points
approximately as follow:—
Looms (Curve A) -
a 30030
2.7 per cent.
above and below which equal numbers of observations lie) are
Floors (Curve B) - 1° 5 per cent,
E

44
i) EßARTMENTAL COMMITTEE on LIGHTING IN FACTORIES AND WORKSHOPS : .
Summary of Artificial Light Observations.
Factories 18, 19, 20, 24, 32, 33, 35, 36, with Room No. 12a.
Of the eleven sheds visited, artificial light measure-
ments were made in nine.
In the majority of cases the lamps were shaded by
enamel or opal shades of the ordinary shape, but in
one shed (No. 36a) the new form of metallic reflector
was in use, and was stated to have been found a
distinct improvement. The usual method of placing
the lights is to have one lamp over every pair of looms,
or in cases where the candle-power of the lamp is
%igher, one over the centre of every group of four
looms.
The usual height of the lamps is, as will be seen
from the table, from 5 to 7 feet, that is to Say, as low
was very noticeable.
as possible without causing inconvenience to the
operatives in moving about under them. With such
an arrangement as this it is clear that the ordinary
form of shade is unsatisfactory on account of the glare
due to the rows of bare lamps seen on raising the
eyes from the looms. The improvement in this direc-
tion due to the use in some cases of metallic reflectors
The observations (at looms only) are scheduled in
Table VII., to which, as before, the observations in
room No. 12a, have been added. This was not a
shed, but a ground floor room for weaving woollen
cloths of various colours.
TABLE VII.
SUMMARY OF THE ARTIFICIAL LIGHT OBSERVATIONS IN THE WEAVING SHEDS WHERE MEASUREMENTS
- HAVE BEEN MADE. -
Height of > Illumination at Loom
Room Floor Area Hºº Number of (Foot-Candles).
* Lighting Measure-
Number. (Sq. ft.). U. lºve - ments - Remarks.
Floor (Ft.). 2. Max. Min. Mean.
(1) (2) (3) (4) (5) (6) (7) (8)
180, 57,600 6 9 12 5 6 - 5 8: 7 | Lighting very good.
19q. 10,500 5 9 5 : 3 1 25 2 : 15 .”
19b 5,900 5 5 2 : 10 1 25 1 55
200, 35,000 4% 10 3.7 2 - 0, 2:7;
24a. 27,000 5 11 5 8 1 - 85 3 : 6
32b 10,000 Various 8 2 65 1 : 50 2 : 0s
35a, 20,100 7 9. 2' 30 1'45 1 65
35b 32,300 ... 7 10 1 40 () . 73. 0 '98 . -
36a 17,000 8 9 1.90 0 - 66 1 : 10 | Electric lamps in metallic reflectors
each illuminating four looms.
12a | 1,360 6# 4 2 : 0% 1' 40 1 60
FREQUENCY OF OCCURRENCE CURVES.
Frequency of occurrence curves are given in Fig. 6.
These embody the results obtained in all the weaving
sheds visited :— w
(a) on looms.
(b) on floors.
The observations taken in room No. 12a, have not
been included in the curves. The following points
should be noted:—
Looms (Curve A).--The slope of this curve to the
right is fairly gradual but the curve indicates a decided
leaning towards an illumination of between 1 and
2 foot-candles at the surface of the cloth on looms.
Two per cent. of the total number of observations lie
above 10 foot-candles and have not been included in the
diagram. -
Floors (Curve B).-Practically the whole of this
curve lies below the 1 foot-candle point, while the mid-
point indicates that one-half the observations lie below
0 4 foot-candle. - • .
*
\\
20
15
I O
5
O
O I 2. 6 z-
5. 4: .5 & 9.
Foot-Candles.
'IO
15
10
5
O
OO
O.5 1.0
3.0
J.F.; 2.0 2.5
Foot-Candles.
FIG. 6.—WEAVING SHEDS (ARTIFICIAL LIGHT).
3.3 <+,O
GENERAL ANalysis (WEAVING SHEDs).
The following Table and General Analysis are deduced from the Curves in Fig. 6.
TABLE VIII.
Percentage of Observations lying below the following values of Illumination —
Below | Below || Below | Below || Below | Below | Below | Below | Below Below Below | Below
() • 25 0 - 5 () 75 1 - 0 1 : 5 2 : 0 2 - 5 3 - 0 3 - 5 4 - 0 4 - 5 5 - 0
ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c.
(1) (2) (3) (4) (5) (6) (7) | (8) (9) (10) (11) (12) (13)
Per | Per | Per | Per | Per | Per | Per | Per | Per | Per | Per | Per
. . . . cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. ,
Looms (Curve A) - - || – || 3 - 18 36 52 64 72 77 81 83 || 85
Floors (Curve B) - - 28 || 66 88 93 100 | – || – || – || – | – || – || –
The mid-points of the curves (
approximately as follow:—
Looms (Curve A) -
- 2 foot-candles.
Floors (Curve B) -
- 0°4 foot-candles.
7.e., the points above and below which equal numbers of observations lie) are


APPENDICES.
B—SPINNING, ETC, AND INCIDENTAL PROCESSES.
Summary of Daylight Observations.
Factories 12, 14, 18, 19, 20, 26, 27, 31.
T)aylight measurements were made in 22 rooms.
The processes carried on in these rooms included
scribbling, drawing, roving, reeling, cap spinning, mule
spinning (6 rooms), weft winding, joining, preparing,
and finishing. The mule spinning rooms have been
classed together at the end of this table, Room No. 14a
being included among them, although part of it was
used for the process of drawing. The remaining rooms
have been placed together at the beginning of the
table in order to show the considerable obstruction of
light which takes place owing to the placing in most
of them of high machines close together. Undesirable,
and even dangerous under-illumination of gangways
frequently arose from this cause, particularly as the
rooms were of considerable width, low, generally without
roof glass, and often with a much smaller area of side
TABLE
glass than might have been provided. Factory No. 14
may be taken as an example of good Side-lighting, the
rooms being lofty and provided with the maximum
area of glass possible, Room No. 14a was below
ground level, but the windows were provided with
prismatic glass. The whitewashing of the walls did
not always seem to have received adequate attention,
and improvement in this direction might have had an
appreciable effect on the illumination, especially of the
side-lighted rooms most often met with.
The measurements made on floors have been
omitted in considering the minimum and mean illumi-
nations given in the table, so that these include only
the observations made on a horizontal plane at actual
places of work. For the floor illuminations the
frequency of occurrence curve should be consulted.
*
IX.
SUMMARY OF THE DAYLIGHT FACTORS IN THE SPINNING MILLS IN WHICH MEASUREMENTS
: EIAVE BEEN MADE. -
- Propor- Propor- º º
Floor Mean tion of tion Of Number Daylight Factor at
Room ...T. Width.| ROOf Side - Point of Work.
Area. | FIeight. Glass Glass Of Process.
* (sq. F.) (Fº) (Ft.) | *...* | *...* Readings. - •
Area. Area. Max. Min. Mean.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
(a) Rooms containing much Machinery : Per | Per | Per
| Per cent. Per cent. cent. cent. cent. -
12b 3,000 9% 35 0 9 . 6 2-9 || 0:36 1:2 Scribbling (woollen).
14b 16,950 | 1.4% | 84 0 26 7 4's 0:0, 1.9 Drawing (worsted).
14c 16,950 | 1.4% | 84 () 26 5 6's 0'0s 2 5 | Cap spinning (worsted).
18b 3,630 | 15% 33 37 10 6 6' 6 || 0 30 3's Finishing (worsted cloth).
20b 18,100 | 13 | 104 || 15 () 11 4 - 4 || 1 7 3's Winding (flax).
190 4,130 13 43; () 10 6 1.2 0.035 | 0:28 2, 2,
196, 628 11% 29 () 15 5 1 - 0 || 0 3, 0' 60 Joining (flax).
19e 8,500 13 63% 10 4 11 3's 0-06 | 1.3 | Preparing (flax).
19 f 6,100 11% | 44 0 13 7 1 5 || 0-09 || 0 8s | Spinning (flax).
19q 10,000 | 12 52 () 10 7 1 - 9 || 0 - 12 0 8s , ,
19%. 10,000 | 15 52 12 7 | 7 4' 6 || 0:44 2-7 | Reeling (flax).
31c 2,200 | 12% 52% 2 6 - 5 6 2 : 0 || 0-06 || 0: 5s ,, . (Cotton).
260, 13,100 || 14 | 118 5 3 - 5 9 1:6 || 0:02 || 0-3 || Roving ,
27a. 36,500 13% 144 () 7 11 || 3: 6 || 0-08 || 1 | 1 || Roving and carding(cotton).
31b 2,200 10 52; - 5 : 5 8 . 0. 59 || 0:01 || 0 |17| Roving and ring knitting
(cotton).
(b) Mule Spinning Rooms :
12c 3,110 7 35 9 () 4. 1' 7 || 0:49 0-90 (Woollen.)
I2d, 1,740 7 35 8 - 5 1 3 1.6 || 0 90 1 3 33
12e 1,400 7% 25 () 9 4. 5 : 3 || 0 07 2 : 1 35
14a. 16,950 | 12 84 () 17 6 9 : G | 0-03 || 1:8 (Worsted.)
26b 10,950 11 118 () 8 6 4's 0° 04 || 1:9 (Cotton.)
27b 38,600 | 12 144 () 5' 5 7 . . .11 0.03 || 3: 6 55
FREQUENCY OF OCCURRENCE CURWEs,
Frequency of occurrence curves are given in Fig. 7.
These include — - -
(a) The observations at all the chief types of
machines (except mules) used in the spinning
mills visited. - -
(b) The observations on spinning mules.
(c) Those on the floors of all the spinning rooms
visited.
The following features in connection with the
curves should be noted — ,
Machines (Cwrve A).-The high values of the
curves at the lowest daylight factors indicate a con-
siderable amount of bad lighting (owing, generally,
to obstruction of the side light by machinery). About
2 per cent. of the observations lie above a daylight
factor of 5 per cent, and so have not been included in
the diagram, -
E 2
46
DEPARTMENTAL CoMMITTEE ON LIGHTING IN FACTORIES AND workshops:
6O
5 O
24 O
a;O
2O
I O
O
I O
O H.
I O
O
O.O% O.5% 1.0%, 1.5% 2.0%, 2.5%a.0% a.5% 4.0%, 4.5%, 5.0%
Daylight Factor (Percentage of Outside Illumination).
FIG. 7.—SPINNING MILLS (DAYLIGHT).
Mules (Curve B).-The low illumination here is
less due to obstruction by machinery than to the great
width of the rooms compared with their height. This
width introduces a large diversity into the readings
obtained in any one room, the useful illumination at
the side of a typical mule-spinning room (No. 27b)
being 20 to 40 times as great as that in the middle of
the room. About 13 per cent. of the observations lie
above a daylight factor of 5 per cent., and so have not
been included in the diagram.
Floors (Curve C).-The low illumination indicated
by this curve is produced by either or both of the
causes noted under the above curves. About 4 per
cent. of the observations lie above a daylight factor
of 5 per cent., and have not been included in the
diagram.
GENERAL ANALYSIs (SPINNING MILLs),
The following Table and General Analysis are deduced from the Curves in Fig. 7:—
TABLE X.
Percentage of Observations lying below the following Daylight Factors —
cº-º-º-º-º- Below | Below Below | Below Below | Below Below Below Below | Below
() • 25, () : 5. 0 - 75. 1 * 0. 1 : 5. 2 : 0. 2 : 5. 3 - 0. 3 - 5. 4 - 0.
—l- (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)
Per | Per | Per | Per | Per | Per | Per | Per Per | Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Machines (Curve A) - º - - || 30 46 54 60 68 74 79 83 86 89
Mules (Curve B) - º - - 35 52 59 63 70 74 77 80 83 85
Floors (Curve C) - -> - º 29 41 49 56 67 76 82 88 92 95
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie) are
approximately as follow :-
Machines (Curve A) - tº
Mules (Curve B) 4- &E-
Floors (Curve C) * * -
Daylight Factor.
& º- - 0. 6 per cent.
- - - 0° 5 ,,
0.8 22
Summary of Artificial Light Observations,
Factories 12, 14, 18, 19, 20, 26, 27, 31.
Measurements were made in all the 22 rooms visited.
The processes carried on in these rooms included
scribbling, drawing, roving, reeling, cap spinning, mule
spinning (six rooms), weft winding, joining, preparing
and finishing. The table summarising the daylight
factors has been divided into two sections:—
(a) All rooms containing much machinery.
(b) Mule-spinning rooms.
The systems of lighting met with included batswing
gas burners, incandescent mantles, both upright and
inverted, high-pressure gas, and electric glow lamps.
The obstruction of light by machinery was particularly
noticeable in most of the rooms of Class (a), and in
many cases where no special lights were provided to
illuminate the gangways, the latter were often found
to be very badly under-illuminated.
The measurements on floog's have been omitted in
considering the minimum and mean illuminations
given in the table for the various rooms, so that these
records include only those observations made at actual
places of work. For the floor illumination in spinning
mills, the frequency of occurrence curve should be
consulted.
TABLE XI.
SUMMARY OF THE ARTIFICIAL LIGHT OBSERVATIONS IN THE SPINNING MILLs whºRE MEASUREMENTs
HAVE BEEN MADE.
Distance of Chief , Illumination at Point of Work.
Room Floor Area. . º tº: Nº. (Foot-Candles.) Proces
Number. (Sq. Ft.) above Floor. . Measure- l’OCéSS.
(Ft.) - ments. Max. Min. Mean.
(1) (2) (3) (4) (5) |_(6) (7) (8)
(a) Rooms containing much Machinery :-
12b 3,000 5; 6 0 - 48 0 - 15 0-26 Scribbling (woollen).
14b 16,950 6 8 3 - 5 0 - 43 1'45 Drawing (worsted).
14c 16,950 7 5 3' 4 0.86 || 1:45 Cap spinning (worsted).
18b 3,630 5 and 7 6 4' 6 () - 67 2' 30 Finishing (worsted cloth).
20b 18,100 # 11 4 - 0 0 - 61 2-10 || Winding (flax).
19e 4,130 # 6 (). 93 || 0 , 52 0 - 70 25 33
190, 628 - 5 11's 1' 20 5' 6 Joining (flax).
19e 8,500 6 11 0 - 77 || 0 - 16 0.38 | Preparing (flax).

APPENDICES. - -- 47
e . . . . Illumination at Point of Work.
Room | Floor Area. | P:sºnºe of Chief Number (Foot-Candles.) -
Lighting Units Of *. Process
Number. (Sq. Ft.) above Floor. Measure- e
- (Ft.) . ments. Max. Min. Mean.
(l) (2) (3) (4) (5) (6) (7) - (5)
(a) Rooms containing much Machinery—continued. .
19 f 6,100 6 7 2' 35 1. 0s 1 ° 45 Spinning (flax).
19q 10,000 5% 7 1' 40 0 - 49 0 '82 35 2, -
19h. 10,000 6 7 1.90 1 : 10 1 : 50 Reeling (flax).
31c 2,200 6# 6 l' 20 0 - 15 || 0 65 , (cotton). -
26a | 13,100 7 9 1.90 0.03 || 0:44 || Roving (cotton).
27a. 36,500 8 11 1° 55 || 0:045 || 0:44 Roving and carding (cot-
- - ton). -
31b 2,200 6# 8 0 - 68 || 0 - 14 0 °37 | Ring knitting (cotton),
(b) Mule Spinning Rooms :- () 21 () 06 0-11 (Woollen).
12c 3,100 5#. 4. 0. 51 || 0 - 06 0 24 99
12d, 1,740 5% 3 0.79 || 0:08, 0 48 3 *
12e 1,400 5#. 4 1.05 0 - 42 * Mule spinning (worsted).
On mules 2 3. 0.56 1 : 50 | Drawing (worsted).
140, 16,950 7 & 10 { On frames 5 2 - 8 0 - 20 1 ° 25 (Cotton).
26b 10,950 6 5 0 - 67 || 0 - 14 0 - 39 5 s
27b. 38,600 7 6 ---
FREQUENCY OF OCCURRENCE CURVEs. - The following features in connection with the
Frequency of occurrence curves are given in Fig. 8. ** should be noted :- * * •
These include:— Machines (Curve A).-The slope of this curve to the
vafi * right is unusually gradual and declines from a peak at a
(a) º machines of all types excep t very low value of illumination, showing that there is a
(b) The observations at spinning mules. considerable diversity in the values observed with a
(c) All measurements taken at floor-level. tendency towards an exceedingly low illumination in
gº many mills. Approximately 3 per cent. of the obser-
2 *- vations lay above 4 foot-candles and have not been
4:O
included in the diagram as it was not thought desirable
30 to reduce the scale to the extent necessary for the
20 inclusion of these points.
I O Mules (Cwrve B).-The shape of this curve indicates
O that there is less diversity in the illumination of mules
than is the case with the machines dealt with
in Curve A. It will be seen from the table, how-
1 O. ever, that over 60 per cent. of the illumination obser-
O
vations at spinning mules lie below 0.5 foot-candles.
Floors (Curve C). This curve includes the observa-
tions on the floors of all the machine rooms visited,
I O
%.o o,5 Lo 1.5 2.0 2.5 a.o. 3.5 4.0 and therefore includes all processes carried on in
Foot-Candles spinning mills. It is similar in shape to the previous
g curve (B) except that the higher values of illumination
FIG. 8.-SPINNING MILLS (ARTIFICIAL LIGHT), are better represented,
- GENERAL ANALYSIs (SPINNING MILLS). -
The following Table and General Analysis are deduced from the Curves in Fig. 8.
TABLE XII.
Percentage of Observations lying below the following values of
Illumination :- -
Below | Below || Below Below Below Below Below Below | Below Below
0 - 25 || 0 - 5 || 0 75 || 1 - 0 I 5 2 . () 2 - 5 || 3 - 0 3 - 5 4 - 0
ft.C. ft.C. ft.c. ft.c. ft.C. ft.c. ft.c. ft.c. ft.c. ft.c.
(1) (2) (3) (4) (5) (6) (7) | (8) (9) (10) (11)
Per | Per | Per | Per | Per | Per | Per | Per | Per | Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Machines (Curve A) . . . . . 23" || 40 || 5 || 6 || 79 || 8 || 51 || 9 || 93 || 9 |
Mules (Curve B) - - - - || 32 61 76 | 84 || 92 || 97 100 | – || – || –
Floors (Curve C) - - - - 22 45 58 69 | 84 93 98 || 100 | – || –
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie) ar
approximately as follow:— -
Machines (Curve A) - - - - * : 0-6, foot-candles.
Mules (Curve B) º * . sº - gº wº - 0° 4 55 5, 9
Floors (Curve C) - {-} tº gº tº - 0. 6 -
33 3:
a 30030 E 3

DEPARTMENTAL committer, ON LIGHTING IN FACTORIES AND WORKSHOPS :
C.—LACE AND HOSIERY MAKING.
Summary of Daylight Observations.
Factories 38, 39, 40, 41.
(a) Lace Factories. - The total number of lace-
making rooms in which measurements were made was
10. In only two of these were there any roof lights.
In one (mending room No. 38a) 2.1 per cent, and in the
other (machine room No. 38b) 27 per cent of the roof
area was glass. The improvement in the light for this
factory was very marked. In every other case lighting
was exclusively from the side. - -
The daylight factors are scheduled in the table,
the rooms being divided according to the different
processes chiefly carried on in them. In considering
the minimum and mean daylight factors given in the
table, only observations taken at actual places of work
have been included. For the floor illumination the
frequency of occurrence curve should be consulted.
(b) Hosiery Factory.—The results for the single
factory visited (four rooms investigated) are entered
in the same table and a separate frequency of oc-
currence curve for the weaving process in this factory
is added. The floor daylight factor in this factory
varied from 0 1 to 0° 5 per cent,
TABLE YIII.
SUMMARY OF THE DAYLIGHT OBSERVATIONS IN THE LACE AND HOSIERY FACTORIES WHERE
MEASUREMENTS HAVE BEEN MADE. -
Propor- | Propor- Number Daylight Factor at
. ! ~~~ *. * ºn's a. WIlght H'a,CUOI’ a.
Floor Mean || "... "..." f i."."
Room Area Height, Glass Glass OI º
• . Area to Area to Measure- |T Process.
Number. (Sq. Ft.) | Ft. Floor Floor . - - * { *t ºr e
- - Area. Area. ments. Max. | Min. Mean.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Lace Factories :— Ber cent. Per cent. -
380, 1,340 | 18 2I 4' 5 6 2.5 || 0:8, 2-0 || Mending.
416 3,020 | 15 () II. 9 3. * | 0-05 || 1:7 | Finishing.
39c 1,270 9. () 23 5 1-1 || 0 3, 0-7, Winding.
390, 1,360 14 () 22 9. 1. 7 || 0:21 || 0: 5s | Slip winding. .
38b 13,600 | 18% 27 6 - 5 L0 3 o || 0 54 || 1 | 5 | Curtain weaving.
39a 2,370 113 () 13 6 1 - 7 || 0 02 || 0 4s 5 5 5 5 Workers dis-
satisfied.
39b 2,340 | 12 () 16 6 2' 6 || 0 14 || 0 | 84 33 35 5 3 33
41a. 4,080 14 () 22 8 1-1 || 0-09 || 0-6, 35 33 35 3 5
41b 2,670 11 () 18 6 1. 3 || 0 - 07 || 1 - 0 35 55 35 55
41d. 5,610 | 12 () 18 7 1.8 || 0 - 18 || 0-9, 55 5 5 3. 33
Hosiery Factory :—
40a || 4,070 14 0 17 9 4' 0 || 0-30 || 1 | 6 || Weaving.
40c 1,900 | 12 I 9 - 5 8 2 - 5 || 0 - 22 || 1 3 9 3
40d 4,070 || 14 () 23 12 5's 0 - 27 | 1.8 9 3
40b 2,000 | 12 () 9 9 0.3s 0-01; 0 18 || Winding. Basement. Daylight
. generally reinforced.
FREQUENCY of OccuRRENCE CURVEs.
Frequency of occurrence curves are appended.
These include the results of observations On:—
(a) Lace-making machines. -
(b) Floors in the lace factories visited.
Il
:
l
i
§ 0.0% O.5% 1.0% 1.5%; 2.0% 2.5% a.0% a.5% 4.0%
Daylight Factor (Percentage of Outside Illumination.)
FIG 9,-LACE AND HOSIERY FACTORIES
(DAYLIGHT),
(c) Machines in the one hosiery factory visited.
(d) Winding machines, both in lace and hosiery
factories.
The number of observations in all four cases was
not sufficient to give any great definiteness to the
curves, and so any data deduced from them can only
be regarded as approximate. From the twelve obser-
vations in examining and mending rooms, the daylight
factor at the places where such work was being carried
on seemed to average about 1 7 per cent.
The following points in connection with the curves
should be noted:—
Lace Machines (Curve A).-The very gradual slope
of this curve towards the right indicates that there are
a large number of observations which greatly exceed
the mid-point value. Owing to the small number of
observations available, however, the shape of the curve
is rather indefinite.
Floors in Lace Factories (Curve B).-By far the
greater part of this curve lies below a daylight factor
of 0.5 per cent. The two small humps on the right
are due to observations in the two roof-lighted rooms.

APPENDICEs.
49
Machines in Hosiery Factory (Curve C).-The same
remarks as those made on Curve (A) above apply also
to this curve. Approximately 9 per cent. of the obser-
vations lay above a daylight factor of 4 per cent, and
so have not been included in the diagram as it was not
thought desirable to reduce the scale to the extent
Winding Machines (Curve D).--Almost the whole of
this curve lies below a daylight factor of 0° 5 per cent.
Some specially low values result from the inclusion of
readings in Room No. 40b, which was a basement room
in which artificial light was often used in the daytime
necessary for the inclusion of these points.
observations,
GENERAL ANALYSIs (LACE AND HosſERY FACTORIES).
The following Table and General Analysis are deduced from the Curves in Fig. 9.
though, of course, turned out during the taking of the
TABLE XIV.
Percentage of Observations lying below the following Daylight Factors:–
Below Below Below Below || Below Below Below Below Below Below Belo Below
0.25. 0-5. 0.75. 1-0. I 25. 1 : 5. I 75. 2 * 0. 2 : 5. 3 - 0. 3 - 5. 4 - 0
(l) (2) (3) (4) (5) (6) (7) | (8) (9) (10) (11) (12) (13)
Per | Per | Per | Per | Per | Per | Per | Per Per | Per | Per | Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Lace Machines (Curve 21 41 56 67 77 84 89 93 99 sº-sº - *
A). - - . -
Floors in Lace Factories 37 || 65 75 80 85 | 89 92 94 97 98 || 99 *
(Curve B). . . . . . -- . . . -
Hosiery Machines 7.5 25 41 52 60 66 71 75 81 86 89 91
(Curve C). - -- - -
Winding Machines 35 69 85 90 94 96 97 98 99 99 * smº-sº
(Curve D). - -

The mid-points of the curves
approximately as follow —
Lace Machines (Curve A) - tº
Floors in Lace Factories (Curve B) -
Hosiery Machines (Curve C) - tº
Winding Machines (Curve D) º
(i.e., the points above and below which equal numbers of observations lie) are:
Daylight Factor.
0.65 per cent.
us *g & 0 35 5 3 2 3
tº-º & . . () 95 35 53
gº tº ſº () 35 3 y 39
Summary of Artificial Light Observations.
Factories 38, 39, 40, 41.
(a) Lace Factories.—Of the 10 rooms visited, two
were lit by electric incandescent lamps alone, four by
high-pressure gas (in one case with a subsidiary system
of electric lighting) and four (Factory 39) by batswing
burners. The last named system was obviously quite
insufficient and the workers complained of the poorness
of the illumination. It will be seen from the table
that the average illumination is, on the whole, very
much lower for the rooms of this factory than any of
the other rooms visited except Room No. 41a. In this
the machinery was of a special kind requiring but
little close attention.
machine rooms the chief desideratum is a moderate
general light over all the working parts, and the
possibility of producing a high local illumination at
any desired spot when required. For this purpose the
most suitable system of lighting seen consisted of
counter-weighted lamps, capable of being readily
pulled down and directed towards any particular point
which it was desired temporarily to illuminate for the
purpose of piecing a thread or otherwise supervising
the working of the machine. It is desirable that the
lamps should be shaded for the reason mentioned in
the memorandum on weaving sheds (p. 40).
In the large majority of lace
. (b) Hosiery Factory.—The single factory visited was
lit mainly by electric light. The system of batswing
burners was used only to reinforce the natural lighting
on dark days. The illumination produced seemed
generally sufficient but the lighting units were so placed
that the workpeople, while tending their machines,
were compelled sometimes to stand in their own light.
Several complaints on this ground were received from
the workers, and an observation taken on the machine
with the operative in his normal working position gave
an illumination of 0° 15 foot-candles, while the un-
obstructed illumination averaged 1 foot-candle. Here,
again, more local lighting seemed to be desirable, and
adjustable lights would undoubtedly have been a
considerable convenience. -
More measurements in hosiery factories would be
needed before it could be said whether those here
given may be regarded as representative.
In considering the minimum and mean illuminations
given in the table, only observations taken at actual
places of work have been included. For the floor
illumination the frequency of occurrence curve should
be consulted.
TABLE XV.
SUMMARY OF THE ARTIFICIAL LIGHT OBSERVATIONS IN THE LACE AND HostERY FACTORIES
WHERE MEASUREMENTS HAVE BEEN MADE. -
Distance Illumination at Point of Work.
- - - Floor Area. of Chief Number || (Foot Candles.)
Room Number. Lighting Measure- Process.
(Sq. Ft.). º: º: ments, Max. Min. Mean. -
(1) (2) (3) (4) (5) (6) (7) (8)
- - | -
Lace Factories :— - - |
- 38a. 1,340 || 6 || 6 || 2:5, 0-30 || 1:0. Mending.
41c 3,020 6 9 4-8 0-60 || 2:3, Finishing room.
39c 1,270 Various 5 1.9, 0 - 06 1 20 Winding.
E 4.
50. DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
Distance | \,: Illumination at Point of Work.
- Floor Area. of Chief Number (Foot-Candles.)
Room Number. Lighting wº e-T Process.
(Sq. Ft.) . º mentS. Max. Min. Mean.
(1). (2) (3) (4) (5) (6) (7) (8)
| -*
Lace Factories—cont. - - e e - sº
39d 1,360 Various 8 2' lo (): 73 1' 30 Slip winding.
38b | 13,600 6 10 2.85 0 - 13 0 '98 | Curtain weaving.
390, i 2,370 || Various 5 1 - 05 0 - 06 || 0 - 58 35 53
39b 2,340 6 1 : 15 () - 06 0 ° 42 33 5 3
41a. 4,080 9% 8 0 - 59 0 - 13 0 ° 45 33 35
41b 2,670 4% 5 1-9, 0. 54 1 25 35 5 3
41d 5,610 5% 7 8 : 6 () 28 2 25 33 55
Hosiery Factory :- - g
40a. 4,070 5% 2 : 50 0 ° 45 1' 40 Weaving.
40c 1,900 5% 8 4 - 7 () - 82 2' 40 35
40d 4,070 5% 12. 10 : 0 0 - 4.1 2 35 • *.
40b 2,000 6 9 1° 55 0. 58 1 : 00 Winding.
FREQUENCY of OccuRRENCE CURVEs.
Frequency of occurrence curves are given in Fig. 16
for the illumination at lace-making machines and at the
floors of all the rooms visited. A separate curve shows
the results obtained at the machines in the hoisery
factory. .
sº
Hº;
IO
5
:
O.5
H.O 1.5 2.0 2.5 3.0
Foot-Candles.
3.5
FIG. 10.-LACE AND HOSTERY FACTORIES
(ARTIFICIAL LIGHT).
The average floor illumination in this factory was
about 0.5 foot-candles. The observations at winding
machines in both lace and hoisery factories are in-
cluded in a single curve. Owing to the comparatively
few observations available none of the curves are
perfectly definite, and any data deduced from them
<20
can only be regarded as approximate. The number of
observations in examining and mending rooms (11) was
not sufficient to allow a curve to be drawn, but the
illumination was found to vary from 0 3 to 4 5 foot-
candles, with an average of 2 foot-candles. The
following points in connection with these curves should
be noted:—
Lace Machines (Curve A).--The mid-point of this
curve lies at 0-7 foot-candles, but, as noted in the
remarks above, the observations embodied in this
curve refer mainly to the general illumination, and not
to the local illumination available at need. The
gradual slope of the curve indicates that the illumina-
tion at the mid-point is frequently exceeded to a
considerable extent. -
Floors in Lace Factories (Cwrve B).--This curve
does not extend above 1 foot-candle, there being no
recorded illuminations higher than this on the floors
of lace factories. The mid-point is below 0°4 foot-
candles, indicating that comparatively little attention
can have been paid to the general illumination.
Hosiery Machines (Curve C).-Here, again, the
curve slopes gradually to the right for the same reason
as that noted in curve (A). Approximately 3 per cent.
of the observations lie above 4 foot-candles, and so
have not been included in the diagram.
Winding Machines (Curve D).-This curve embodies
the observations on winding machines in both lace and
hosiery factories. Again a gradual slope to the right
is noticed, giving a mid-point at an illumination of
about 1 foot-candle. -
GENERAL ANALYSIS (LACE AND HostERY FACTORIES).
The following Table and General Analysis are deduced from the Curves in Fig. 10.
TABLE XVI.
Percentage of Observations lying below the following values of Illumination :-
*-*-* *- Below Below Below Below Below | Below Below Below Below Below Below Below
0 - 25 () - 5 0 - 75 1 : () 1 ° 25 1 : 5 1 - 75 2 . () 2 - 5 3. 3 - 5 4 - 0
ft. c. ft. c. ft, c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c. ft. c.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (1]) (12) (13)
Per | Per | Per | Per | Per | Per | Per | Fer | Per | Per | Per | Per
* cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Lace machines (Curve A) 10 34 53. 65 72 78 83 86 91 95 tº- -
Floors in lace Factories 32 73 96 100 *- --- - a- - -- s- -
(Curve B). -
Hosiery machines (Curve | 0 5 4 || 13 30 47 60 69 75 84. 90 94. 97
C).
Winding machines - 6 - 5 25 47 65 78 87 92 97 99 —- —
(Curve D).
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie) are
approximately as follow :—
Lace machines (Curve A) - 0 - 7 foot-candles.
Floors in Lace Factories (Curve B) - & - - 0° 35 , ,,
Hosiery machines (Curve C) g- dºe º - 1 3 , ,,
Winding machines (Curve D) sº & º - 1:0s , ,

APPENDICES.
51
II.-ENGINEERING INDUSTRY.
A.—GENERAL ENGINEERING (eaccluding Foundries).
Summary of Daylight Observations.
Factories 3, 4, 6, 10, 16, 17, 28, 37, 50.
The total number of shops in which daylight
measurements were made was 43 (two of these, how-
ever, had so little daylight available that artificial
light was used practically throughout the day). Both
side-lighted and roof-lighted shops were met with, and
in the majority of cases a combination of both systems
W8,S IIl Ulsé. -
The daylight factors are scheduled in the table and
in this the shops are divided into four classes accord-
ing to the nature of the work chiefly carried on in
them. In Class I. are placed shops in which the chief
duty of the operatives was the care of such machines
as lathes, planing and drilling machines, and others
which, Once set in action, do not require close atten-
tion or accurate adjustment while running. In many
of these shops each machine was provided with a small
local adjustable light for use as required. The day-
light factors were, of course, calculated from measure-
ments made with this local light out of use, and they
do not give the maximum illumination attainable on
such machines when the daylight was reinforced with
artificial light. In many cases the machines them-
selves or, more frequently, the overhead shafting and
belting caused considerable obstruction. Individual
electric drive would seem to offer an improvement in
this direction, but was not met within any of the shops
visited except for very large machines.
In Class II. of the table are placed shops in which
the chief work is of the nature of bench work, includ-
ing fitting, finishing, and polishing of small parts and
similar processes. For such work more light is
required than for the less fine work of Class I. This fact
seems to have been recognised to a certain extent by
placing benches as far as possible near windows, but as
the designs of the shops did not ever appear to differ
appreciably from those of the other machine shops, the
increase of light thus obtainable was limited in amount.
Further, it must not be assumed that the two classes
of work were always met with in distinct buildings.
This was not the case, and in the majority of shops
both classes of work were being carried on simultane-
ously. The shops have been grouped according to the
class of work which preponderated. In the case of
such a combination of both kinds of work in One shop,
the tendency was usually, though not invariably, to
place the machines in the centre, and the benches at
the sides of the shops. Particularly fine work such as
engraving on metal requires special treatment in the
placing of machines. In the particular engraving
machine on which measurements were taken (in Shop
No. 10c), the daylight factor was approximately 6 per
cent. On the bed of the machine.
In Class III. of the table are placed shops in which
heavy work, such as forging, &c., is carried on. The
illumination in such cases is usually very general, no
local artificial lights being provided in the majority of
instances.
Class IV. contains the results for the four wood-
working and pattern-making shops visited.
The measurements on floors have been omitted in
considering the minimum and mean illuminations
given in the table, so that these include only observa-
tions made at actual places of work. For the floor
illumination the frequency of occurrence curve should
be consulted,
TABLE XVII.
SUMMARY OF THE DAYLIGHT OBSERVATIONS IN THE ENGINEERING Works wherE MEASUREMENTS
HAVE BEEN MADE.

Pro- Pro- Daylight Factor at
room | Floor Mean *.*.*." sº Point of Work.
T Area. Height. Glass Glass O
Number. (Sq, Ft.) (Ft.) * *...* Measure- e Remarks.
Area. Area. ments. | Max. Min. Mean.
(l) (2) (3) (4) (5) (6) (7) (8) (9)
- | .
Class I.--—Machine Shops : Per Per Ber | Per | Per
. cent. cent. cent. cent. cent.
3d 24,200 20 44 () 5 6 : 4. 1 - 3 8 -
4b 6,400 32 19 5 5 0 - 7, 0.19 || 3's Windows extremely dirty.
6b 8,200 20 () 14 7 1:7 0' 013 || 0 60
10d. 42,000 33 22 37 17 8 : 6 0 - 50 || 2 | 1
10e No observations. -
10f 5 5. 5 5
10g 19,600 26 28 4. 9 6 ‘o 0.04 || 2:7
10! 75,600 29 48 3.5 20 8 4 0 - 14 2 - 2
100m, 7,800 | 16 33 23 7 5' 6 || 1:2 || 3:4 A side gallery in a larger room.
16c II,700 20 19 12 8 4' 0 0-40 || 2: 2
16e 8,200 43 20 3 - 5 5 2 - 5 0 - 26 || 1 4
16f 15,500 36 32 4 - 5 8 3 - 4 0 - 29 || 1 | 6
16g 24,800 || 45 85 46 4. 7 's 5's ---
16] 34,000 36 45 10 6 2 - 3 1 - 1 1.7
16m, 13,300 48 44 2 5 2 - 2 0.70 | 1.4
16p 31,800 52 120 67 6 6's 3's 5' 2
28c 141,000 71 99 () . 7 15 6's 0 - 28 || 2: 4
37a, 18,600 30 24 5 9 0. 5, 0-10 || 0:23 - -
50e 36,000 | 16% 42 1. 18 14 || 0 30 || 3:0 Weaving shed roof.
52
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
**
Pro- Pro- : o, *
Floor Mean portion of ſportion of Number Pºiº º#. at
Room ROOf Side Of .
Area. Height. Glass Glass - -
Number. 2c, T Area to Area to Measure- Remarks,
(Sq. Ft.) (Ft.) Floor Floor ments Max. Min. Mean.
Area. Area. º
(1) (2) (3) (4) (5) (6) (7) (8) (9)
Cºlºr:#;" Jor | Per Per Per | Per | Per
" … cent. cent. cent. cent. cent. -
3c 9,000 || 36 110 () 3 16 || 7 | 2 |11 Machinery and boiler testing.
10a 5,000 | 16 () 14 8 1-6 || 0-08 || 0 5, Metal polishing, &c.
10b 5,300 | 10 0 11 8 4 6 0-10 || 17 | Brass fitting.
10c 5,300 | 1.4% 25 11 6 6 2 || 1 | 3 || 3: 6 || Brass fitting and engraving.
10h. 13,400 18% 75 13 10 9 'o 1 : 1 || 3: 6 Gauge making.
10k 9,950 32 () 45 9 15 || 1:15 | 6’ 6 Electrical engineering.
16h, 3,100 33 () 1] 6 2.7 - || 0 - 17 | 1 - 0 35
17a. 1,850 | 1.1% 0 || 13 6 3' 6 0.96 || 2: 0 || Metal fitting.
28e 11,000 || 30 100 () 7 4's 2' 4 || 3:0 33 55
50a. 3,300 13 () 19 8 1 : 5 0-04 || 0 65 | Electroplating and varnishing.
50b 2,800 13 () 20 11 2 5 || 0:40 || 1 0 | Telephone winding, &c.
50d 5,630 | 13 () 20 8 1' 7 || 0-28 || 0 9, Assembling machinery.
Class III. — Forges and
Heavy Work :
T.6b 7,580 21 5 : 5 4. 7 1.8 || 0.3, 1:1 Spring making.
16d, 13,000 || 24 24 () 7 2-0 || 0:33 || 1:1 | Steel rolling.
16k 21,200 || 33 23 6 6 3-4 || 1:7 || 2: 6 Boiler flue making.
160 38,900 65 86 35 6 12 9's — Forging.
17b 1,340 | 1.1% () 9 4. 0-25 || 0:02, 0-10 || Grinding.
28d. 99,000 | 62 100 0 11 5 : 3 1-4 || 3:4 Boiler making.
37c 12,200 54 () 20 5 --- — | 0:49 || Forging.
376, 8,260 28 2 - 5 9 6 0.4s 0-22 || 0:30 53
Class IV.-Woodworking
and Pattern - making
Shops :
16m. 11,500 30 55 36 8 4' 0 || 1:2 || 2:2
28a. 30,000 || 35 51 11 9 7 's 0 - 24 || 2 | 1
28b 17,400 || 31 - 7' 5 6 6' 3 0 21 2.5 Galleries of No. 28a.
50c 4,540 13 () 21 7 5' 4 1 - 3 - 2 - 9
FREQUENCY OF OCCURRENCE CURWEs,
Frequency of occurrence curves are appended.
These include:— - -
(a) The observations at machines such as lathes,
planing and drilling machines, &c., requiring
little close attention. :
(b) The observations at places used for benchwork
such at fitting, finishing, and other work
requiring close attention.
(c) The observations in shops where heavy work
was in progress.
(d) The observations on the floors of engineering
workshops of all classes.
2 O
1 O
O
| O
O
oº, 1% zº, sº 4%. 5% e3 =%
1 O
O
I C
O –
0.0% O.5% 1.0% 1.5% 2.0% 2.5% 5.0% a.s% to%
Daylight Factor (Percentage of Outside
Illumination).
( FIg, 11–ENGINEERING SHOPs (DAYLIGHT).
The following features in connection with the curves
should be noted:— r
Machine Work (Curve A).-The slope of this curve
to the right is gradual, indicating a large number of
observations considerably above the mid-point value of
daylight factor.
Bench Work (Curve B).-The same remark as that
made on the last curve (A) applies equally to this.
The shape of the curve, however, is less definite, and
hence the position of the mid-point is liable to some
error. Approximately 4 per cent. of the observations
lie above a daylight factor of 10 per cent., and so have
not been included in the diagram.
Heavy Work (Curve. C).--This curve is extremely
flat, indicating a wide diversity in the daylight-factors
found in workshops of this class. Here again 8 per
cent. of the observations lie above a daylight-factor
of 4 per cent, and so have not been included in the
diagram.
Floors in all Machine Shops (Curve D). This
curve, again, is very flat. Uncertainty as to the posi-
tion of the mid-point arises from the same cause as
that noted for Curve (B) above. . Approximately
15 per cent. of the observations lie above a daylight-
factor of 4 per cent. and so have not been included in
the diagram S.


APPENDICEs.
53
GENERAL ANALYSIs.
(ENGINEERING WoRKSHOPs.)
The following Table and General Analysis are deduced from the Curves in Fig. 11.
TABLE XVIII.
Percentage of Observations lying below the following
Daylight Factors:—
Below Below Below | Below Below | Below Below Below | Below
0 - 5. 1 * 0. 1 : 5. 2 ” (). 2 : 5. 3 * 0. 3 5. 4 - 0. § ()
(1) (2) (3) (4) (5) (6) (7) || (8) (9) (10)
Per Ber | Per | Per | Per | Per | Per | Per | Per
cent. cent. cent. cent. cent. cent. cent. cent. cent.
Machine work (Curve A) {- tº- - - || 16 35 52 65 75 83 89 94. 96 .
Bench work (Curve B) - º - - - | 15 31 44 54 62 69 74 || 80 85
Heavy work (Curve C) - º * * - || 31 49 63 74 82 86 90 92 -
Floors (Curve D) - º * - - - 30 46 57 67 75 80 82 85 *-
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie) are
approximately as follow —
Machine work (Curve A) sº
Bench work (Curve B) *
Heavy work (Curve C) s
Floors (Curve D) º &
Daylight Factor.
Summary of Artificial Light Observations.
Factories 3, 4, 6, 10, 16, I7, 29, 37, 50.
The total number of shops in which measurements of
artificial illumination were taken was 43. The kind of
lighting systems met with included batswing gas-burners,
ordinary upright and inverted incandescent gas, high-
pressure gas, electric glow-lamps (used both for local
and for general lighting), and arc lamps. It was
noticed that, as a rule, the same general system of
lighting prevailed throughout all the shops in each
factory. Thus in factory No. 16 general lighting was
mostly by arc lamps, while the machines, benches, and
all local workplaces were illuminated by small electric
glow-lamps. In factory No. 10 the general lighting
was by arc lamps, the local lighting by batswing gas-
burners. In three of the rooms (Nos. 10a–c), how-
ever, the general lighting was by incandescent gas,
while in room No. 10e, a combination of this with
mercury vapour lamps was employed. In this last
room, owing to lack of natural lighting, artificial
light was in use all day and the result was stated to be
satisfactory. In factory No. 17, the only system in
use consisted of batswing burners arranged so that, as
far as possible, they illuminated the work locally. In
room No. 17a, there was some attempt at general
lighting by one incandescent gas-burner, but on the
whole, as will be seen from the tables, the lighting of .
this factory was poor. In factories Nos. 28 and 37 the
general lighting was by arc lamps, the local lighting
by electric glow-lamps. In factory No. 50 all the
lighting was by electric glow-lamps. In room No. 3d
the general lighting was by high-pressure gas, the local
lighting by batswing gas-burners.
In several factories where arc lamps were used, the
iights seemed to be hung too low to give the most
satisfactory general illumination. In this way dense
black shadows were often formed, and in one instance
these were complained of. There was also one com-
plaint of glare owing to the low position of the lighting
units.
When electric glow lamps were used for local light-
ing they were often, but by no means always, efficiently
shaded. The shades used for the lamps illuminating
vices and for bench work generally were mostly of the
ordinary enamelled iron form. It is probable that in
many "cases parabolic or similar specially designed
shades would give more Satisfactory results. For
illuminating machines such as lathes, where the local
light had to be close to the work, the most satisfactory
form of shade appeared to be of a conical form
(Room No. 10m).
The illuminations are scheduled in the table, and
the grouping of the shops into the four classes adopted
for the daylight factors has been retained here. As
before, illumination of the shops in Class III. (heavy
work) was usually very general, comparatively few local
lights being provided.
The measurements on floors have been omitted in
considering the minimum and meanilluminations given
in the table, so that these include only the observa-
tions made at actual places of work. For the floor
illumination, the frequency of occurrence curve should
be consulted. -
TABLE XIX.
SUMMARY OF THE ARTIFICIAL LIGHT OBSERVATIONS IN THE ENGINEERING WORKS WHERE
MEASUREMENTS HAVE BEEN MADE.
Distance | |Illumination at Point of W ork.
Floor Area. of Chief Numbel (Foot-Candles).
Nº. isiº Mºre. Remarks.
(Sq. Ft.) E. º ments. | Max. Min. Mean.
(1) (2) (3) (4) . . . (5) (6) (7) (8)
Class I–Machine Shops :
3d 24,200 7; 5 9-5 0.70 || 4-2
4b 6,440 | 14 3 || 1:25 () • II 0.57 || One arc only ; other illumination purely
i local and by gas jets.
54 DEPARTMENTAL
COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
Distance
Floor Area. of Chief Number
Room Lighting of
Number. (Sq. H t.) | Units above Measure-
Floor (ii) ments.
(1) (2) (3) | Gł)
6b 8,200 13; 7
10d. . 42,000 26 to 40 15
10e 9,200 17% 6
10f 10,000 11; 5
10g 19,600 23 11
IOl 75,600 Various 20
10m, 7,800 12% 5
16c 11,700. 10 8
16e 8,200 35 4.
16f 15,500 16 & 35 9
16g 24,800 20 & 40 5
16] 34,000 31 6
l6m. 13,300 16 5
16p 31,800 24 & 50 6
28c 141,000 24 15
37a, 18,600 7 to 30 9
50e 36,000 11 16
Class II.-Rooms for Bench Work :
3c
10a.
|Ob
10c
10h.
10k
16h.
17a.
28e
50a
50b
500,
9,000
5,000
5,300
5,300
13,400
9,950
3,100
1,850
11,000
3,300
2,800
5,630
l
1
Class III—Forges and Heavy Work :
I6b
16d
16];
160
17b
28d.
376
376,
Class IV.- Woodworking and Pattern-making Shops :
16m.
28a.
28b
50c
7,580
13,000
21,200
38,900
1,340
99,000
12,200
8,260
11,500
30,000
17,400
4,540
11
20
T1
24 and 60
4
25
11
15
17
13
13
7
I
8
10
6
7
Illumination at Point of Work.
(Foot Candles.)
Max.
(5)
Min.
(6)
Mean.
(7)
Remarks.
(8)
6
I
i
ſº
5
:
5
0
1
I;
S
5
6 - 7
25°o
6 : 6
4 - 1
:
• 50
• 38
• 17
• 35
• 57
• 28
• 13
‘lo
• 22
08:
54
• 34
• 46
• 57
• 19
• 61
10
• 91
• 30
• 76
• 80
• 37
• 70
• 51
• 30
• 43
• 75
• 97
• 19
• 51
71
• 11
54
• 13
• 50
05
• 56
:
i
0
0
:::
0i
1
i
i()
0
i
:
i
Mercury vapour lamps.
*Local lighting very efficient.
f Local light not in use.
j. Due to local light. Average general
illumination about 0 5 foot-candles.
See remarks in Table 13, page 45, sum-
- marising daylight factors for these
I’OOIſlS.
See remarks in Table 13, page 45, sum-
marising daylight factors for these
I’OOTYl S.
Galleries to No. 28a.
FREQUENCY OF OCCURRENCE CURVES.
Frequency of occurrence curves are given in Fig. 12
Here, as before, the
division of shops has been abandoned in favour of a
division of points of observation according to the classes
for processes in engineering shops.
of work carried on at those points.
The curve for
floor illumination embodies the results obtained for all
classes of engineering shops exclusive of foundries,
and of the carpentering shops of Class IV,
The following points in connection with these curves
should be noted :—
Machine Work (Curve A).-In this curve the gradual
downward slope to the right indicates that there is no
very definite illumination which is regarded as the
best for this kind of work, and it will be seen from the
table that while about one-third (36 per cent) of the
observations lie below 1 foot-candle, there is an equal
proportion above 2: 5 foot-candles, so that the middle
one-third of the observations lie between 1 and 2.5 foot.
2 35
4. 5 6 IO
Foot-Candles.
2 & 9
O.5
1.O
1.5 2.O 2.5 3.0
Foot-Candles. . . . ;
3.5 4.O
FIG. 12.-ENGINEERING SHOPs (ARTIFICIAL LIGHT).


APPENDICES.
55
candles. Approximately 8 per cent. of the observa-
tions lie above 10 foot-candles. As these are distri-
buted somewhat widely, the upper limit being 63 foot-
candles, it was not thought desirable to decrease the
scale of the curve to the extent necessary for the
inclusion of these points. The mid-point of the curve
lies at about 1 - 5 foot-candles.
Bench Work (Curve B).-A similar deduction may
be drawn from the curve for bench work, except that,
in this instance, the observations are so distributed
that approximately one-third lie below 1:25 foot-
candles, one-third between 1 25 and 3 0 foot-candles,
while the remaining third are all above the latter
value. This distribution indicates that bench work is
allowed a higher degree of illumination than machine
work. Here, again, 6 per cent. of the observations lie
above 10 foot-candles, and have not been included in
the diagram for the same reason as before.
Heavy Work (Cwrve C).-The curve for heavy work
such as forging, spring making, rolling, &c., is some-
what indefinite owing to the limited number of obser-
vations available, but the uncertainty indicated by the
two previous curves as to the degree of adequate
illumination does not appear here to the same extent,
for over 50 per cent. of the observations lie between
0 - 75 and 1' 75 foot-candles.
Floor illumination (Curve D).-The curve for floor
illumination in all classes of machine shops indicates
that there are comparatively few observations (about
24 per cent.), which lie above 1 foot-candle, or below 0°4
foot-candles, so that an illumination between these limits
..is that most commonly met with.
GENERAL ANALYSIs (ENGINEERING SHOPs).
The following Table and General Analysis are deduced from the Curves in Fig. 12.
TABLE XX.
Percentage of Observations lying below the following values of Illumination :-
Below Below i Below Below Below | Below Below Below Below Below Below | Below
() • 25 () - 5 0 - 75 1 : () I 25 I - 5 1. 75 2 - 0 2 - 5 3 - 0 3 - 5 4 - 0
ft.c. ft.c. ft.c. ft.c. ft.c. ft.c. ft.C. ft.C. ft.C. ft.c. ft.c. ft.c.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)
T^er | Per | Per | Per | Per | Per Per | Per Per Per Per | Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Machine work (Curve A) 4 16 27 36 43 48 52 56 62 67 70 73
Bench work (Curve B) - I - 5 5 : 5, 12 21 30 39 48 54 63 71 75 81
Heavy work (Curve C) - 3 - 5 | 1.4 31 48 63 75 83 92 99 tº-mº mºs --- *
Floors (Curve D) - - 14 41 62 76 85 91 95 98 tºmº *-* * e-º-º-º-º:
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie)
- are approximately as follow :-
1 6 foot-candles.
I tº: 85 53
Machine work (Curve A) -
Bench work (Curve B) gº
1 * 0 foot-candles.
0 - 6 52
Heavy work (Curve C) -
Floors (Curve D) - tºº
P.–FOUNDRIES. --
Summary of Daylight Observations.
Factories 3, 4, 5, 6, 7, 10, 11, 15, 16, 17, 37.
Of the 18 foundries investigated, 12 had at least
90 per cent. of the total window area as roof light.
Six had both side and roof lighting, while only one had
less than half the total glass area as roof light.
Class (1) Roof-lighted Foundries.—The roof glass
area expressed as a percentage of the floor area varied
from 12 to 120 per cent. In the latter case where the
roof was entirely of glass the daylight factor on the
floor varied from 17 to 32 per cent. in one foundry
(No. 3a), and from 5 to 10 per cent. in the other
(No. 3b). The lower figure in the latter case was
probably due to “ageing ” of the glass, as the former
was obtained in quite a new building with all walls, &c.
of a light colour. In these cases the natural lighting
was probably as good as could be devised. -
Class (2) Roof. and Side-lighted Foundries.—The
roof glass expressed as a percentage of the floor area
varied from 3% to 37 per cent. while the total glass area.
varied from 8 to 50 per cent. Of the floor area.
In one foundry (No. 4a) the glass in the side walls
was replaced by Slatting.
The effect of dirty glass was very noticeable in both
classes of foundries and was well shown by the contrast
between foundries Nos. 4a and 7a. In both of these
the mean height was approximately the same while the
advantage as to glass area lay with No. 4a, in which
case also, some assistance was obtained from side
lights. The glass, however, was so dirty that the
mean daylight factor was only 0°38 per cent. compared
with 5.8 per cent. for room No. 7a, where the glass
was clean.
In considering the daylight factors entered in the
following table, none of the observations on benches or
machines in foundries have been included, but only
those at floors or other places of moulding or casting.
TABLE XXI.
SUMMARY OF THE DAYLIGHT OBSERVATIONS IN Foun DRIEs where, MEASUREMENTS HAVE BEEN MADE.
Propor- g g
. Of Propor- Number Daylight Factor.
Floor Mean tion of
Room tº ROOf . |Side Glass Of
Numbe Area Height. Aºt, Area to Measure- State of Glass. Remarks.
* (sq. F.) (Ft.) | *...* | Floor c. Max. | Min. Mean.
Area Area. ments.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Per Per Per | Per | Per
| Cent. Cent. cent. cent. cent.
3a 20,800 27 120 0 3 32 17 25 Clean A very new foundry.
3b 40,800 34 80 () 5 9's 4's 7' 2 5 3
5a 37,000 | 18 12 0 10 7'o 0.09: 1-9 Dirty
56
DEPARTMENTAL committee oN LIGHTING IN FACTORIES AND workSHOPS:
Propor- . - ~ . . . . - - -
Floor . Mean tioº of | º: Number Daylight F actor.
Ya. - Roof ..." -
f s ---. rr. . . . . . ." |Side Glass of
Area Height. Glass ‘’’. . . . º ºg º –
* - , , - Area to - | State of Glass. Remarks.
Number. Area to Measure- - - - - . - .
- * | (SC. Ft. Ft.) Iri. Floor || | Max. | Min. x in , - -
(Sq. Ft.) | ( º r * A. Iment.S. ax in. | Mean.
(b | 9 || 0 || 0 || 0 || 0 || @ Go || 0 (10)
. Der Per Per | Per | Per
- - Cent. Cent. - Cent. Cent. Cent. -- -
5b 18,600 || 23 39 0 8 5's 2' 4 || 4 - 4 || Rather dirty | Newer than No. 5a
6a, 34,500 39 76 2 - 5 10 3 : 6 0-13 1.7 * --
7a || 33,400 || 37 41. 1 - 5 8. 12 || 2 | 4 || 5's Clean
15a. 2,950 20 31 () 5 || 1:1 0 - 7s || 0 8s , Windows cleaned
7 . . . . . every few months.
15b ,800 | 1.4 20 () 6 4'o 2 : 1 || 2: 6 35 - 25
i5c 23,900 17 28 () 9 2-1 || 0:46 || 1:1 . - 55
H6a 28,300 46 22 0 9 || 3 g || 0:4s | 1.8
164 25,800 53 | 20 0 11 1:2 || 0-3s 0-7 | Dirty
37 54,700 35' 34 3 11 2 : 1 || 0-30 || 0 - 7s »
4a. 19,200 || 42 50 10 8 || 0:56 || 0:18 0-3s Very dirty
10m. 49,500 - || 36 || 30 7 9 3 : 3 || 0 30 1' 9 Dirty
100 27,100 | 56 s 37 12 7 5’ 6 || 1 ||6 || 3:0
11a || 3,170 | 16% | 11 11 4 1.8 || 0:40 || 0-9, 55
17c 2,700 20 3.5 6 5 I 2 0 - 28 0-6s -
17d 6,850 20 5 : 5 3 6 1-0 || 0–3, 0:5s
FREQUENCY of OccuRRENCE CURVEs.
Frequency of occurrence curves are appended.
These include :- - . -
(a) The observations at the floors of foundries with
- - -- roof lighting (the few observations on ma-
chines, &c. have been omitted but are very
similarly distributed). - -
(b) Those in foundries with combined roof- and
side-lighting. - .
The following features in connection with the
curves should be noted:— ; : -
Roof lighting (Curve A).-The slope of this curve to
the right is fairly gradual, indicating a good proportion
of observations at the higher daylight factors. Six
per cent. of the observations lie above a daylight
factor of 10 per cent. and have not been included in the
diagram.
combined Roof. and side-lighting (Curve B)—This .
curve falls away rapidly to the right indicating that
the higher values of daylight factor are not represented,
*:
g”
in fact 75 per cent. of the observations lie below a
daylight factor of 1 per cent.
3 O
I 5
1 o H
5
o
I 5
H. O.
O
1%
2% sº. 4%. 5% e?, zº, sº, 9%, 10%
Daylight Factor (Percentage of Outside
Illumination).
FIG. 13.−FounIDRIES (DAYLIGHT).
GENERAL ANALYSIs (FoundRIES).
: The following Table and General Analysis are deduced from the Curves in Fig. 13.
TABLE XXII.
- Percentage of Observations lying below the following Daylight Factors:—
| Below Below Below || Below | Below | Below Below Below Below Below
0 - 5, 1-0. 1 : 5, 2 : 0. 2 : 5. 3 * 0. 3 : 5. 4 * 0. 4 : 5. 5' 0.
(1) (2) (3) | (4) (5) (6) (7) (8) (9) (10) (11)
Per - Per | Per | Per || Per Per | Per | Per Per Per
- Cent. Cent. Cent. Cent. Cent. Cent. Cent. Cent. Cent. Cent.
Roof, lighting (Curve A) - gº - 15 36 54 65 72 77 80 83 || 86 88
Combined roof- and side-lighting 44 75 S3 88 93 96 97 98 99 99
(Curve B.) -
*3
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie) are
approximately as follow :-
Roof-lighting (Curve A) tº
Combined roof- and side-lighting (Curve B) "e , - . - 0.6 ,
Daylight Factor.
- 1.4 per cent,
& - * !


APPENDICEs.
57
Summary of Artificial Light Observations.
Factories 3, 4, 5, 6, 7, 10, 11, 15, 16, 17, 37.
Of the 18 foundries investigated, the chief system
of lighting was by arc lamps in eight cases, by gas
(high-pressure or ordinary incandescent) in three, by
electric glow lamps in four, and by batswing burners
in three cases. Seven of the foundries had local light-
ing by gas and electric light in addition to the main
system. In many foundries the lighting seemed
generally sufficient, but it appeared particularly bad in
in those foundries lit mainly by batswing burners,
(Nos. 11a, 17c, 17d), some parts of which were clearly
dangerous. The chief disadvantage of lighting by
isolated powerful sources, especially in foundries with
low roofs, is the dense black shadow cast by every
object in the neighbourhood of a lamp. This makes it
extremely hard to see the nature of the ground which
happens to be in such a shadow, and it has been stated
that accidents arise from this cause. It is particularly
necessary that the passages and gangways of foundries
should be well illuminated, as otherwise there is always
some likelihood of treading upon hot metal which has
been spilt in transit but is no longer visible by its own
incandescence.
In considering the illuminations entered in the
following table, none of the observations on benches or
machines in foundries have been included, but only
those at floors or other places of moulding or casting.
TABLE XXIII.
SUMMARY OF THE ARTIFICIAL LIGHT OBSERVATIONS IN THE FoundRIEs whºRE MEASUREMENTS
FIAVE BEEN MADE. -
Dº: Number of Illumination at Point of
Room Floor Area. 9%. Sºº Work (Foot-Candles). *
Lighting Measure- - *
Number. (Sq. Ft.) | Units above , -- Remarks.
l Floor. (Fij ments. Max. Min. | Mean.
(1) (2) (3) (4) (5) (6) (7)
3a. 20,800 13 3 0 - 74, 0 - 42 0 58
3b 40,800 20 5 4 - 2 0. 53 2:30 | A few local gas jets.
4a 19,200 25 8 () - 65 0.03 0-30 | A few local lights.
5a. 37,000 Various 10 1 - 05 0 - 06 0:37
5b 18,600 Various 6 1 : 10 () - 04. 0 50
6a, 34,500 Various 10 1-8s 0 - 50 0 '86
7a. 33,400 16 8 1:7; 0 - 11 0 74
10m. 49,500 10; 9 () - 82 0 - 30 0. 54 || Complaint from worker.
100 27,100 10 7 (): 34 0 - 20 0 25
11a. 3,170 13 4. 0 - 26 (). I2 0 - 19 | Very unsatisfactory lighting,
15a. 2,950 5#. 5 () - 59 () 11. 0 - 26
15b 7,800 8 6 () . 78 (). T6 0 44
15c 23,900 6 9 1 30 (). 13 0 48
16a, 28,300 20 9 3. 8 () - 18 1 : 00 Some local electric lamps.
164 25,800 42 12 () - 87 0 075 || 0 41 | A few local lights.
17c 2,700 Various 4. 0 - 56 (?. 07 0 24 | Very unsatisfactory lighting
17d. 6,850 6 0.86 |<0.02 0 - 18 5 3 92 92
37b 54,700 Various 12 2.80 0 - 02 1 - 05
FREQUENCY OF OCCURRENCE CURVE.
A frequency of occurrence curve for the artificial
illumination of the floors of foundries is given in Fig. 14.
The slope of this curve to the right is fairly gradual,
indicating that the mid-point value of illumination is
often considerably exceeded.
cent. Of the observations lie above 2 foot-candles, and
so have not been included in the diagram.
The following Table and General Analysis are deduced from the Curve in Fig. 14.
Approximately 4 per
1.<}
O.2 G.<+ O. 6 O. 8 1.O I.2
Foot-Candles.
1.6 l. & 2.O
FIG. 14.—FOUNDRIES (ARTIFICIAL LIGHT).
GENERAL ANALYSIS (FOUNDRIES).
TABLE XXIV.
Percentage of Observations lying below the following values of Illumination :-
Below Below Below Below Below Below Below Below
0 - 25 0 - 5 0 - 75 1 - 0 1 - 25 I 5 1 - 75 2 - 0
ft.-c. ... ft.-C, ft.-c. ft.-c. ft.-C. ft.-C. ft.-c. ft.-c.
# * }:
wº-> (1) (2) (3) . (4) (5) (6) (7) (8) (9)
Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent. Per cent.
Eoundry floors - sº sº 36 63 76 85 90 93 95 96
The mid-point of the curve (i.e., the point above and below which equal numbers of observations lie) is
approximately at 0°4 foot-candles,

58
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND workshops:
III.-MAKING UP OF CLOTHING AND SIMILAR WORK.
Summary of Daylight Observations.
Factories 8, 9, 13, 21, 22, 23, 24, 29, 30, 33, 34, 44, 46, 47, 48, 51, 52, 53, 54, 55, 56.
Daylight measurements were made in all the 37
clothing workrooms visited. Of these, seven were roof
lighted (i.e., had at least 75 per cent. of their total glass
area situated in the roof), 16 were lighted exclusively
by side windows, while the remainder had a combination
of both systems. The inferiority of a system of light-
ing exclusively by side windows as compared with one
including some roof glass was very noticeable. This
will be seen from the table. The windows, especially
those at the side, were, in general, clean, but those in
the roof did not seem to have received the same
attention. The difference produced by the cleaning of
the roof glass is seen from a comparison of Rooms 54a
and 55a in the table. The roof glass area was the
same in both these rooms, but in the second, which had
clean glass, the mean daylight factor was nearly double
that found in the first, the glass of which was very
dirty. In Factory No. 30, with six or seven floors,
the building was in the form of a square with a large
rectangular shaft or well, and light was admitted to
the rooms from this central shaft as well as by windows
out the outside walls. The result of this was a more
even distribution of light, especially in the case of the
upper floors.
In the tables given below, the rooms have been
divided into three classes :—
I. Those used for sewing, either by hand or by
machine, on woollen or other cloth, generally
of a dark colour. sº
II. Those used for the less fine processes of cutting
Out or pressing.
III. Those in which the work was with white linen.
Further, the rooms in each class have been arranged
in three groups, according as the lighting was ;-
(a) By roof windows. -
(b) By combined roof and side lighting.
(c) By side windows alone. -
The measurements on floors have been omitted in
considering the minimum and mean illuminations given
in the tables, so that these include only those obser-
vations made at actual places of work. For the floor
illumination the frequency of occurrence curve should
be consulted.
TABLE XXV.
SUMMARY OF THE DAYLIGHT OBSERVATIONS IN THE CLOTHING WORKSHOPS WHERE MEASUREMENTS
HAVE BEEN MADE.
Pro- Pro- . Daylight Factor at
Floor Mean pº Of º of sº Point of Work.
* * ** iorhi. Glass Glass O º
Room Type of Lighting. Ales Height. Area to Area to Measure- Remarks.
Number. (Sq.Ft.) (Ft.) Floor Floor Max. Min. Mean.
Area. Arca. ments.
(1) (2) (3) (4) (5) |* (6) (7) | (8) (9) (10)
º * | T^er | Per
Class I-Sewing on Colowred Cloths: *: : º: cent. cent.
29b (a) Roof-lighting 1,320 | 10 30 1 8 3 : 3 || 0 70 || 1 | 7 || Roof sloping al-
- | most to floor on
47b 25 2 3 4,760 | 16 50 11 10 6's 1 - 9 || 3's • One side.
47c 33 55 3,170 15 52 12 6 5.6 || 2:0 3'4
51a. 33 , 267; 11 47 3 6 1-2 || 0:46 || 0 90
8. (b) Combined 1946 is 14 7' 5 6 5' 0 || 3: 3 || 3’s
! roof- and }
side-lighting
33b 5 3 33 3,400 13% 8 7' 5 8 2.8 || 0.3s | 1 : 5
34b 3 3 55 2,360 10% 17 7 14 12 1.6 5 'o
46b 5 3 ,, . 2,700 14 15 14 9 10 1' 7 || 4's,
46d. 53 33 1,770 13 9 - 5 || 11 7 4's 1 5 || 3'4
47a, 55 > 2,200 22 26 15 8 1 : 1 || 0:40 || 0 6s
48c 53 33 2,060 | 12 13 14 8 6's 1' 4 || 3's
520. 5 5 ... 247 | 10 16 7' 5 5 1 - 6 || 0.3s 1 - 0
54a, 3.3 ,, . 247 14 32 24. 6 1. 7 || 0-11 || 0 90 || Roof glass very
| dirty.
55a 33 3 9 247 14 32 10 4. 2 : 0 | 1.4 || 1 - 7
56a. 35 5 § 247 14 20 14 5 0-9s | 0: 16 || 0-5, 35 35
294, 55 5 3 1,890 } 2 - 5 12 9 4.0 || 0:12 | 1.6 | Very little roof-
lighting.
48a. 33 35 5,960 11 2 11 I0 5' 2 || 0:44 || 2:2 5 3 35
9a | (c) Side-lighting 530 8 0 17 5 9 : o 0.8s 3-4
13a. 3 3 35 3,570 10% 0 13 I2 2.7 || 0.3, 1:1
13c 33 55 3,470 11 () 15 9 3. , || 0:7, 1.5
30a, 3 5 3 y 4,700 12 () 13 15 4's 0°12 || 1 | 1 | Lighting by cen-
tral well.
30b 35 55 4,700 12 () 7' 5 11 4.0 || 0:29 || 1:1 35 35
33a 5 3 55 2,800 # 0 15 9 4' 0 || 0 29 | 1.6
34a. 5 3 52 2,890 10 0 13 8 3's 0-17 | 1.8
44b 5 3 52 870 13 0 35 7 5. 0-25 | 1.8
44c 3 3 52 870 11, () 35 6 3's 0 '92 || 2:3
46a. * 3 33 2,900 10% O 23 9 2. 7 || 0 - 11 || 0-7,
46c 55 55 1,580 10% 0 13 7 1-6 || 0-17 | 0-80
48b 3.3 53 1,580 11% () 33 8 4' 4 || 0-80 || 2:3
53a. 33 y5 178 9 () 6 5 0 '92 || 0 10 || 0:4,

APPENDICES.
59
Pro- Pro- Daylight Factor at :
* portion of portion of Number Point of Work.
Room Floor Mean *.*.*. f
N Type of Lighting. Area Height. Glass Glass O Remarks.
umber. 7t Area to Area to Measure-
(Sq.Ft.) (Ft.) Floor | Floor tS Max. | Min. Mean.
Area. Area. IſleIltjS.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
º e Per Per Per | Per | Per
Class II—Cutting and Pressing : cent. cent. cent. cent. cent.
13b Side-lighting - || 4,000 | 10; 0 4. | 5 1 6 || 0:44 || 1:1
44a | , , 840 12% | 0 () 5 | 1.4 || 0:12 || 0: 50
Class III.-Sewing on White Line; : - - |
22a || Roof-lighting - | 1,550 | 1.4% 35 0 8 4's 2:1 3'2
23a. 35 3 5 1,200 | 1.4% 45 0 7 10 4'o 6' 6
24b , ,, 7,500 18 25 3.5 li | 3 || 4, 13
21b Combined roof- 880 | 12% 7' 5 8.5 8 2- 9 || 1 - 0 || 2:2
and side-
lighting.
21a || Side-lighting - | 1,100 | 9% () II. | 6 1.9 || 0-19 || 0-7,
FREQUENCY OF OCCURRENCE CURVES
Frequency of occurrence curves are given in Fig. 13.
The observations have been divided into :—
(a) Those at places where ordinary dark coloured
, cloth was being sewn. l -
(b) Those on cutting and ironing tables, &c.
(c) Those in workshops where sewing or hem-
stitching on white linen was in progress.
(d) All the observations on floors.
&O
*O
63 O
5 O
<+ O
350
2 O
R O
O
LO
O
# O.
ºf O
2O
I O
O >
O% 1%. 2% º 4%. 5%, 6% 7% sº, 9%, 10%
Daylight Factor (Percentage of Outside Illumination).
FIG. 15.-CLOTHING FACTORIEs (DAYLIGHT).
The following features in connection with the curves
should be noted :—
Sewing on Coloured Cloths (Curve A).-The slope of
this curve will be seen to be gradual from a daylight
factor of 0° 5 per cent. up to 6 per cent. or 8 per cent.
The observations plotted include those taken in both
side- and roof-lighted premises, and this fact accounts
for the wide diversity of the results. The high values
of the curve at the lowest daylight factors must be
taken as indicating a considerable amount of indif.
ferent lighting Owing to the prevalence of the use of
side-lighted rooms for this work. It must be remem-
bered that a work-bench under a window will have a day-
light factor of the Order of 2 per cent. It would there-
fore appear that much work requiring good lighting is
carried on away from windows, where often the illumi-
nation would be indifferent. -
Cutting and Pressing (Curve B).-The remarks
made on Curve (A) above apply also to this curve.
Sewing on White Linen (Curve C).-This curve is
extremely flat, indicating that there is no very definite
tendency towards any One daylight factor in the work-
shops of this class. The mid-point value, however, is
well over 3 per cent. It will be noticed from the table
that three out of the five workshops in this class were
well provided with roof lights, but the fact that only a
limited number of factories are considered and that
they were all in one locality, prevents the drawing of
conclusions from this curve for the industry generally.
Approximately 16 per cent. of the observations lie
above a daylight factor of 10 per cent., and so have
not been included in the diagram.
Floors (Cwrve D).--Here, again, the curve to the
right is very extended, giving the same conclusions as
those noted for Curves (A) and (B) above.
GENERAL ANALYSIs (CLOTHING WoRKRooms).
The following Table and General Analysis are deduced from the Curves in Fig. 15.
TABLE XXVI.
Percentage of Observations lying below the following Daylight Factors:–
-*- Below | Below | Below | Below Below Below | Below Below | Below | Below •.
() 5. 1 * 0. 1 : 5. 2 : 0. 2 : 5. 3 - 0. 3 - 5. 4 * 0. 4 5. 5 ().
(1) (2) (3) (4) (5) (6) (7) | (8) (9) (10) (11)
Per | Per | Per - Per | Per | Per | Per | Per | Per Per
cent. cent. cent. cent. cent. cent. cent. cent. cent. cent.
Sewing on Coloured Cloths (Curve A) - | 15 33 48 59 | 68 75 80 84 88 90
Cutting and Pressing (Curve B) - - 22 42 57 68 77 85 90 95 98 99
Sewing on White Linen (Curve C) - I 5 5 11 21 33 44 54 62 68 74
Floors (Curve D) - - -- - || 31 46 56 64 71 76 8]. 85 88 91
**~~~~~
a 30030

60
DEPARTMENTAL committee ON LIGHTING IN FACTORIES AND WORKSHOPS:
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie
are approximately as follow —
Sewing on Coloured Cloths (Curve A)
Cutting and Pressing (Curve B)
Sewing on White Linen (Curve C).
Eloors (Curve D) gº -
Daylight Factor.
1.6 per cent.
33 33
*= - -
55 35
:
:
& sº -
3 * * 3
Summary of Artificial Light Observations. -
Factories 8, 9, 13, 21, 22, 23, 24, 29, 30, 33, 34, 44, 46, 47, 48, 51, 52, 53, 54, 55, 56.
The total number of clothing workshops and sewing
rooms in which measurements were made was 37. The
lighting systems met with included batswing gas
burners, incandescent mantles both upright and in-
verted, electric glow lamps, and indirect lighting by
inverted arcs. As good examples of each of these
systems, factories 9, 55, 34, and 30 respectively may
be quoted. It will be seen from the table that good
results may be obtained from any of the above systems
of lighting except the first. In shops Nos. 8a, 9a, and
29b, tailoring work was being carried on at floor level,
while in all other cases it was at tables approximately
2 ft. 4 ims. above the floor level.
With sewing machines the light sources were
generally placed several feet away from the point of
work, one source often serving to illuminate several
machines. In only two factories was any attempt
made at systematic localised lighting. In One of these,
No. 33, a small electric glow lamp in a metallic
reflector was fixed to each machine close to the work
so that the light was directed almost entirely on to
the needle of the machine or its immediate neighbour-
hood. In factory No. 34 an electric lamp with enamel
shell shade was provided for each machine on an
adjustable arm. In only one room, No. 34a, were deep
metallic reflectors fitted so as effectively to screen the
lamps, which, in all other cases were either unshaded or
fitted with opal or enamel shades of the ordinary
shallow comical shape. The uncomfortable and glaring
effect of such an arrangement of lamps has already
been noticed in the summary
tion of Weaving Sheds, p. 44.
In the tables given below, the rooms have been
divided into three classes:— r
O]] the Artificial Illumina-
I. Those used for sewing, either by hand or
machine, on woollen or other cloth, generally
of a dark colour. * -
II. Those used for the less fine processes of
- cutting out or pressing,
III. Those in which the work was with white linen.
A lower illumination is sufficient in rooms of
Class III. (in which the coefficient of reflection of the
material is about 90 per cent.) than that required for
work on the darker materials used in the shops of
Class I. (coefficient of reflection from about 5 to 20 per
cent.).
The measurements on floors have been omitted in
considering the minimum and mean illuminations given
in the tables, so that these include only those observa-
tions made at actual places of work. For the floor
illumination the frequency of occurrence curve should
be consulted. It will be seen, both from a comparison
of Classes I. and II. in the table, and from the curves,
that a lower illumination was, in general, provided for
cutting or pressing than for sewing. This may be due
to the greater fineness of the latter work, or to the
large area required to be illuminated in the case of a
cutting-out table as compared with the very localised
lighting required for a sewing machine.
TABLE XXVII.
SUMMARY OF THE ARTIFICIAL TIGHT OBSERVATIONS IN THE CLOTHING WoRKSHOPs whº RE
- MEASUREMENTS HAVE BEEN MADE.
- Illumination at Point of
" – r Distance of Number Work.
Room Floor Area. º º of (Foot-Candles.) -
: - InitS above - p : * *
Number. (Sq. Ft.) Floor. * Remarks.
. . . . (Ft.) - Max Min. Mean.
(1) (2) (3) (4) (5) (6) (7)
Class I.-Sewing on Coloured Materials :
8a, , , 1,940 6%. , . . . 6. , 6 - 2 1' 30 3' 6 || Work at floor level.
9a, 530 2} 5 4 : 6 (): 40 1 ‘90 2 3 33
13a, 3,570 5 12 6 : 6 1' 35 4 - 7
13c 3,470 4% 9 1 l; 0 - 54 0 76
290, 1,890 5 and 6% 9 6 - 8 1' 40 3 0.
29b 1,320 Various 8 6 - 5 1 : 10 2' 60 || Work at floor level.
30a, 4,700 I0 15 15's | 1:30 8' 0 |
30b 4,700. 10 11 13'0 2' 60 6'8
33a 2,800 8 9 22'o 4 - 9 14' 5 Very efficient local ſighting.
33b 3,400 6 6 8 . () || 0 - 64. 3 - 0 .. - ~
34a. 2,890 4 8 13 'o 1.6, 5' 6
34b 2,360 4 14 19 'o 2. 70 9.7.
44b 870 4. 7 9 - 5 2 : 20 5 : 3
44c 870 5 6 5.9 || 2: 6. 4 3
46a, 2,900 5 9 4 - 2 1 - 4 2 : 9
46b 2,700 5 9 5-2 1:7; 3 : 3
46c 1,580 5 7 6 - 8 () . 72 3' 4
46d. 1,770 5 7. 4 - 1 1' 95 2 '85
47a 2,200 5 to 7 8 4 - 9 (): 57 2 : 40
47b 4,760 5 10 7.3 1 60 3 : 6
47c 3,170 4 to 6 6 6 : 3 1 : 10 3 : 6
48a. 5,96ſ) 3% to 5; 10 6 - 2 1 : 15 2.7,
48b 1,580 4. 8. 3 - 3 0 - 60 2 : 00
2,060 4. 7 2-9, 1 - 0, 2 : 2,

4Sc
APPENDICES. 6i
- Illumination at Point of
Distance of Number Work.
Room Floor Area. Chief Lighting Of (Foot-Candles.)
- Units above Measure- -------- Remarks.
Number, (Sq. Ft.) Floor. mentS.
(Ft.) Max. Miſl. Mean.
(1) (2) (3) (4) (5) (6) (7)
51a. 267 5% 6 5:1 1:60 3.2
52a. 247 5 5 | 2. 80 1. 25 1. 90
53a. 178 6 5 3 - 9 2: 3, 3.2
54a 247 8 6 # 5 - 8 1 - 70 4 3
55a. 247 Warious 4. 10's 5 : 5 7.5
56a 247 2 3 5 5 : {} 2 : 0, 3 - 2
;
|
Class II.-Cutting-out, &c. : t -
13b 4,000 5% 5 4 - 9 2 : 05 3 - 9
440. 840 7 5 | 19, 1.05 1'45
Class III—Sewing on White Linen -
21a. 1,100 4 5 24, 1-6, 2-1,
21b 880 4% 8 7. () 4-2 5-3
22a 1,550 6# 8 2:5, 1-5, 3-0.
23a. 1,200 6# 7 | 4:3 1 - 0, 2 : 1s
24b 7,560 5 11 7.3 3. () | 5' 2
|
FREQUENCY OF OCCURRENCE CURVES.
Frequency of occurrence curves are appended.
These include:—
(a) All observations made at places where ordinary
dark coloured cloth was being sewn, either
by machine or by hand.
24 * * I O
Eoot-Candles.
2O
1 O
O
O.O
O.5 1.5 2.0
- 2.5 3.Q
Foot-Candles.
1.0 .
FIG. 16.-CLOTHING WORKSHOPS (ARTIFICIAL
LIGHT).
3.5 4,O
(b) All other tailoring processes, such as cutting,
pressing and ironing, &c.
(c) The observations in the five factories visited
where sewing or hemstitching on white linen
was In progress.
(d) All the observations on floors.
The following features in connection with the
curves should be noted:—
Sewing on Coloured Materials (Curve A). The
slope of this curve to the right is exceptionally
gradual, showing that a considerable number of the
observations exceed the mid-point value by a large
amount. About 10 per cent. of the observations lie
above 10 foot-candles and so have not been included
in the diagram.
Cutting and Pressing (Curve B).-The peak of this
curve is more marked, and the slope to the right less
gradual than is the case with Curve (A). Both facts
indicate that the tendency is towards a considerably
lower value of illumination for these processes than
for sewing.
Sewing on White Linen (Curve C).-The mid-point
of the curve lies well below that for sewing on the
darker coloured woollen cloths (Curve A), thus indi-
Cating a tendency to provide less illumination for work
On materials with high coefficients of reflection.
Floors (Curve D).--The greater part of this curve
lies below 1.5 foot-candles, while the mid-point
approximately coincides with the peak of the curve.
GENERAL ANALYSIS. (CLOTHING WoRKSHOPs.)
The following Table and General Analysis are deduced from the Curves in Fig. 16.
TABLE XXVIII.
Percentage of Observations lying below the following values of Illumination.
Below Below Below Below Below | Below Below | Below Below | Below Below Below
**-tº-sº (): 25 0 - 5 () - 75 I () 1.5 2 : 0 2 - 5 3 - 0 3 - 5 4 - 0 4 - 5 5 - 0
ft.-c. ft-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c. ft.-c.
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13)
Per | Per | Per | Per | Per | Per | Per | Per | Per Per | Per | Per
Cent. Cent. Cent. Cent. Cent. Cent. Cent, Cent. Cent, Cent. Cent. Cent.
Sewing on coloured ma- || – I. 5 6 - 5 13 22 31 40 48 56 62 67
terials (Curve A). - - |
Cutting º pressing || – 0 & — 10 31 49 60 67 73 75 80 84
Curve B). -- | -
sº on white linen | – || 0 — 3 12 31 49 60 | 68 75 80 | 85
Curve C).
rº (Curve D) - - 10 25 42 59 85 96 99 *s- a- gººm- e- *
a 90030 G


DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
The mid-points of the curves (i.e., the points above and below which equal numbers of observations lie)
are approximately as follow :-
Sewing on coloured materials (Curve A) - -- -
Cutting and pressing (Curve B) -
Sewing on white linen (Curve C) -
Floors (Curve D) - ſº s
3:6 foot-candles.
2 : 0
5 5
º º - 2 - 5 5 3
tº- - O - 85
5 3
IV.-MISCELLANEOUS INDUSTRIES.
Summary of Daylight Observations.
Factories 3, 31, 32, 42, 43, 45, 49.
The processes carried on in 18 of the rooms visited
cannot be classed under either of the three chief
industries, and so have been placed here in a section
by themselves, the table summarising the daylight
factors giving also the various processes carried on in
the different rooms. No attempt was made to obtain
for any of these processes data sufficiently numerous
to give a reliable indication of the probable state of
illumination existing generally in places where such
processes were carried on. The results are useful,
however, as showing the daylight factors existing in
the different classes of buildings concerned and are
therefore reproduced herewith. The rooms referred
to included several printing rooms, both lithographic
and letterpress, and several rooms used for the manu-
facture of boxes and the making and packing of
chocolates. These two classes of rooms, each repre-
sented by six examples, have been placed in separate
groups in the table.
It is to be noticed that in Factory No. 42 the rooms
were One above another in the same block, and generally
identical in plan. Many of the observations in Rooms
Nos. 42c, d, e, were taken in places approximately
vertically above one another, and the improvement in
the daylight factor in travelling upwards from Room
No. 42c (first floor) to Room, No. 42e (third floor) was
very marked. The observations in the printing rooms
were taken both on the composing frames and on the
presses. Room No. 31a was used for cutting out,
stitching and packing muslim bags. It was below
Rooms Nos. 31b and 31C (see Summary on Spinning
Mills, p. 41 above) in which the bags were knitted.
Room No. 43a was used for all stages in the manu-
facture of Christmas cards, from colour printing by
hand to the tying and packing, while Room No. 43b
was used for the colouring of prints by hand. It will
be seen from the table that both these rooms were well
provided with daylight.
Room 18E. was used for “burling,” or the removal
of Small knots or lumps from cloth. It is a process of
great finemess and requires a high degree of illumina-
tion. The frames were placed near the windows, and
it will be seen that an average daylight factor of 5 per
cent, was provided on the cloth.
TABLE XXIX.
SUMMARY OF THE DAYLIGHT OBSERVATIONS IN SOME UNCLASSIFIED FACTORIES IN WHICH
MEASUREMENTS HAVE BEEN MADE.
Propor- | Propor-
tion of tion of Number Daylight Factor at
Room Floor Mean ROOf Side Of Point of Work. *
Industry. Area. | Height. Glass Glass Remarks
Area to Area to Measure- º
Number. (Sq. Fi.) | (Ft.) | Floor | Floor º
• -º- ve & Area. Area. ments. | Max. Min. | Mean,
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
Per Ter Per | Per | Per
cent. cent. cent. cent. cent.
3e Drawing office - 6,100 | 12 0 36 2 2 - 5 || 1 - 5 -"
31a | Cotton bag 2,200 # () 5 7 0. 53 || 0:010 || 0 13. Few windows,
making. - and those
very dirty.
32a | Tapestry - º 5,120 | 1.7% 46 I 8 7' 4 || 2: 9 5's
43a Xmas card print- 4,950 27 41 5 11 12. 0 - 18 5's
ing, tying, &c.
43b | Print colouring 1,080 15 () 25 8 4's 0:8, 2 9
43c | Printing - sº 1,610 || 10 () 14 7 0-3 || 0-05 || 0: 16 | Letterpress.
45a 2 3 - sº- 1,360 20 () 13 8 2:2 || 0 | 3 || 1 | 3 || Chiefly letter-
I'êSS.
49a, 3 3 - - || 13,500 | 12 () 8 12 1 4 || 0:00, 0:28 Aºi. light
- used in day-
time.
49b 5 5 - e 8,100 | 16 49 () 8 3' 6 || 1 | 9 || 2:5 Lithograph.
496, 35 - - 10,100 16 47 6 7 3.0 || 0 | 7 | 1.7
49c | Printing and | 19,300 11 () 12 18 17 | 0'00s 0'3, Artificial light
box-making. used in day-
time.
49e | BOX-making - 7,600 | 15 18 17 13 6'0 | 0 - 13 || 3:4
42a | No observations -sº -sºs --> * *= *s-s -* — Basement.
42b | Chocolate 1,800 14 () 12 7 0. 5, 0-09 || 0-3,
making and | These rooms
packing. Were Orle
42c | Cocoa packing - 4,690 13 0 I2 9 0 '98 || 0 005 || 0 3, above
42d Chocolate pack- 4,690 12 () 7 10 1-2 || 0' 020 || 0 60 another in
Ing. this order.
42e 2 3 tº 4,690 | 12 0 9 1.T. 3'o 0.015 || 0 90
18C Burling - tº 7,700 | 1.5% 29 12 9 12. 1-1 || 5 'o tº-
APPEN DICES.
3
Summary of Artificial Light Observations.
Factories 3, 31, 32, 42, 43, 45, 49.
In the 17 unclassified rooms the systems of lighting
met with included batswing gas burners, inverted gas
mantles, and electric incandescent lamps. The lighting
in room No. 3e was semi-indirect and was stated to
give very satisfactory results.
TABLE XXX.
SUMMARY OF ARTIFICIAL LIGHT OBSERVATIONS IN some UNCLASSIFIED FACTORIES IN WHICH
MEASUREMENTS HAVE BEEN MADE.
Height ~~ 3 - , , 4-, 2-,-- ~ 1. TX.- :
| Floor of Chief Numbe illuminº Point of
Room Lighting Number H' º
Industry. Area. Units Of (Foot-Candles.) -
Numbel. above | Measure- Remarks.
. (Sq. Ft.) Floor, Inents.
| (Ft.) Max, Min. Mean.
(1) (2) (3) (4) |_(5) (6) (7) (8)
3e Drawing office - 6,100 9 2 5 : 5 3. 7 *-
31a | Cotton bag making - 2,200 6; 6 () - 59 0-05 || 0 |25 | Semi-indirect light.
32a | Tapestry - - 5,120 | 12% 8 12' 0 0.70 || 3-1 83
43a Xmas card printing, 4,950 6 11 16:0 0 - 40 8-2
tying, &c. :
43b Print colouring tº- 1,080 4. 8 14' 5 4' 4 8° 4
43c | Printing - wº - 1,610 | Various 7 10's 1.90 7' 0 Letterpress.
45a. 33 " - | 1,360 ,, 9 3-5 0-80 i-6, Chiefly ietterpress.
49a 33 - - 13,500 9 12 5' S 0. 54 2' 6,
49b 5 5 - - 8,100 10 8 8 - 1 0 - 94 || 3: 4 Lithograph.
49d. 33 - º 10,100 10 7 1 : 50 0 67 || 0 - 93 -
49c 5 5 - rººt - 19,300 | Various 18 9 . () () - 39 2 70
49e Box making - - 7,600 1() 13 3.7 0.62 1:2,
42a | Chocolate making 4,970 # S 1 - 70 0-40 || 1: 3,
and packings
42b 35 33 1,800 # 7 1 20 0.67 0.83
42c Cocoa packing - 4,690 6 to 8. 9 2. 70 0.56 || 1:20
42d Chocolate packing - 4,690 # 10 1 30 0 - 42 0 '82
42e 3 > 3 5 - || 4,690 7; 11 1 : 15 0-28 || 0 - 90
18e Burling - - 7,700 4 to 6 9 11 : 0 3-6 || 7-0
! |
•------ ~ * *- ,-- - -----
APPENDIX XVI.
DAYLIGHT ILLUMINATION.
By C. C. PATERSON (Joint Secretary) and J. W. T. WALSH.
It has been pointed out by many writers on the
subject of daylight that it is seldom realised how
great is the difference between the illuminations existing
simultaneously inside and outside ordinary buildings,
and, further, that the adaptability of the eye is so great
that it is quite incapable of estimating that difference.
The proportion of outside light reaching a point inside
a building is seldom as much as 1/10th, and more
often lies between 1/100th and 1/1000th; that is to say,
the illumination outside a building may be a thousand
or more times as great as that simultaneously existing
within. In spite of this very large difference, it will
be found that on a bright summer day, when the
outside illumination is of the order of 5,000 foot-
candles, work can be quite comfortably carried on at a
bench within a building where the illumination is only
1/1000th of this amount. Furthermore, the eye does
not perceive a very marked difference in passing from
the outside to the inside of the building, or vice versá.
The same is true of the variations which take place
from day to day, and even from hour to hour, in the
value of the outside illumination, for though this
variability is a matter of common observation, the
rapidity and magnitude of the variations in ques-
tion are only realised by the careful experimental
study of the illumination conditions existing through-
out the year at Some One Open position. So many and
so different are the causes of this variability that the
formulation of any rules for the predetermination of
the illumination under given conditions, even if pos-
sible, would appear to be of little practical value. This
uncertaintyrenders useless, as a criterion of the lighting
efficiency of a building, any isolated measurements of
the daylight illumination within it, for such illumi-
Imation will necessarily follow the continual fluctuations
of that existing outside.
The only reliable guide to such lighting efficiency,
therefore, will be the relation between these two
illuminations—that inside and that outside.
relation has, throughout this report, been termed the
daylight factor, and the meaning and use of the
term has been fully explained in Appendix XV.
This
It will be clear from the explanation there given that
two things must be known before the daylight illumi-
nation at any point in a building can be deduced. The
first of these is the daylight factor, and the second is
the Outside illumination at any given time of the year.
The former is readily obtained from any building by
simultaneous illumination measurements inside and
outside, and has been given for each point of obser-
vation in the factories visited in the tables containing
the results of these observations (Appendix
).
The second factor, viz., the outside illumination to be
expected, on the average, at any time of year, is the
principal subject of this appendix.
illumination with any certainty.
As explained above, it is impossible to predict this
All that can be done
is to give a general idea of the illuminations that have
been observed, on the average, to recur during the
different months of the year, and to indicate roughly
the limits between which it may be assumed that these
illuminations will be again reproduced in similar
circumstances.
G 2
64
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS :
The conditions exerting the greatest influence on
daylight illumination may be divided into three main
classes as follows:–
(1) Time of day.
(2) Time of year.
(3) Meteorological conditions.
These will be treated separately in the following
notes. -
1. Change of Daylight Illumination with Time of Day.
It may be assumed that, other factors being con-
stant, the rise of illumination on any day from sunrise
to noon, due to the earth's motion, will correspond
closely with the fall of illumination from noon to
sunset. From the measurements made it appears that
this fall is at a more uniform rate when there is a dull,
grey sky than when the sky is blue and cloudless. The
two curves in Fig. 1 show respectively the variations
of illumination observed on two such days.
FIG. 1.
Curves showing decline of illumination from moon to
sunset on two days in September.
Curve A.—Sunny and cloudless.
Curve B.-Dull grey sky.
1-0 2-0 5.0 . 4.0
Tifº E OF DAY
These days were actually September 25th and 30th,
1914. It has been confirmed, further, that the sunset
and sunrise illuminations do not vary with the time of
year, but only with the state of the sky and atmo-
sphere, and lie, generally, between 10 and 50 foot-
candles. An illumination of 25 foot-candles may be
taken as a fair average value. The results of some
illumination measurements at Sunrise and sunset are
given in Table 1.
• O 6-0 7. ()
TABLE I.
Illumination at Sunrise and Sunset.
Illumination
Date, 1914. (Foot- Character of Sky.
Candles).
Sunrise.
June 6 - 10 Completely covered with
clouds.
,, 8 - 25 Almost clear.
, 9 - 9 Overcast, except on horizon.
,, 10 - 13 Clear, light, fleecy clouds.
, 11 - 27 Blue; dense clouds on the
horizon. º
, 13 - 6-7 | Dull and cloudy.
,, 15 - 41 Clear blue.
Sunset.
June 6 - 7 Completely covered with
clouds.
,, 8 - 27 Clear sky, except on horizon.
, 9 - 4 4 || Rain and thunder.
, 11 - 6 Dull and raining.
,, 12 - 54 Blue ; a few clouds.
,, 27 - 54 Clear blue ; clouds on horizon.
July 2 - 42 Blue; some clouds
,, 4 - || 62 Clear and bright.
,, 16 - 15 Cloudy.
Aug. 31 - 28 Dull and overcast.
Sept. 7 - 32 Blue ; white clouds.
Oct. 10 - 9:3 Cloudy but bright.
Dec. 39 - || 34 Blue ; light clouds.
From a general consideration of the observations
obtained, the variation in the average daylight illumi-
nation during the day is of the nature of that shown in
Fig. 2 3.
:- o
FIG. 2.
Curves showing approximate variation of daylight
from 5 a.m. to 7 p.m. on average days in June,
September, and December.
E
3
6
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2
0
0
0
TEMBER
º
00
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5
()
()
()
5-0 6.0 7-0 8.0 9.0 10-0 || 6 10 2.0 3-0 4-0 5.0 6-0 7.0
TIME GOF DAY
On this diagram the horizontal scale represents the
time of day, and the vertical scale foot-candles of
illumination under an open sky. There are three
curves, representing average days in June, September,
and December respectively. A horizontai line has
been drawn through the curves at the 500 foot-candle
level for the purpose of illāstration, and it will be seen
that the line cuts the December curve at 10 a.m. and
2 p.m. It follows that any room in a factory for which
the daylight factor is below 0.2 per cent. will have less
than 1 foot-candle of daylight illumination before
10 a.m. and after 2 p.m. on an average day in
December, while in June the corresponding times are
6 a.m. and 6 p.m. respectively.
It may be said, further, that there is, on the average,
an outside illumination of about 100 foot-candles
30 minutes after Sunrise and before sunset, so that a
position in any factory with 1 per cent, daylight factor
has, on the average, an illumination of 1 foot-candle
30 minutes after sunrise and before sunset.
2. Change of Daylight Illumination with Time of Year.
As already stated, the sunrise and sunset illumi-
nations do not vary to any appreciable extent from
summer to winter. The midday illumination, how-
ever, falls from an average of about 4,000 foot-candles
in June to 700 foot-candles in December, the inter-
mediate distribution being of the nature of that given
in Fig. 3, the curve shown having been plotted from
actual observations.
FIG, 3.
Curve showing the average mid-day illumination for
each month of the year.
UGSEP 00TN0W.DEC
|}E( JAN FEB.MAR.APR MAY, JUN.
MONTH OF YEAR













APPENDICE8,
65
It must be remembered that these values are only
very approximate and vary greatly with the meteoro-
logical conditions. The values are only given in order
to afford some idea of the average illumination to be
expected at the time of year in question. In order to
obtain average values, a number of days were chosen
for the measurements in each month. These varied
between very bright and very dull, and the average in
each case may be regarded as a representative one.
3. Change of Daylight Illumination with Meteorological
- Conditions.
The variations in the daylight illumination arising
from even small changes in atmospheric or cloud
conditions are often surprisingly great and take place
with extreme rapidity. The diagrams in Fig. 4 show
the magnitude of such variations on representative
days.
FIG. 4.
Representative diagrams showing daylight fluctuations
over short periods.
Curve A.--A bright day in March, with white
- and grey clouds.
(Jurve B.-A dull, grey day in March.
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The first gives an approximate record of the day-
light illumination observed on a bright day in March
(17th), when there was a large number of grey and white
within a few minutes.
clouds over the sky. The second shows the compa"
rative steadiness found on a day with a very uniform
: dull grey sky at the same time of year (March
th). -
It will be seen from the first example that the
illumination may vary by upwards of 80 per cent.
Also two days of a different
type, though in the same month, may give widely
different average illumination values at the same time
of day. Thus the midday illumination on October
14th (when it was very dull and drizzling) was 150
foot candles, while three days later, at the same time
of day, it was 1,200 foot-candles. Of the various
factors affecting the illumination, the number and
brightness of the clouds are, perhaps, the most impor-
tant. A bright cloud upon which the sun is shining
has a brightness far exceeding that of the surrounding
blue sky, and as such a cloud changes its position in
the heavens, its brightness, as well as its capacity to
produce illumination at any particular position, will
both change considerably. With a large number of
such clouds in the sky it is not surprising that the
illumination should fluctuate rapidly. The clearness
of the atmosphere, too, has naturally a considerable
influence on the illumination, but this effect is not
capable of such rapid variations as that due to clouds.
The probable limits between which the daylight illumi-
nation at any time may be expected to lie are indicated
in Table II. The values there given are based on
9% months’ observations (taken at the National
Physical Laboratory from March to December 1914).
Observations over a more extended period might lead
to some modification of the averages given. The
values of illumination considered throughout are those
measured on a horizontal plane, placed in an open
field with a practically unobstructed horizon. The
direct sunlight was always shielded from the test-cards,

TABLE II.
Midday Illumination (Foot-Candles).
Month.
Highest. Lowest. Mean.
1914.
April - {-} gº 5,340 716) 3,200
May - tº sº 5,430 1,050 3,200
June - gº +- 5,160 2,420 4,100
July - tº &- Sufficient observations not
August gº gºe } available.
September - gº 3,030 870 1,800
October ſº gº 2,610 152 1,300
November - gº 2,500 I 30 1,100
T)ecember - $º 1,160 360 720

APPENDIX XVII.
THE MEASUREMENT OF ILLUMINATION.
Explanations of the terms “Illumination * and
“Surface Brightness” have been given in the Report
(page iv). It may be useful to consider here briefly
the methods by which they are measured.
The brightness of a surface, as has been shown,
depends not only on the amount of its illumination,
but also on the fraction of the imcident light which it
returns to the observer. This fraction is known as the
coefficient of reflection of the surface, and is often
conveniently expressed as a percentage. It varies from
about 90 per cent, in the case of very white materials
to 2 or 3 per cent. for black velvet. A perfectly white
surface would return 100 per cent. Of the light
incident on it, but no such ideal surface is known.
If the illumination at a certain surface is 10 foot-
candles, and the surface has a coefficient of reflection
of 50 per cent. (thus returning only half the light it
receives), it will only appear as bright tº a perfectly
white surface illuminated to half the extent, viz., to
5 foot-candles. It is often useful in this way to
express the surface brightness of an object in terms
of the illumination required at a perfectly white
surface to make the brightness of the latter equal to
that of the object in question.
G 3
66
DEPARTMENTAL COMMITTEE ON LIGHTING IN FACTORIES AND WORKSHOPS:
Example:–A piece of grey cloth has a coefficient
of reflection of 20 per cent. and is illuminated to
5 foot-candles. Its surface brightness would be
matched by a perfectly white surface illuminated to
5 x * Peº “” = 1 foot-candle. The equiva-
100 per cent. -
lent surface brightness of grey cloth under these
conditions is thus said to be 1 foot-candle.
It is here assumed, for the sake of simplicity, that
at a given illumination a surface has the same
brightness whatever be the direction from which it is
viewed, or whatever be the direction of the incident
light. It is obvious that in the case, for instance, 9f a
mirror this will not be true. If a beam of light
coming from a definite direction (e.g., that given by a
hole in a card placed in direct sunlight) fall upon a
mirror surface, there is one particular direction along
which the greater part of the light composing that
beam is reflected, and so regular is the reflection that
an observer sees an image of the hole as he looks
towards the mirror from that direction. From any
other direction, however, the mirror reflects practically
no light whatever towards the observer, all the light
having been sent off in the one direction. Such
reflection, concentrated almost entirely in one direc-
tion, is called “regular ” reflection. Supposing, now,
a very “matt’ (i.e., unglazed) surface, such as a sheet
of white blotting-paper, is put in the place of the
mirror and illuminated in the same way, no direction
can be found in which the reflected light is much
stronger than it is in any other direction. The
blotting-paper looks equally bright from all positions
because its surface has the property of scattering the
incident light and reflecting it in all directions. In
this case the reflection is said to be “diffuse.” Both
the mirror and the blotting-paper reflect approximately
the same amount of the total incident light (between
80 and 90 per cent.), that is to say, their coefficients of
reflection are the same, but in the case of the mirror the
reflection is regular, whilst in that of the blotting-paper
it is diffuse. The two cases considered are extreme, and
most surfaces fall between the two, that is to say, a
certain and usually the larger proportion of the light
incident on them is diffusely reflected, the remainder
being more or less concentrated in One direction. For
very many of the substances dealt with the proportion
of regularly reflected light is small enough to introduce
no serious practical error in ordinary measurements of
surface brightness, although in such measurements the
surface is always assumed to be completely diffusing.
This assumption has been made with regard to the
surfaces treated in this appendix.
APPARATUS FOR MEASURING ILLUMINATION,
An apparatus for measuring illumination consists,
in its simplest form, of two identical white surfaces so
arranged that they can be compared together. The
first (S1) is placed at the point where the illumination
is to be measured, and receives on it all the light
incident at that point; the second (S) is illuminated
to any desired and known amount by some source of
light under control. When the brightness of this
second surface matches the first One its illumination,
being known, is a measure of the unknown illumination
at surface 1. The various instruments used in practice
merely differ in the methods adopted for adjusting
the illumination at surface 2, and also in the devices
employed for conveniently comparing the two surfaces
together.
Arrangements are made within the instrument so
that when looking through an eye-piece one portion of
the field of view is occupied by a portion of surface S,
of variable brightness, whilst the other portion is
unobstructed Rsee diagram). Then, by suitably directing
the instrument, the surface S, may be seen filling the
unoccupied portion of the field of view. The brightness
of the variable surface S2 is then adjusted, in this case
by moving the lamp L towards or away from So, until
the whole field of view appears equally bright. The
illumination can then be at once read off on the scale,
S,
I ºl
P is the photometer case Containing L the electric
lamp, Sº the surface whose brightness can be varied by
moving L, and E an eye-piece. S, is the other surface
placed at the point at which it is desired to measure
the illumination produced by lamp F. The surfaces
S, and Ss are observed simultaneously through E, and
the handle H is moved until S, and s, appear equally
bright. As the movement of the handle regulates the
illumination at S, each position taken up by it corre-
sponds with some definite illumination. These illumi-
nations are marked on a scale over which moves a
pointer attached to the handle, so that when there
is equality of brightness the scale reading indicated
by the pointer gives at once the value of the illumina.
tion at S, which was desired.
If an operator desires to know the illumination at
the needle of a sewing machine, he has only to lay his
white surface S, on the table of the machine against
the needle, and direct his portable photometer towards
it, adjusting his instrument until, as described above
equality of brightness exists over the field of view.
The reading of the instrument then gives the illumina-
tion at the point on the sewing machine covered by the
white card. Usually it is the illumination at a hori.
Zontal plane which is required to be known, because, as
a rule, the object worked upon is approximately
horizontal, or has to be viewed by the workperson from
a point immediately above it. Cases, however, may
arise, such as on a compositor's frame, in which the
important plane is not horizontal but is appreciably
inclined, and in this case the card may have to be
placed at an angle. The illumination at a vertical
plane. IS seldom required, but if, for instance, the
illumination of picture galleries were under considera-
tion it is obvious that the vertical plane would be more
* than the horizontal one.
Will be seen from the foregoing description of a
photometer that although it is the jº. of the
two surfaces S1 and S, which are Compared, yet, since
they both have the same coefficient of reflection, the
instrument can be and is scaled to measure illumination.
It would be equally easy to scale the instrument to
indicate equivalent surface brightness, but measure-
ments of illumination are more often required than
those of surface brightness. If an ideally white

APPENDICEs. "
67
surface could be obtained for surface S, the scales of
illumination and equivalent surface brightness would
be identical. A measurement of illumination at the
white card, therefore, can be converted into a measure-
ment of its equivalent surface brightness by multiplying
the reading of the instrument by the coefficient of
reflection of the white card.
Iºxample :-If the illumination at the white card
is measured as 1 foot-candle, and the coefficient of
reflection of the white card is 0 85 (85 per cent.),
the equivalent surface brightness of the white card
at this illumination will be 1 × 0.85 = 0 85 foot-
candle. Similarly, if the standard surface in the
instrument be matched against the surface of any
other material, such as a piece of cloth or wood,
the equivalent surface brightness of such cloth
or wood can be determined by multiplying the
instrument reading by 0.85.
§The coefficient of reflection of any surface is, of
course, readily obtainable by measuring (1) the illumi-
nation at such surface, and (2) its equivalent surface
brightness under that illumination. The surface
brightness divided by the illumination gives, at once,
the coefficient of reflection.
The principle of the illumination photometer has
been explaimed above in its simplest form. By
adopting a suitable method of calibration it is not
necessary for the internal and external white surfaces
to be identical, nor for the external surface to be
detached from the instrument. These, however, are
details of construction and do not affect the main
principle.
The variable brightness of the surface S, within the
instrument is obtained in many ways in illumination
photometers now in common use.
Among these methods are the following:—
(1) Changing the distance of the internal surface
from the lamp illuminating it.
(2) Varying the intensity of the light from an
electric lamp shining directly on the
surface and contained within the instru-
ment. This is effected by introducing
into the lamp circuit a resistance operated
* by a slider with pointer attached.
(3) Changing the inclination of the surface to the
rays from a lamp. The change in inclina-
tion is produced by turning a knob to which
the pointer is attached.
(4) Using as light source to illuminate the
surface a greater or less area of another
constantly illuminated surface. The area
is changed by the movement of a shutter
controlled by a handle with pointer
attached.
The material used for the white surfaces must be
carefully chosen. No surface is obtainable which will
return all the incident light, but in practice a material
is chosen whose surface reflects as much of the light as
possible. This surface must, as far as possible, fulfil
the following conditions:—
(1) It must be readily reproducible, in order to
facilitate replacement without any necessity
for readjustment of the instrument which
has been calibrated by means of it. It will
be observed that any change in the co-
efficient of reflection of the standard surfaces
used with any given instrument would
invalidate the readings of the instrument to
the extent of the change.
(2) The surface must be as “matt” as possible, in
Order that it will appear equally bright
whatever be the direction from which it is
viewed.
(3) It must be white; that is to say, it must reflect
in equal proportions all the light rays
incident on it whatever may be their colour.
A material often used for the purpose is opaque
white celluloid prepared with a specially matt surface.
It is, as far as can be judged, quite white, and the surface
can be made so matt that over a considerable range
of direction the brightness remains sensibly the same.
If it becomes soiled the surface can, with a little care,
be restored to its original condition.

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