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COMPARATIVE ADVANTAGES
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OF THE
ATMOSPHERIC RAILWAY SYSTEM:
1
RAILWAY SYSTEM:
!
WITH
AN APPENDIX,
CONTAINING
Experiments on the Tyler Hill Inclined Plane of the Canterbury
and Whitstable Railway, showing the relative amount
of lost Power of the Rope Traction, as compared
with that of the Atmospheric System on the
Dalkey Inclined Plane.
BY PETER W BARLOW, M. INST. C. E.
WITH AN ABSTRACT OF THE DISCUSSION UPON THE PAPER.
EXCERPT MINUTES OF PROCEEDINGS
OF THE
INSTITUTION OF CIVIL ENGINEERS.
LONDON.
1845.
HISTORICAL & PHILOSOPHICAL
SOCIETY OF OHIO
UNIV
OF
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Library
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672
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LONDON:
Printed by WILLIAM CLOWES and Sons,
Stamford Street.
Trip apart
1-12-51 Fle
11-6-50
INSTITUTION OF CIVIL ENGINEERS.
February 25, 1845.
SIR JOHN RENNIE, President, in the Chair.
No. 714. "On the comparative advantages of the Atmospheric
Railway System." By Peter W. Barlow, M. Inst. C. E.
The author having been required to examine and to report upon the
question of the comparative advantages of the atmospheric railway
system, with a view to the propriety of its application to the Tun-
bridge Wells branch of the South Eastern Railway, and as there
appeared to him several results from the use of this mode of traction,
which had not apparently been previously noticed, he was induced to
lay his investigations on the subject before the Institution, in the
hope that they might be found to contain some useful information,
although the little time he was enabled to devote to it, prevented his
making any very detailed calculations.
In the application of stationary power to traction on a railway, by
means of the exhaustion of air in a pipe, several of the inconveniences
of the present mode of traction by a rope, are avoided, and the great
difficulty of rendering the pipe air-tight, has been in a great mea-
sure overcome by the ingenuity and mechanical skill of the inventors.
It is but fair to assume, in comparing the atmospheric system with
traction by locomotive power, that still further improvements will be
made in those features of the invention which relate to the mechanical
construction.
Whatever may be the result of the comparison, in a pure me-
chanical point of view, that is to say, in a comparison of the cheapest
and quickest mode of moving certain weights over a given distance,
it must be considered, whether the power required on railways gene-
rally, is of that uniform character which admits of mathematical com-
putation, and whether, by the adoption of the atmospheric or any
stationary power, certain rules and regulations are enforced, which
are inconsistent with the ordinary traffic on a railway.
I
4
ATMOSPHERIC RAILWAY SYSTEM.
On lines like the Greenwich or the Blackwall Railways, when the
traffic is perfectly uniform, consisting of a certain number of trains
daily, at stated intervals, the power admits of a mathematical com-
putation; but on railways generally, the power required is liable to
considerable irregularities; and a power, which is practically re-
stricted to carrying between certain given points only and at certain
intervals, would lead to great inconvenience.
On all railways not carried upon arches, a great deal of work is re-
quisite for the maintenance of the road and the works, which must
be entirely intermediate traffic, consisting of bringing ballast and
other materials to repair the road and works, the removal of slips,
&c., and one or more engines are constantly employed for these pur-
poses on all the principal railways. There is also traffic of coal and
lime at sidings, to various intermediate points on all railways; and at
the principal stations, much manual labour is saved by the locomo-
tive in moving goods, trucks, carriages, &c., from the siding to the
main line. The power for this purpose cannot be efficiently applied
by the atmospheric system, because it does not admit of traction
between intermediate points, except at a cost and inconvenience
which would be inconsistent with practice, and must prove an ob-
jection to the use of atmospheric or any stationary power. This can
be only surmounted by having locomotive engines for this purpose,
and it involves a small and consequently expensive locomotive esta-
blishment, renders necessary locomotive gradients, and consequently
prevents the saving which, it is contended, can be made in the con-
struction of the atmospheric railway, by the use of steeper gradients.
Another practical inconvenience, which will be found in the
atmospheric railway, is, that the journey cannot be repeated on a
length of pipe until after a given interval, which is necessary for
forming the vacuum; the power is therefore not always at instant
command, and the transmission of special trains and expresses is
materially interfered with.
The same objection will also, upon consideration, be found fre-
quently to interfere with the general traffic, at the stations where the
up and down trains pass, as it is evident both must wait, until the air
is exhausted from within the pipes to the next engines. The length
of this time will depend upon the extent of the pipe and the power of
the engine; but it could not be less than 6 minutes, which is a
serious loss of time to occur at the passing of every train, and on a
long line, with trains every half hour, would reduce the average speed
to 20 miles per hour If the length of pipe to each engine was
Ir
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11-6-400
ATMOSPHERIC RAILWAY SYSTEM.
5
extended to 10 miles, as has been proposed, this loss of time would
be more serious, and would amount to 20 minutes or half an hour,
unless very powerful engines were used.
Another important objection to the atmospheric railway, is that the
traffic is dependant upon keeping air-tight a great length of pipe, and
upon the perfect order of a great number of engines; in fact, it de-
pends upon the perfect order of an extensive, delicate, and compli-
cated machine, composed of an infinite number of parts, the failure
of any one of which, would render the whole machine useless; and it
must be evident, to any person practically acquainted with the main-
tenance of a railway, that the machinery of such an engine will be
liable to frequent interruptions, from causes which it would be im-
possible to control.
The subsidence and slips of embankments and cuttings, do not
now interfere with the traffic of a railway, unless they are of great
extent; because a line of rails, if injured, is soon replaced, in situa-
tions where the continuity of the pipe would be destroyed and the
traffic would be intercepted. Slips, which are not of sufficient mag-
nitude to excite public attention, and which, in fact, do not interfere
with the trains, are of more frequent occurrence, in wet weather, than
is supposed, and will render the maintenance of a pipe, in addition
to the rails, not only very difficult and expensive, but in many cases
impracticable.
There will also be another source of danger, from increased liability
of the carriages to run off the rails of the atmospheric railway. The
locomotive, from its great weight, runs over and destroys any im-
pediment which may be on the rails, but which would throw off a
carriage. Such impediments, it may be supposed, need not exist;
but in spite of every precaution, they are found, in practice, to do so
to a great extent. On many railways cattle are continually run over;
tools or planks are frequently left by the workmen on the rails
such things are also frequently put on designedly; stones and flints
also fall from the sides of the cuttings upon the rails. Such impedi-
ments are thrown on one side, crushed, or run over by the locomotive,
but a carriage would be thrown off by them; and by a very small
impediment, the traffic on the atmospheric line would be stopped and
serious injury would, in all probability, be done to the pipe and
machinery, which would require a considerable time to repair.
;
These objections to the system may be considered frivolous by
those unacquainted with the actual maintenance of a railway; but
R 2
6
ATMOSPHERIC RAILWAY SYSTEM.
the uncertain medium by which the traffic is maintained on the
atmospheric railway will be fatal to its use for any traffic of import-
ance. A person carelessly or maliciously disposed may, at any time,
totally destroy the connexion of the power; and it is well known
how frequently this has been attempted on existing railways, and
would be oftener successful but that the attempts fail, from the
great weight of the locomotive.
These remarks refer to long lines of railway, but the objections
above stated do not apply to short lines like the Greenwich and
Blackwall constructed on arches, and in such situations, unless fre-
quent intermediate stations are required, the system has undoubtedly
advantages from its superior quiet and speed, with light trains; and,
as will be seen by the following investigation, it will also in such
cases be comparatively more economical.
The question of the comparative cost of haulage, by the sta-
tionary and the locomotive systems, was thoroughly investigated,
when the locomotive engine was first introduced. It will be seen,
that in railways, where the trains are not numerous, the stationary
power, in whatever way applied, is worked under a great disad-
vantage, from the small portion of time which is actually occupied in
the passage of the trains on the length assigned to each stationary
engine.
The irregularity of traffic on a long line of railway, will be
illustrated by the occasional necessity of removing large bodies of
troops. The daily average traffic of several of the principal lines,
very
little exceeds the number of a full regiment of infantry; but it
may be necessary to convey several regiments on the same day, and
even at the same time; therefore to meet such a contingency, it is
evident, the power must be so great as to work at other times at
great disadvantage.
*
The actual lost power, in the locomotive engine, although
considerable, is not so much as might be expected, the greater
portion of loss being in the power required to convey its own weight
and that of the tender; consequently, the amount of lost power is
very much greater on lines with bad gradients, than on those with
favourable ones, and on steep gradients the atmospheric principle is
comparatively more advantageous, in a mechanical point of view.
It is necessary, however, to observe, that a very common error
exists in supposing that steep gradients are attended with compara-
ATMOSPHERIC RAILWAY SYSTEM.
7
tively little inconvenience on the atmospheric railway. They must,
of course, render necessary the additional power due to the increased
traction, which makes an important difference both in the first cost
and in the working expenses. Thus in the gradient on an incline of
1 in 50, the sectional area of the pipe and the power of the stationary
engines will be required to be four times that which is necessary on
a level railway, and the working expenses will be increased in the
same proportion; in fact, the cost of the apparatus, to give the re-
quisite tractive power on a single line of railway of the above incli-
nations, would exceed the total cost of a double line, constructed for
locomotive power. This result is very much at variance with the
statements made in the first instance by the inventors, as to the great
saving of cost in the first construction.
The result that steep inclines are better worked by the atmospheric
system, has been evidently arrived at without considering the cost of
construction, which becomes practically a very important question in
the atmospheric stationary power, from the large section of pipe that
is necessary. The outlay, as well as the working expenses, will be in-
creased nearly in proportion to the sectional area of the pipe, from the
circumstance, that the pressure is limited to that of the atmosphere, and
this limitation of the pressure is a great practical objection to the
atmospheric system; in fact, in comparing the atmospheric system
with traction by the rope, the latter will be found to have much the
advantage with steep gradients, and experience will show, that the
atmospheric system is practically much better adapted to level lines
of railway, than to those with steep gradients, which, if exceeding the
inclination adapted to locomotive power, will be worked more advan-
tageously by the rope. There are, however, few instances in which
the inclines are required to be so steep, that the locomotive cannot
be more advantageously applied; and the fact of the abandonment
of stationary power for the locomotive, on the inclines on the Man-
chester and Leeds railway, and on the Edinburgh and Glasgow
(the inclination of both being greater than 1 in 50) as well as in
other cases, is not only a proof of the improved capability of the
locomotive engine, but of the inconvenience found in practice from
stationary power.
The objection which will interfere most sensibly, with the adop-
tion of the atmospheric system, is the necessary outlay in the
engines and the pipe, and this seems to have been lost sight of in
the calculations of the economy of working, which have been made
by its advocates.
ATMOSPHERIC RAILWAY SYSTEM.
Referring to the calculations of the cost of working on the London
and Birmingham Railway; to lay down the apparatus of a double
line, with a pipe of the required area, would not be less than £10,000
per mile, or a total cost of £1,120,000; and the interest of this sum,
at 5 per cent., will be £56,000, or £500 per mile, or a sum very
nearly equal to the actual cost of working that railway by locomotive
power, and exceeding the average cost of most of the long lines. In
fact there is no doubt that respectable contractors could be found, who
would supply locomotive power, and work any railway, for the in-
terest of the sum which would be expended, in laying down the
atmospheric apparatus.
If the interest on the necessary additional outlay is equal to the
cost of working by locomotive, it is evident that it cannot be applied
to main lines already executed, even if the working expenses were
entirely saved.
It has been stated, that an economy may be effected in the cost of
the construction of the tunnels and the bridges, by avoiding the use
of the engine; but this is erroneous, as the dimensions are governed
by the size of the goods' trains, the carriages and the trucks, and not
by the engine.
A calculation has been made, showing a reduced cost of main-
tenance of the permanent road; but experience has shown, that in this
department any calculation must be so completely vague, as to be
totally without practical utility.
The chief cost of maintenance of way on ordinary lines, is from the
settlement of the embankments; and on new lines it is sometimes
extremely difficult to prevent an interruption of the traffic, during
the winter, from the sudden and irregular settlement which a few
hours may produce. On recently made embankments, it would
be found extremely difficult to keep in order the road with the
atmospheric pipe, and it could certainly only be done at a very
increased cost.
It may be argued, that as the weight of the engine running over
the road is avoided, less repair will be necessary. In cuttings, some
saving might be expected from this cause, if there was no pipe in
addition, but with this addition, and on a line with the ordinary pro-.
portion of embankment, it is to be apprehended, that the cost of
maintenance will become a serious expense.
ATMOSPHERIC RAILWAY SYSTEM,
9
From these observations, the following general results have been
arrived at:-
:-
1st. That the situations best adapted for the application of the at-
mospheric principle, are on lines where the trains are required to be
numerous. This must generally occur near towns, and in such cases,
additional advantages would be derived, from the absence of the noise
of either the locomotive or the rope, and such lines might also gene-
rally be constructed at less cost by the adoption of this mode of
working, so as to pay for the additional expenditure.
The circumstance of a railway being throughout on one inclined
plane, so that the carriages will run down with their own gravity, as
on the Dalkey line, is favourable to the atmospheric system.
The locomotive system would, however, also derive advantage from
the same cause, as the engine would return without using any
steam.
2ndly. That on any main line, with the average number of trains,
the interest on the cost of the atmospheric apparatus amounts to the
present actual annual cost of working by locomotive, and conse-
quently, it cannot be applied to any line or branch worked as part of
the same locomotive establishment, without an actual annual loss,
amounting to nearly the whole cost of working the atmospheric
engines.
It must also be evident, that it can never be applied to new lines,
under ordinary circumstances without actual loss, as no reduction in
the cost of the pipe can be made by the alteration of the gradients.
If the mode of rendering the pipe air-tight could be improved, so as
to work lengths of 10 or 15 miles each with one engine, it would
much reduce the loss of power; but these lengths would cause several
practical inconveniences if they could be obtained.
3rdly. That a great cause of lost power arises from all modes of
working a railway by stationary engines, inasmuch as the steam must
be kept up the whole 24 hours; while the locomotive power is prac-
tically required for a few hours only. This will amount, assuming
the average number of trains on railways, to three or four times the
consumption of fuel by the stationary principle. It may be said, that
when applied to long lines, a greater number of small trains would be
run, instead of a few large ones; and this would certainly be the best
plan. How far the increased traffic, arising from these facilities,
might pay the additional cost, it is impossible to say; but with any
10
ATMOSPHERIC RAILWAY SYSTEM.
:
number that can be run with advantage, the locomotive would be the
least expensive method, unless under peculiar circumstances. There is
also another objection arising from the amount of work which is re-
quired to be done at stations by locomotives, and, also the intermediate
work of various kinds, this, with the atmospheric system, must be done
by horse or manual labour at a much increased cost.
There is also the risk of certain stoppages of the traffic with the
atmospheric railway, not only from the stationary engines getting out
of order, but from the frequency (with every care that can be employed)
of obstacles on the road, which will throw a carriage off the rails;
injury to the pipe, by slips and subsidences, &c. These are of
frequent occurrence in embankments, and in a common road they can
be repaired in a few hours, but they would be sufficiently extensive to
entirely destroy the action of the pipe, and would stop the traffic for a
considerable period.
4thly. The most favourable feature in the atmospheric plan is the
avoiding the noise, both of the locomotive and the rope, and this will
lead to its adoption on short lines in the neighbourhood of towns, as it
will be the less objectionable to the residents in the neighbourhood;
and in these cases, as the trains are required to be numerous, and loco-
motive power on the small scale becomes comparatively costly, the
advantages of economy will also be in its favour; in other words, in
such cases, where stationary power has or may have been previously
used with economy, the atmospheric mode of traction would be ad-
vantageous; but whatever improvements may be made in its con-
struction, it must still possess the essential features of the stationary
principle, and must therefore, as has been previously shown, not
admit of application to a railway of general traffic.
The attainment of lengths of 10-miles each would evidently reduce
the great cause of loss of power in the present atmospheric railway, but it
would increase the inconvenience which must arise on long lines, from
the absolute necessity of intermediate power, and where two trains
meet, it is evident they must both wait, during the time the air is ex-
hausted out of 10 miles of pipe, which will not be less than 20
minutes or half an hour, unless stationary engines of very large
power be used.
The result, as to the effect of the resistance of the air at high
velocities, is very interesting. It has been shown by experiments,
that when a train attains a velocity of 35 miles per hour, the resist-
ance from this cause equals 50 per cent. of the tractive force, and
ATMOSPHERIC RAILWAY SYSTEM.
11
that it increases rapidly with higher velocities; this is fully proved
by the effect of windy weather on passenger trains; but it is re-
markably illustrated by a circumstance which occurred on the Canter-
bury and Whitstable Railway, since it has been under the author's
charge (and it appears to have been of frequent occurrence). A train
was entirely stopped in descending a gradient of 1 in 50, rendering
it necessary to use horse power, although the velocity of the wind at
the time could not have exceeded 60 or 70 miles per hour.
The result arrived at, that the average speed on a single line would
be reduced to 16 miles per hour in practice, from the pipes being full,
at the meeting of the trains, confirms the author's estimate of 20 miles
per hour; and it appears also to be shown so clearly as to admit of
no doubt, unless the advantage of frequent trains be abandoned.
is impossible, therefore, not to look with great interest on the experi-
ment of the South Devon line, where it is anticipated that more than
double that speed will be realized.
It
With reference to the lines on which the atmospheric system is in
course of execution, viz., the London and Croydon, and South Devon,
the results arrived at in the above investigation show, that the London
and Croydon (if not forining a portion of a trunk line), is a case in
which the power can be comparatively applied with advantage, and
the objections only apply to a limited extent, as the trains are fre-
quent, and the traffic consists chiefly of passengers, and as there
need be only one train met, the speed with a single line will pro-
bably be greater than with the locomotive engine, from the time
necessary with frequent stoppages, to get the locomotive engine up
to its speed.
The New Cross incline will be felt to be the greatest objection, as
the speed will be small (with the power proposed), with large trains,
from the increased tractive force which will be necessary.
The South Devon line is a case, to which it would appear from the
above results, that the atmospheric system is not adapted.
12
ATMOSPHERIC RAILWAY SYSTEM.
APPENDIX.
Experiments on the Tyler Hill Inclined Plane of the Canterbury and
Whitstable Railway, showing the relative amount of lost Power of the
Rope Traction, as compared with that of the Atmospheric System, on
the Dalkey Inclined Plane.
The Canterbury and Whitstable railway was constructed in the year 1830,
and was the first railway in the South of England. It was intended to be
worked by stationary power, and is composed chiefly of inclined planes of
various inclinations, from 1 in 36 to 1 in 50. The inclined plane at Tyler Hill,
where the experiments were tried, is 1 mile and 70 chains in length, with an
average inclination of 1 in 48.
The stationary engine is of 25 horses (commercial) power, with a cylinder 20§
inches diameter and 5 feet stroke, and was erected by Messrs. Stephenson of
Newcastle, in the year 1830. It will bring up 35 tons at an average rate of 71
miles per hour, on the incline of 1 in 48, and is, therefore, capable of producing
as great a useful mechanical effect as the Dalkey engine of 100 H. P., as it raises
more than half the load three times the altitude, on the same length of incline,
in nearly the same interval of time.
With a result so important and unexpected, it was necessary, in order to render
the deductions perfectly satisfactory, to adopt every practical means of ascer-
taining the exact power exerted during the experiment; an indicator and
counter were attached to the engine, and the diagrams, &c., from which the
result was obtained, are given in Plates 3 to 10, in order that the accuracy of the
calculations may be tested.
From an examination of the diagrams it will be perceived that the slide valves
of the engine were very inaccurately set during the first seven experiments;-
the eighth was made the next day, after the slides had been adjusted; this ex-
periment, therefore, shows a better result. Further alterations of the slides,
had it been possible to have made them, within the time allotted for the ex-
periments, would have ensured still more satisfactory results.
Much misapprehension has prevailed from comparing the atmospheric with
the locomotive system, in consequence of using the same arguments as were
brought forward in favour of the stationary power, and it will be apparent, from
reading the Report of the Atmospheric Committee, that they have been
misled by these arguments, and that they would have arrived at the same con-
clusions if they had been considering the system of stationary engine and
rope traction, and for precisely the same reasons. A comparison of the at-
mospheric system with that of rope traction is therefore important, in order to
ascertain the practicability, or the applicability of the atmospheric system.
These experiments may, it is contended, be received as strong arguments
against the commercial practicability of the atmospheric system.*
The experiments were entrusted to Mr. Gastineau, who followed with great accuracy the
author's instructions.
ATMOSPHERIC RAILWAY SYSTEM.
13
The exact inclination of each portion of the plane was accurately ascertained,
posts were placed at intervals of 5 chains, and the time of passing each post was
carefully registered. The tables of experiments give the weights of the car-
riages and load of each train, the number of revolutions of the engine, the speed
of the piston per minute, the average pressure upon the piston, the pressure
in the boiler, and the estimated power of the engine.
The indicator diagrams in Plate 11 exhibit the power expended in moving
the rope alone, for which purpose that experiment was tried.
From these comparative tables the following results are obtained.
1st. That an engine of 25 commercial H. P. on the Whitstable line, working
at an average of 50 H.P. of 33,000 lbs., gives an useful mechanical result, nearly
equal to the Dalkey engine of 100 commercial H. P., working at 160 H. P.; or
in other words, it raises trains of 30 tons on an incline of 1 in 48, at the same
speed that the Dalkey engine raises trains of 66 tons on an incline of 1 in 138,
which is evidently nearly an equal mechanical effect.
2ndly. That the lost power on the Whitstable Incline averages ths of the
whole power, while on the Dalkey line it averages ths of the whole power.
3rdly. That the loss in transmitting the power to the train, as shown in Mr.
Samuda's experiments, exceeds ths of the whole power, while in his state-
ment sent to the Committee it was estimated at 4th, which explains the differ-
ence in the calculations of the power required on the atmospheric lines.
TO
4thly. The amount of lost power appears, in Mr. Stephenson's experiments,
to be nearly uniform, throughout all the degrees of vacuum; this at first sight
appears extraordinary, but it is evidently caused by the circumstance of the
useful mechanical effect being computed by multiplying the resistance due to
friction and gravity into the mean velocity in feet, without regarding the resist-
ance of the air, which was greater with the low degrees of vacuum, because the
velocities were greater.
It is, however, difficult to estimate this, as the velocities were variable; but
assuming 20 lbs. as adopted by Mr. Stephenson, for 30 miles per hour, it will
affect the result, to the amount of about 25 per cent., which may be taken as an
approximation to the truth; but whatever it may be, it is evident, from the
uniformity of the results, that the effect of the increased leakage, at the higher
degrees of vacuum, does not exceed the increased resistance of the air, and
thereby proves that the leakage is not the main source of lost power.
The experiments by Mr. Samuda and M. Mallet show a less mechanical effect
than those by Mr. Stephenson; which arises evidently from their holding the
train by the breaks until the vacuum was made, in order to obtain as great a
maximum speed as possible.
With a result showing so large an amount of lost power, it becomes interest-
ing to inquire to what it is to be attributed, and how the total amount is made
up; but this would require experiments more especially devoted to that ques-
tion. It is, however, evident that a large portion is of a description which
(although not lost in a theoretical point of view) is not under mechanical con-
trol, either with heavy or light loads.
With heavy loads and a high vacuum, the power of the engine required to
form the vacuum, will amount to the greater proportion of the whole power
exerted, and which will be practically lost; with the other extreme, of light loads
and a small vacuum, the friction of the air in the pipe becomes an equally large
proportion of the power expended, because the whole bulk of air must be ex-
hausted, however small the load may be. In fact, the atmospheric medium of
14
ATMOSPHERIC RAILWAY SYSTEM.
traction may be practically represented by a rope without weight, but so ex-
tremely elastic, that with a high vacuum, the larger proportion of the power of
the engine, is required to give it sufficient tension, to sustain the required load.
With small loads, the friction of the air on the sides of the tube, will also form
a large proportion of the power exerted by the engine, so that there will be
one particular vacuum and load, with any given engine and pipe, in which
the sum of these losses will become the least possible; but whatever this may
be, it is evident the amount must be fatal to the atmospheric system as a mode
of applying stationary power.
There is also a loss of power necessarily arising from the construction of the
air-pump, and, in addition to that from leakage, there will be a certain loss from
the atmosphere not having time to act with full effect on the piston.
It must be apparent, that the loss from leakage does not form a large propor-
tion of the lost power, and there is therefore but little field for mechanical
improvement, which has been urged as an argument in favour of the system.
This loss of time and of power, from the interval necessary to get up the
required vacuum, will have the effect of reducing the average rate of travelling
on a single line of atmospheric pipe, considerably below that of a locomotive line;
because such loss of time must occur at the meeting of every train, and with
trains running at intervals of half an hour, this delay must necessarily occur
every quarter of an hour.
Let A, B, C, D, in the annexed diagram, represent the position of the
engines on an atmospheric line, the first section, A to B, being similar to the
Dalkey line.
A
B.
"
0
1
ભ
2
C
3
4
D
5
6 miles.
The best result obtained from the experiments on the Dalkey line was the
transport of a train of 30 tons in five minutes. Now, assuming three trains
per hour to be required, if there was only one engine, the train, when it
arrived at B, would have to wait five minutes, which would make the total
time of traversing 13 miles ten minutes, being an average speed of 10 miles
per hour, although the extreme speed may have reached 35 miles per hour.
If the engines at B, C, D were double engines, the average speed would be
doubled with double the number of trains.
From this it appears, that on a railway formed of sections similar to the
Dalkey line, with single engines, or 100 H. P. (of 33·000 lbs.) per mile, a train
of 30 tons would make three trips each way per hour, at an average speed of
10 miles; and if the engines were double (i.e., 200 H. P. per mile), six trips
each way per hour might be effected, at an average speed of 21 miles per hour,
which is the simplest case of a long line.
In the proposed atmospheric lines, the power is intended to be arranged as
shown in the annexed diagram.
A
B
C
D
E
Single. Eng.
Dble
Eng.
Single. Eng.
Dble
·
Eng.
F
Single. Eng.
G
Dble
Eng.
•
}
I
1
1
1
1
1
2
3
4
5
6
my
8
9
10
11 12
13
14
15 miles
The length of the section A to B is 23 miles, double engines being placed at
alternate sections. Now assuming the most favourable case, of no increase of
leakage, or friction, from the increased length, it will be found that with
ATMOSPHERIC RAILWAY SYSTEM.
15
engines at B and C, of similar power to that at Dalkey, it would be requisite,
in order to transport a train of 30 tons from A to C,
To obtain a vacuum at A = to 13 lbs. per square
inch.
3.57 minutes.
To pass from A to C, at a speed of 30 miles per 10.
hour.
Allow for irregularity of meeting
1.43
Total
15 minutes.
Therefore, in a line with meeting points every five miles, with similar gradients
and power to the Dalkey line, i. e., 105 H. P. per mile (without spare engines),
the greatest effect will be, to transport trains of 30 tons every half-hour, at an
average speed of 30 miles; which is evidently an insufficient power to insure
punctuality with the ordinary traffic of a railway.
16
ATMOSPHERIC RAILWAY SYSTEM.
OBSERVATIONS ON TRAIN.
Rise.
Distance.
Posts.
Gradients.
Feet.
Miles. Chains.
No.
EXPERIMENT No. 1.—


Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per Hour
from commence-
ment.
Velocity per Hour
over each 5 Chains.
Weight of Train.
Seconds. Seconds. Miles. Miles. Tons.
0
5
•
· 125
10
1 in 42.87
15
for 20 chains.
• 25
30
012♡ +
0
23.45
41
41
5.5
74
33
6.09
6.8
3
105
31
7.3
4
140
35
6.4
6.5
30.79
1 in 40.84
for 12 chains.
• 375
223
25
5
175
30
6.
208
3888888335
6.5
6.5
6.8
50.18
35
1 in 45.76
•5
40
for 14 chains.
45
789)
242
34
6.6
274
32
6.5 7.03
307
33
6.8
70.37
.625
50
10
339
32
6.6
7.03
1 in 58.10
55
11
370 31
7.3
for 12 chains.
⚫75
60
12
400
30
6.7
7.5
84.00
1 in 48.76.
65
13
427
27
8.3
.875
70 14
455
28
6.9
8.04
75
15
484
29
7.8
1 in 56.00
1.0
80
16
512
28
7:08.04
for 28 chains.
85
17
545
33
6.8
116.95
1.125
90
18
569 24
7.1
9.3
95
19
600
31
7.3
1 in 51.65
[1.25
100
20
630 30
7.1 7.5
for 18 chains.
105
21
660 30
7.5
!
140.05
1.375
110 22
1 in 47.3
for 20 chains.
1.5
115 23
120 24
222
690 30
7.1 7.5
125 25
719 29
752 33
782 30
7.8
7.2
6.8
7.5
167.96
1.625
130 26
813 31
7.2
7.3
1 in 48.95
for 16 chains.
1.75
135 27
140 28
840 27
869 29
8.3
7.2 7.8
Weight of Carriages and Waggons
CC
Passengers and Goods
9.475
13.975
189.53
ATMOSPHERIC RAILWAY SYSTEM.
17
555 310
May 15th, 1845.

Time of Observations.
Seconds.
OBSERVATIONS ON ENGINE.
Revolutions of Engine.
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
No.
0
0
0
No.
Feet.
0
0
Diagrams.
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
per Square Inch in
Boiler.
Pressure of Steam
Power.
No. Sq. In.
lbs.
lbs. Horses.
334.2
0
30
126
61
33.6 336
1
16.5 25 56.1
196
100
36.0
360
2
13.4
48.8
622 350
719 405
33.0 330 3
14.0
46.
801 450
J
REMARKS.'
The train consisted of
five carriages, two
of them overloaded.
Light wind, contrary.
18
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76
EXPERIMENT No. 2.—
OBSERVATIONS ON TRAIN.

Rise.
Distance.
Posts.
Gradients.
Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per Hour
from
ment.
commence-
Velocity per Hour
over each 5 Chains.
Feet.
Miles. Chains. No.
Seconds. Seconds.) Miles.
Miles.
Tons.
0
0
0
35.0
5
1
44
44
5.1
• 125
10
2
83 39
5:4
5.7
1 in 42.87
15
3
120
37
6.08
for 20 chains.
⚫25
20
4
160
40
5.6
5.6
30.79
1 in 40.84
25
5
200
40
5.6
for 12 chains.
.375
30
6.
243
43
5.5
5.2
50.18
96
35
7
284 41
5.5
12.05
22.95
2224
1 in 45.76
•5
40
8
323 39
5:6
5.7
for 14 chains.
45
9
363
40
5.6
70.37
.625
50
10
401
38
5.6
5.9
1 in 58.10
55
11
434 33
6.8
·
for 12 chains.
•75
60
12
469 35
5·7
6.4
84.00
65
13
503
34
6.6
•
.875
70
14
539
36
5.9
6.2
75
15
572
33
6.8
·
1 in 56.00
for 28 chains.
1.00
80
16
609
37
5.9
6.08
85
17
645 36
6.2
:
116.95
1.125 90
18
682
1 in 51.65
95
19
721
for 18 chains.
1.25
100
20
761
105
21
803
A A CO C
37
5.9
6.08
39
5.7
40
5.9
5.6
42
5.3
:
140.05
1.375 110
115 23
1 in 47.3
for 20 chains.
1.5
120
125
25
2222
849 46
891
24
941 50
988 47
FORA
5.8 4.9
42
5.5
5.7
4.4
:
4.8
167.96
1.625
1 in 48.95
for 16 chains.
1.75
130 26 1033 45
135 27 1068
140 28 1124
5.6 5.0
35
56
5.6
6.4
4.03
189.53
Weight of Carriage and Waggons
,,
Passengers and Goods
Weight of Train.
ATMOSPHERIC RAILWAY SYSTEM.
19
211
146
86
May 15th, 1845.

OBSERVATIONS ON ENGINE.
Time of Observations.
Revolutions of Engine
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
Seconds.
No.
No.
Feet.
0
89
0
0
No.
Diagram.
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam per
Sq. In.
lbs.
334.2
34
Square
Incli
in
Boiler.
Ibs.
Horses.
27.7
277
1
19.6
30
54.9
27
574
273
29.1 291
2
16.5 25
48.6
646 308
857 398
920 428
28.5 285
3
16.0 24 46.1
1038 463
22.7 227
4
15.6 25 35.8
1091
483
C
The train consisted of
eight carriages, two
of them overloaded.
Light wind, contrary.
REMARKS.
20
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76.
OBSERVATIONS ON TRAIN.
Rise.
Distance.
Posts.
Gradients.
EXPERIMENT No. 3.-

Time of passing Posts.
Time of going over
each 5 Chaius.
Velocity per Hour
from commence-
ment.
Velocity per Hour
over each 5 Chains.
Feet.
Miles. Chains. No.
Seconds. Seconds. Miles.
Miles. Tons.
0
5
• 125
10
1 in 42.87
15
for 20 chains.
• 25
20
01234
wwww:
0
19.575
38
38
5.9
68
30
6.7
7.5
99
31
7.3
129
30
6.9 7.5
30.79
1 in 40.84
for 12 chains.
•375
225
25
5
161
32
7.03
30
6
193
32
6.9 7.03
50.18
1 in 45.76
.5
AC
35
40
for 14 chains.
45
689
7
224
31
7.3
255
31
8.8
7.3
284
29
7.8
:
70.37
.625
1 in 58.10
for 12 chains.
.75
800
50 10
317
33
7.1
6.8
55 11
345 28
60
12
375
30
8.04
7.2 7.5
84.00
Passengers and Merchandise
65
.875
59
13
402
70 14
433
75 15
463
1 in 56.00
for 28 chains.
1.0
80 16
85 17
492
524
22828
27
8.3
7.2 7.3
30
7.5
29
7.4
7.8
32
7.03
116.95
1.125
359
90 18
554 30
7.3
7.5
95
19
1 in 51.65
1.25
100 20
585 31
616 31
7.3
7.3
7.3
for 18 chains.
105
21
647
31
7.3
:
140.05
1.375
110
22
679
115
23
711
1 in 47.3
1.5
120
24
744
for 20 chains.
125
25
777
22333
7.3
7.03
7.03
7.2
6.8
6.8
167.96
1.625
130
26
809
32
7.2
7.03
1 in 48.95
135
27
842 33
6.8
for 16 chains.
1.75
140
28
874 32
7.2 7.03
Weight of Carriages and Waggons.
6c
8.8
10.775
Weight of Train.
189.53
ATMOSPHERIC RAILWAY SYSTEM.
21
$
May 15th, 1845.

OBSERVATIONS ON ENGINE.
Time of Observations.
Seconds.
0
Revolutions of Engine
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
No.
0
Diagrams.
No.
Feet.
No.
:
:
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam
per Square Inch in
Boiler.
Power.
Sq. In. lbs.
lbs. Horses.
334.2
0
175 100
29
34.7
347
1
13.5
244
140
390
:
:
:
513 300
33.6
336
2
638
370
720
771 440
:
:
10.5
21
25
23
REMARKS.
47.4
The train consisted of
six carriages, two of
them overloaded.
Light wind, contrary.
35.7
31.2 312
3
9.7
30.6
829 470
19
© 2
22
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76.
Rise.
Distance.
Posts.
Gradients.
OBSERVATIONS ON TRAIN.
EXPERIMENT No. 4.-

Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per Hour
from
ment.
commence-
Velocity per
Hour
over each 5 Chains.
Feet.
Miles. Chains. No.
Seconds. Seconds. Miles. Miles.
Tons.
· 125
10
1 in 42.87
15
for 20 chains.
•25
20
30.79
1 in 40.84
25
for 12 chains.
⚫375
30
01234
0
95
56
25
0
31.14
:
45
45
5.0
83 38
5.4
5.9
120 37
6.08
158 38
5.7
5.9
197 39
5.7
6
236 39 5.7
5.7
50.18
35
1 in 45.76
•5
40
for 14 chains.
45
780
274
333
38
5.9
313 39 5.7
5.7
9
349 36
6.25
70.37
• 625
1 in 58.10
for 12 chains.
•75
650
50 10
55 11
420 33
888
387 38 5.8
5.9
6.8
60
12
454 34
5.9
6.6
84.00
65
13
486 32
7.03
.875
70
14
522 36
6.03 6.25
75 15
553 31
7.3
1 in 56.00
for 28 chains.
1.0
80
16
583 30
6.1
7.5
85
17
623 40
5.6
116.95
1.125
90
18
657
34
6.1
6.6
95 19
693
36
6.25
1 in 51.65
for 18 chains.
1.25
100
20
728
35
6.1 6.4
105
21
765
37
6.08
140.05
1.375
110
115
1 in 47.3
1.5
for 20 chains.
120 24
125 25
2223
804
840
88888
39
6.1
36
5.7
6.25
880 40 6.1 5.6
918 38
5.9
167.96
1.625
130
26
956 38 6.1
5.9
1 in 48.
135
27
993
37
6.08
for 16 chains.
1.75
140
28
1032
39
6.1
5.7
Passengers and Merchandise
Weight of Carriages and Waggons
11.34
19.8
Weight of Train.
189.53
ATMOSPHERIC RAILWAY SYSTEM.
23
May 15th, 1845.

OBSERVATIONS ON ENGINE.
Time of Observations.
Revolutions of Engine
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
Seconds.
No.
0
65
140
0
Diagram.
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam per
Square Inch
Boiler.
по
No.
Feet.
No.
Sq. In.
::
:
Power.
lbs.
lbs. Horses.
334.2
36
32
:
30
181
84
28.4 284
1
14.8 28 42.6
276 129
484
234
31.1311.0 2
11.2
24 35.9
619
304
851
414
954 459
26.3
263
3
:
10.9
23
21 29.3
REMARKS.
The train consisted of
eight carriages, two
of them overloaded.
Light wind, contrary.
24
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76'
EXPERIMENT No. 5.-
OBSERVATIONS ON TRAIN.

Rise.
Distance.
Posts.
Gradients.
Feet.
Miles. Chains.
No.
Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per Hour
from commence-
ment.
over each 5 Chains.
Velocity per Hour
Weight of Train.
Seconds. Seconds. Miles. Miles. Tons.
0
0
5
• 125
10
1 in 42.87
15
for 20 chains.
•25
20
0123 +
12.125
32
32
7.03
60
28
7.5
8.04
87
27
8.3
4
112
25
8.06
9.01
30.79
1 in 40.84
for 12 chains.
⚫375
20
25
5
138
30
6
164 26
228
26
8.6
8.2
8.6
50.18
35
1 in 45.76
•5
40
78
190
26
8.6
214 24
8.4
9.3
for 14 chains.
45
9
240 26
8.6
70.37
•625 50
10
265
1 in 58.10
55
11
290
for 12 chains.
•75
60
12
310
2925
8.5
9.01
9.01
20
8.7
11.2
84.00
65
13
339 29
.875
70
14
361 22
8.5
7.8
10.2
75
15
384 23
9.7
1 in 56.00
for 28 chains.
1.0
80
16
407
23 8.8
9.7
85
17
433
23
9.7
116.95
1.125
90
18
453
20
8.9
11.2
95
19
479
26
8.6
1 in 51.65
for 18 chains.
1.25
100
20
502
23
8.9
9.7
105
21
526 24
9.3
140.05
1.375 110
22
549 23
9.06
9.7
115
23
572 23
9.7
1 in 47.3
for 20 chains.
1.5
120
24
596 24
9.09
9.3
125
25
619
23
9.7
:
167.96
1.625 130
1 in 48.95
135
for 16 chains.
1.75 140
2288
26
27
641 22
663 22
9.1
10.2
10.2
686 23
9.2 9.7
Weight of Carriages and Waggons
>>
Passengers and Merchandise
6.825
5.3
189.53
ATMOSPHERIC RAILWAY SYSTEM.
25
296
160
426
300
542
385
May 15th, 1845.
OBSERVATIONS ON ENGINE.

Time of Observations.
Revolutions of Engine
Revolutions of Engine]
per Minute.
Speed of Piston per
Minute.
Seconds.
No.
No.
0
0
125 80
:
:
Feet,
No.
Diagrams.
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam
per Square Inch in
Boiler.
Sq. In.
lbs.
lbs.
334.2
28.0
280
1
10.4
28 29.4
44.0
440
2
8.0 25 35.6
Power.
Horses.
REMARKS.


The train consisted of
five carriages.
Light wind, contrary.
26
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76.
OBSERVATIONS ON TRAIN.
Rise.
Distance.
Posts.
Gradients.
EXPERIMENT No. 6.-

Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per
Hour
from commence-
ment.
Velocity per Hour
over each 5 Chains.
Feet.
Miles. Chains.
No.
Seconds. Seconds. Miles.
Miles.
Tons.
0
0
0
0
27.8
5
1
35
35
6.4
• 125
10
1 in 42.87
15
for 20 chains.
• 25
20
234
76 41
5.9
5.5
120
44
5.1
161
41
5.6
5.6
30.79
1 in 40.84
for 12 chains.
⚫375
25
25
5
202
41
5.5
30
6
245
43
5.5 5.2
50.18
35
1 in 45.76
.5
40
for 14 chains.
45
789
289
44
5.1
330
41
5.4 5.5
370
40
5.6
70.37
• 625
50
10
410
1 in 58.10
55
11
445
for 12 chains.
.75
60
12
480
Coco
40
5.4
5.6
35
6.4
35
5.6
6.4
84.00
65
13
515
35
6.4
•
•875
70
14
549 34
5.7
6.6
75
15
581 32
7.03
•
1 in 56.00
for 28 chains.
1.00
80
16
618
37
5.8
6.08
85
17
649 31
7.3
116.95
1.125
90
18
686 37
95
19
722 36
1 in 51.65
1.25
100 20
760
for 18 chains.
105 21
798
38888888888
5.8
6.08
6.2
•
5.9
5.9
5.9
140.05
1.375
1 in 47.3
1.5
for 20 chains.
110 22
115 23
120 24
125 25
838
874 36
915
954
0=8938
40
5.1
5.6
6.2
41
5.9 5.5
5.7
167.96
1.625
1 in 48.95
for 16 chains.
1.75
130 26
135 27
140 28
991 37
1030
1068
39
38
5.8 6.08
5.07
5.9 5.9
•
10.0
•
17.8
Weight of Carriages and Waggons
55
•
Passengers and Merchandise
Weight of Train.
189.53
ATMOSPHERIC RAILWAY SYSTEM.
27
May 15th, 1845.

OBSERVATIONS ON ENGINE.
Time of Observations.
Revolutions of Engine.
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
Seconds.
No.
No.
Diagram.
Inch
in
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam per
Feet.
No.
Sq. In.
0
0
:
91
37
26.9
269
1
169
72
692 322
27.5 275
2
779 362
893 412
:
334.2
13.0 24 36.2
26.4 264
3
12.9 23 34.5
963 442
lbs.
Square
Boiler.
Power.
lbs. Horses.
30
16.1
42.9
29
REMARKS.
The train consisted of
seven carriages, two
of them overloaded.
Brisk wind, contrary.
28
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76
EXPERIMENT No. 7.-
OBSERVATIONS ON TRAIN.
Rise.
Distance.
Posts.
Gradients.
Feet.
Miles. Chains.
Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per Hour
from
ment.
commence-
Velocity per Hour
over each 5 Chains.
No. Seconds. Seconds. Miles. Miles. Tons.
0
5
•125
10
1 in 42.87
15
for 20 chains.
•25
20
01234
0
14.812
34 34
65 31
6.6
6.9
7.3
96 31
7.3
128
32
7.04 7.03
30.79
1 in 40.84
for 12 chains.
•375
235
25
5
159
31
-.3
30
6
190 31
7.1
7.3
50.18
7.5625
7.25
1 in 45.76
•5
for 14 chains.
AAC
35
40
45
789
221
31
7.3
252 31
7:1
7.3
281
29
7.8
70.37
.625
50
10
311 30
7.2
7.5
1 in 58.10
55
11
341 30
7.5
for 12 chains.
.75
60
12.
368
27
7.3
8.3
84.00
65
13
398 30
7.5
•875
70
14
427 29
7.3
7.8
75
15
454 27
8.3
1 in 56.00
for 28 chains.
1.0
80
16
483
85
17
510
22
29 7:4
7.8
27
8.3
116.95
1.125 90 18
95 19
1 in 51.65
for 18 chains.
1.25 100
105 21
2222
538 28
7.5
8.04
568
30
7.5
20
596 28
7.6
8.04
624
28.
8.04
140.05
1.375
110 22
ON
652
28
7.6
8.04
115 23
681 29
7.8
1 in 47.3
for 20 chains.
1.5
120 24
710 29
7.6
7.8
125 25
738 28
8.04
167.96
1 in 48.95
for 16 chains.
1.75
1.625 130 26
135 27
140 28
765 27
792
819 27
222
7.6
8.3
27
8.3
7:7
8.3
Weight of Carriages and Waggons.
""
Passengers and Merchandise
Weight of Train.
:

189.53
ATMOSPHERIC RAILWAY SYSTEM.
29
May 15th, 1845.
OBSERVATIONS ON ENGINE.

Time of Observations.
Revolutions of Engine.
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
Seconds.
No.
No.
0
0
233 135
429 255
567 340
616
370 37.0
Diagrams.
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Presssure of Steam
per Square Iuch in
Boiler.
Feet. No. Sq. In. lbs.
:
36.8 368
1
370
2
750
450
37.0 370
799 480
3
:
:
9.8
334.2
:
10.3 29
9.5 24.5
35.6
:
32.2
Power.
lbs. Horses.
35
38.3
REMARKS.
The train consisted of
five carriages.
30
ATMOSPHERIC RAILWAY SYSTEM.
1 in 48.76.
EXPERIMENT No 8.-
OBSERVATIONS ON TRAIN.

Rise.
Distance.
Posts.
Gradients.
Feet.
Miles. Chains.
Time of passing Posts.
Time of going over
each 5 Chains.
Velocity per
Hour.
Velocity per Hour
over each 5 Chains.
Weight of Train.

No. Seconds. Seconds. Miles. Miles. Tons.
0
5
• 125
10
1 in 42.87
15
for 20 chains.
• 25
20
0123¬
0
[35.225
34 34
6.6
63 29 7.1
7.8
93
30
7.5
4
122
29 7.3
7.8
30.79
1 in 40.84
for 12 chains.
⚫375
25
25
30
56
153
31
7.3
183
30 7.5
7.5
50.18
35
1 in 45.76
⚫5
40
for 14 chains.
45
689
7
213 30
7.5
243 30
7.3
7.5
273
30
7.5
70.37
.625
50
10
302
29
7.4
7.8
1 in 58.10
55
11
328 26
8.7
for 12 chains.
.75
60
12
354 26
7.6
8.7
84.00
.875
1521
65 13
380
26
8.7
70 14
407
27
7.8
8.3
75 15
433
26
8.7
1 in 56.00
for 28 chains.
1.00
80 16
462
29
7.7
7.8
85
17
488
26
8.7
116.95
1.125
90
18
517
29
7.8
7.8
95
19
546 29
7.8
1 in 51.65
1.25
100 20
577 31
7.8
7.3
for 18 chains.
105
21
608 31
7.3
140.05
1.375
110
115
1 in 47.3
1.5
for 20 chains.
120 24
125 25
2323
641 33 7.7
6.8
673
32
7.03
709
36
7.7
6.2
745 36
6.2
167.96
1.625
130
26
779
34
7.5 6.6
1 in 48.95
135
27
813
34
6.6
for 16 chains.
1.75
140
28
847
34
7.4
6.6
Weight of Carriages and Waggons
14.025
Passengers and Merchandise
21.2
189.53
ATMOSPHERIC RAILWAY SYSTEM.
31
May 15th, 1845.

OBSERVATIONS ON ENGINE.


Time of Observations.
Revolutions of Engine
Revolutions of Engine
per Minute.
Speed of Piston per
Minute.
Diagram.
Seconds. No.
No.
Feet.
No.
0
0
134
80
216
130
36.7 367
1
Area of Piston.
Average Pressure of
Steam per Square
Inch on Piston.
Pressure of Steam per
Square Inch in
Boiler.
Sq. Iu. lbs.
334.2
:
18.9
357
2201
40.0 400
2
14.8
432 270
:
:
Power.
lbs. Horses.
70.4
8.09
561 350
33.0 330 3
14.6
48.7
625 385
746
455
29.7 297
4
14.1
807
485
:
42.4
REMARKS.
The train consisted of
ten carriages.
Brisk side wind.
ATMOSPHERIC RAILWAY SYSTEM.
32
TABLE, showing a COMPARISON of the USEFUL MECHANICAL EFFECT of the DALKEY ENGINE, as applied by the ATMOSPHERIC PIPE, with
that of the TYLER HILL ENGINE on the CANTERBURY and WHITSTABLE RAILWAY, as applied by the ROPE.
DALKEY ENGINE; 100 Commercial H.P.; Cylinder 34 in.
TYLER HILL ENGINE; 25 Commercial H.P.; Cylinder 20ğths in.;
5 feet Stroke.
In.
1234+
Tons.
Miles. Feet. lbs. H.P.
18.5 26.5 151 15.3 1355
781 32.1
19.0 30.8 150 14.2 1256 907 34.5
Tons.
.78
Stephenson.
•77
Ditto
20.0
20.7 36.8 158 12.7
5 21.0 38.3 160 11.8
34.7 162 10.3 915
1128
1023 27.8
⚫83
Ditto
1084 37.0
.76
Ditto
1048 1129 36.0
.78
Ditto
5
6
22.1 42.5 160 10.6 930 1253 35.3
•78
Ditto
6
7
22.5 43.8
164 10.7 951
1292 37.2
•78
Ditto
8
9
22.7 45.5 163 9.6
23.3 51.0 163 9.0
853
1341 34.6 ⚫79
Ditto
8
1234SON∞
Miles.
23.45 50.5 7.2
35.00 46.3 5.6
19.57 34.6
31.14 36.0 6.1
12.12
32.5 9.2
Feet.
634
1312
493 1958
lbs. H.P.
25.2 •50
29.2
⚫37
7.2
634 1095
21.0
⚫39
537 1765
28.7
•20
810
678
16.6
•48
27.80 34.5 5.9
519
1555
24.4
⚫29
14.81 35.4 7.7
35.22 55.6 7.4
680 828
17 0
•51
655 2000
39.7
• 28
795
1503 36.2 +78
Ditto
11
12
13
24.4
10 24.0 53.5 165 7.8
23.8 58.0 161
23.6 59.8 167
64.7 164
690 1576 33.0
⚫80
Ditto
7.9 703 1709 36.3
.78
Ditto
14
15
16
22.75 43.6 160
17
24.75 60 40
160
6.5
18
24.75 70.40,
160
6.1
19
24.75 72.54 160 6.0
7.8 690 1763 36.8
Ditto
6.6 580 1907 33.5 • 80
Ditto
24.25 36.5 160 7.9 705 1076 23.8 ⚫85 Samuda.
23.75 42.5 160 7.8 700 1253 26.6 ⚫83
Ditto
8.0 716 1268 27.6 .83
Ditto
575 1825 31.3 .81 Mallet.
536 2075 33.8 .79 Ditto
Ditto
.78
527 2140 34.1
⚫79
Note (1)―The resistance due to friction and gravity in
the experiments on the Dalkey Line is calculated for an
incline of 1 in 115, instead of the actual gradient of 1 in
138, which allows 3 lbs. per ton for the friction from the
curve.
Note (2).-In estimating the power of the Engine on
the Whitstable Line no deduction has been made for the
friction.



EXPERIMENT No.1.
PLATE 3.
5
20
15
10
Atmosphere
Pressure of
No.1.
INDICATOR DIAGRAMS.
20
15
Mean effective Pressure 16.5 lbs. per Sq.Inch
от
5
Th
lbs.
18.0
10.0
17.6
6.0
2.0
18.3
2.9
Us.
10.0
21.0
20.9
3.8
18.0
2.4
21.7
2.2
18.6
2.3
21.8
2.2
18.6
2.3
91.8
2.2
18.6
2.?
21.8
2.2
18.6
2.2
21.7
2.2
18.4-
2.1
21.7
2.2
18.2
2./
18.0
No.2.
2.0
21.7
2.0
21.7
? j
18.0
2.0
21.6
1.9
17.9
2.0
21.5
1.8
17.8
2.1
UA
17.6
2.0
20.9
1.8
1.7
1.7
2-2
3.1
16.8
2.0
20.0
15.2
2.0
18.4.
12.7
2.0
15.9
11.8
2.2
14.0
10.0
3.2
13.0
5
20
15
10
Atmosphere.
Pressure of
20
15
Mean effective Pressure 13.4lbs per Sq. Inch
10
5
20
15
10
Atmosphere
Pressure of
lbs.
No.3.
17.0
9.0
4.5
18.5
2.7
17.8
2.0
19.8
2.1
19.4
2.2
19.0
2.2
19:0
2.1
19.0
2.0
INS
2.0
18.5
1.9
18.0
1.3
18, 2
1.7
18.1
1.7
18.1
1.6
17.9
1.6
16.9
16
15.1
1.6
13.1
1.9
11.6
3.0
10.9
บ
10
15
20
Mean effective Pressure 14.0 lbs. per Sq. Inch.



:
EXPERIMENT Nº2.
PLATE 4.
་
INDICATOR DIAGRAMS.
Atmosphere
The
Tressure of
5
10
15
20
lbs
11.0
Us
18.5
Amosphere.
Pressure of
5
10
15
20
18.7
4.5
3.1
21.0
2.5
7.8
22 Å
2.0
Uns
14.7
22.7
23.0
124.6
1.7
22.0
2.0
24.6
1
22.0
2.0
24.6
1.8
21.9
2.0
24.6
1.8
21.3
2.0
24.5
1.7
21.0
2.0
24.5
1.7
20.9 Z
1.6
20.7
No.2.
1.9
24.4 Z
1.9
24.5
No.1.
1.5
20.6
1.8
24.6
1.5
20.5
1.9
24.7
1.0
20.5
1.9
24.6
1.5
20.3
1.9
24.6
1.5
19.1
1.8
24.4
1.5
177
1.8
22.5
1.5
$5.6
1.9
18.8
1.8
13.8
2.3
17.0
12.9
16.3
5
10
Atmosphere.
Pressure of
lbs
3.4
ហ
10
15
20
Man effective Pressure 16.5 lbs. per Sq.Inch.
10
15
20
Mean effective Pressure 19.6 lbs. per Sq.Fich.
15
20
No.3.
W
lbs
Tbs
14.0
14.0
14.7
11.0
3.2
17.0
2.9
118.0
1.7
19.2
1.8
20.0
1.4
19.2
1.4
20.0
1.3
19 A
1.4
19.9
1.3
19.A
1.4
19.9
1.3
19.2
1.3
20.0
1.3
19.2
1.4
20.0
1.2
19.3
1.4
19.9
1.2
19.2 Z
1.3
20.0
1.2
19.2
1.3
20.0
1.1
19.2
1.2
20.1
1.01
19.2
1.1
20.1
1.0
19.2
1.1
20.0

1.0
18.8
1.1
19.8
1.0
17.9
1.1
18.5
0.9
16.3
1.0
17.0
0.8
13.8
0.8
14.5
0.9
12.3
0.9
12.7
2.0
11.6
2.0
| 11.0

ΟΙ
20
10
15
20
Mean effective Pressure 15.6 lbs. per Sq.Inch.
Meçon effective Pressure 16.0 lbs. per Sq." Inch.


Atmosphere
Pressure of
10
15
20
ì.
EXPERIMENT No.3.
PLATE 5.
No.1.
INDICATOR DIAGRAMS.
15
20
Mean effective Pressure 13.5 lbs. per Sq.Inch.
5
10
Atmosphere.
Pressure of
5
10
15.
20.
Atmosphere
Pressure of
10
15
20.
lbs.
16.
"Ubs.
13.0
4.5
16.0
3.0
10.0
3.5
2.0
12.5
2.5
6.0
13.0
16.5
2.0
13.7
2.4
17.0
2.0
14.9
2.4
18.6
2.0
14.9
2.4
18.6
2.0
14.8
2.4
18.7
2.0
14.8
2.4
18.7
2.0
14.9
2.3
18.7
1.91
14.9
1.81
114.9
No.2,
2.3
18.7
2.2
18.7
1.7
14.9
2.1
18.7
1.6
14.9
2.0
18.7
1.5
14.9
1.9
18.7
1.3
14.8
1.9
18.6
1.3
14.0
1.8
18.0
$.3
11.8
1.8.
15.9
1.3
10.5
1.8
13.9
1.5
9.2
2.1
12.2
2.0
8.5
3.0
11.5
15
20
Mean effective Pressure 10.5 lbs. per Sq.Inch.
10
Atmosphere
Pressure of
10
16
20
lbs.
11.5
4.0
2.7
10 5
1.9
1.6
2.0
13.4
1.9
13.6
1.8
13 5
1.7
13.5
1.7
18.5
1.8
13.6
17
13.6
1.6
13.6 Co
No. 3.
1.5
13.6
1.5
13.6
1.4
13.6
1.3
13.4
1.1
12.4
1.0
10.5
1.0
89
1.0
8.0
1.4
7.3

20
Mean effective Pressure 9.1 lbs. per Sq. Inch

10

t
}
}
EXPERIMENT No.4.
PLATE 6.
INDICATOR DIAGRAMS.
Mean effective Pressure 1/4.8 lbs. per Sq.Inch.
{tinosphere,
Pressure of
5
10
15
20
lbs.
Atmosphere.
Pressure of
5
10.
15
20
8.2
5.5
9.5
lbs.
7.3
2.3
5.8
2.4
8.6
2.0
12.0
2.0
15.0
2.0
13.2
2.0
17.0
2.1
14.8
2.0
19.5
2.1
15.8
2.0
19.8
2.0
15.8
2.0
19.8
2.1
15.9
2.1
19.9
2.2
16.0
2.1
19.8
2.1
16.0
2.0
16.0
No.2.
2.0
1.9
19.9
19.8 Z
No.1.
1.9
16.0
.1.7
19.9
1.8
16.0
1.7
20.0
1.7
15.9
1.6
120.0
1.6
16.1
1.5
20.0
1.5
15.5
1.5
19.0
1.51
12.5
1.5
16.6
1.4
11.2
1.6
14.6
1.4
9.8
1.6
12.9
1.8
9.1
2.1
12.2
10
15
30
10
15
20
Macon effective Pressure 14.2 lbs. per Sq. Frch.
5
Atmosphere.
Pressure of
10.
15
20
No.3.
lbs.
8.5
5.0
1.8
6.7
1.5
11.4
1.6
12.9
1.6
14.6
1.6
14.8
1.6
14.9
1.6
15.0
1.5
15.0
1.5
15.0
1.4
14.9
1.3
14.9
1.8
14.9
1.2
14.8
1.1
14.8
1.0
13.6
0.9
11.5
0.9
9.8
0.8
8.8
0.9
8.4
15
20
Mecon effective Pressure 10.9 lbs. per Sq.Inch.


5
10

PLATE 7.
EXPERIMENT No. 5.
25
20
15
10
5
Atmosphere
Pressure of
INDICATOR DIAGRAMS.
No.1.
7bs
Tas
11.1
4.2
11.0
4.0
2.7
4.0
3.4
11.9
3.6
Ths
5.2
4.5
12.7
3.4
11.9
3.7
14.4
3.5
11.9
3.7
14.8
3.5
13.4
3.6
16.2
3.5
13.8
3.6
16.6
3.5
13.8
3.6
16.7
3.5
13.8
3.6
16.8
3.4
13.8
3.2
13.7
No.2.
3.4
16.7
3.3
16.8
3.0
13.7
3.1
16.8
2.9
13.7
2.9
16.9
2.7
13.8
2.8
17.0
2.4
13.8
2.8
17.0
2.3
13.3
2.8
16.8
2.3
11.0
2.9
4.5
2.3
8.9
2.9
11.4
10
2.31
2.7
20
Mean effective Pressure 8.0 lbs. per Sq." Inch.
8.6
2.9
11.3
7.8
3.9
10.3

ST
25
15
20
Mean affective Pressure 10.4lbs. per Sq'Inch.

25
20
15
10
5
Atmosphere
Pressure of
EXPERIMENT No.6.
PLATE 8.
20
15
10
5
Atmosphere
Pressure of
LO
No.1.
INDICATOR DIAGRAMS.
20
15
10
Tbs.
.0
5.5
2.2
Ꮄ .5
1.5
13.6
1.5
16.2
1.5
16.9
1.6
17.0
1.7
17.2
1.7
17.2
1.6
17.2
1.5
17.2 Z
1.4
17.2
No.3.
1.3
17.2
1.2
17.2
1.2
17.2
1.1
17.0
1.0
15.5.
1.0
13.4
0.9
11.4.
0.9
10.3
1:3
9.6
Atmosphere
Pressure of
lbs.
$.1
5.7
8.1
2.3
13.t
2.2
1.6
14.1
1.8
1.8
15.4
1.8
1.8
17.0
1.8
}
lbs.
7.9
70.0
16
16.
19.0
20.9
1.8
17.3
1.8.
21.0
1.8
17.3
1.8
21.0
1.9
17.3
1.8
21.1
1.8
17.3
1.8
21.2
1:8
17.3
1.7
17.3
No.2.
1.9
21.2
1.8
21.1
1.6
17.3
1.7
21.1
1.5
77.3
1.7
21.0
1.4
17.3
1.7
21.1
1.3
17.2
1.6
21.0
1.2
15.5
1.6
20.6
1.2
13.4
1.6
17.4
1.3
11.4
1.6
15.3
1.3
10.5
10
1
9.7
Mean effective Pressure 13.0 lbs. per Sq. Inch.
1.7
13.7
2.2
12.9
15
20
10
20
Mean effective Pressure 16.1 lbs. per Sq.Inch
20
15
10
Atmosphere.
Pressure of
20
15
Mean effective Pressure 12.9Ths. per Sq. Inch.


10
5

EXPERIMENT No. 7.
INDICATOR DIAGRAMS.
10
Atmosphere
Pressure of
5
10
15
20
Atmosphere
Pressure of
5
10
15
20
The
8.0
2.7
8.0
lbs
4.0
2.6
5.0
2.6
4.8
2.5
9.1
2.5
10.0
2.6
13.3
2.5
12.4
2.7
14.0
2.5
74.8
2.7
14.0
2.6
15.0
14.3
7
2.7
15.3
2.7
14.5
2.6
15.6
2.5
14.6
2.5
15.6
2.4
14.6
2.4
2.3
14.7
No.2.
2.2
14.7
2.2
2.3.
15.7
15.7
No.1.
15.8
2.01
14.7
2.0
15.8
7.8
14.7
2.0
15.8
1.71
14.7
1.9
15.7
1.7
14.0
1.8
15.2
10.8
1 . 2
11.1
1.7
10.0
2.0
11.0
1.7
9.0
2.1
10.1
2.4
SA
10
15
20
Mean effective Pressure 9.5 lbs. per Sq.Frich.
2.9
10
15
20
Mean effective Pressure 10.3lbs.per Sq." Inch.
9.1
Atmospheres
Pressure of
15
20
tas
PLATE 9.
3.5
2.7
4.6
2.7
8.6
2.7
11.8
2.7
13.1
2.7
13.2
2.7
13.3
2.7
13.5
2.6
13.5
2.5
13.6
2.3
13.6
No.3.
2.2
13.6
2.0
13.5
2.0
5
1.9
13.7
1.8
13.0
1.7
10.0
1.7
9.1
1.8
8.4
2.3
7.5
10
15
20
Mean effective Pressure 8.6 lbs. per Sq." Inch.



PLATE 10.
EXPERIMENT No.8.
No.T.
INDICATOR DIAGRAMS.
Atmosphere.
Pressure of
01
5
10
15
20
25
30
35
Atmosphere
Pressure of
10
15
20
25
30
35
Us
Thi
25.9
30.8
30.8
22.4
19.3
17.5
22.7
8.1
8.0
22.6
5.9
5.0
UAS
29.7
27.2
27.4
27.4
27.4
22.6
3.8
3.6
27.4
22.4
3.7
3.6
27.3
22.2.
3.6
3.6
27.0
22.0
3.6
3.6
26.5
21.8
3.61
3.6
26.1
21.6 Z
3.6
6명
​21.5
3.7
No.2.
3.6
25.8
3.6
225.8
21.4
3.7
3.7
25.8
21.3
3.9
3.7
25.8
21.1
4.0
3.7
25.6
21.0
4.2
3.8
25.5
20.8
4.3
4.0.
24.9
20:4
4.7
4.2
23.3
19.0
5.0
4.4.
20.0
16.6
6.8
5.7
17.6
14.8
8.8
7.0
10
20
25
30
35
10
15
20
25
30
35
Mean effective Pressure 14.8 lbs. per Sq." Inch.
Mean effective Pressure 18.9 lbs. per Sq."Buch:
No.3.
Atmosphere.
Pressure of
10
15
20
25
30
35
los
Atmospheres
Pressure of
5
10
15
20
25
30
35
Tos
20.0
26.7
21.7
24.0
21.0
19.8
15.5
14.0
21.0
19.7
6.5
5.2
21.0
19.7
3.8
3.2
21.0
19.7
2.3
2.3
20.8
19.6
2.5
2.0
20.5
19.3
2.5
2.0
20.3
19.2
2.5
2.0
20.1
18.8
2.5
2.0
20.0
18.7 6
2.5
2.0
19.8
18.5
2.4
2.0
19.8
18.5
2.4
2.0
18.4
2.4
19.7
2.0
18.4
2.5
19.7
2.0
18.3
2.7
19.7
2.2
19.5
18.0
2.8
17.4
2.8
18.7
2.3
2.3
3.0
4.
16.5
2.9
77.18
15.3
14.2
3.7
13.7


12.4
10
20
26
30
Moan effective Pressure 14. 1 lbs. per Sq. Inch
35
10
15
20
25
30
35
Mean effective Pressure 14.6 lbs. per $q?.
Inch


1
EXPERIMENTS WITH ROPE ONLY.
No. 1.
5
10
Pressure of
Atmosphere.
5
10
5
10
Us
The
3.0
ก
2.9
This
4 0
18.
2.0
0.8.
0.9
1.0
0.2
2.0
0.8
3.2
1.9
1.9
6.0
2.0
7.3
1.9
8.6
2.0
8.8
1.9
8.7
1.8
$.8
17
8.8
No. 2.
1.7
8.9
1.5
$.9
1.4
8.9
1.3
9.0
Moon effective Pressure 1.9lbs. per Sq¹ Inch.
2.0
5.7
2.1
6.9
2.1
8.2
2.1
2.0
8.9
2.0
ول
1.9
9.1
1.8
9.2
1.7
9.2
9.4
1.4
9.4
1.2
9.0
9.3
1.2
7.8
7.2
8.2
1.2
5.5
1.2
6.1
1.2
5.0
1.3
5.7
1.4
4.8
1.6
5.2
Mean effective Pressure 4.8 lbs. per Sq² Inch.
5
5
10
INDICATOR DIAGRAMS.
No.3.
10
10
5
Tbs
Ubs
6.0
2.21
242
Ubs
Tas
1.0
6.0
3.0
0.0
02
2.0
2.0
3.0
2.41
2.3
7.0
6.0
2.0
6.5
2.3
7.3
2.3
8.0
2.2
8.0
2.2
8.0
2.1
8.0
2.1
8.0
No. 4.
2.0
18.0
1.8
8.0
1.6
8.0
1.4
8.0
Mean effective Pressure 4.6 lbs. per Sq Inch.
2.1
17.5
2.1
8.0
2.2
18.4
2.2
8.6
2.1
8.6
2.0
8.5
1.8
8.5
1.7
8.5
7
18.5
1.6
8.5
1.4
8.5
1.2
7.8
1.2
8.0
1.1
16.0
1,0
6.0
1.1
4.2
1.0
4.9
1.0
4.0
1.0
4.5
1.1
3.8
1.1
4.0
10
10
Atmosphere.
Pressure of
5
Mean effective Pressure 3.9 lbs. per Sq. Inch.
Atmosphere.
Pressure of
LO
5
No. 5.
Tas
Tbs
ш
5.0
6.
2.4
1.3
Reyths of
2.4
Engine.
2.5
4.5
Berns of Engine
por Minute.
Speed of Piston
in Fert Min.
per
Mean effective Pressure 2.5 lbs. per Sq! Inch.
2.6
5.5
2.7
5.6
2.7
6.5
2.6
7.1
2.5
7:1
2.4
7.1
2.3
2.1
7.0
2.01
17.0
8
7.0
7.0
་--
7.0
10
Started Engine 0.0
1.49
PLATE HI.
3.7

1.3
1.2
Horse Power
1.2
1.8
60
2.56
100
} Diagram No. 1.
35.8.
358,0
17.7
3. AD
130
10.16
8.47
7.5+
6.51
4.59
170 S
Diagram No. ?
34.2
235
275 Diagram No. 3..
38.0.
380.0
342.0
16.6..
..17.7..
370
310
Diagram No. 4.
40.A.
404.0.
15.9..
12.1
12.48
480
445
} Diagram No. 5.
44.6.
446.0.
13.0
Mean 16.1
5
10

¡
ATMOSPHERIC RAILWAY SYSTEM.
33
Mr. JOSEPH SAMUDA must be permitted to say, that he thought the
author of the paper had scarcely entered fairly into the examination
of the system, as the statement was made up entirely of the demerits
of the plan, without giving it credit for the success, which had
already attended its first establishment. Several of the objections
were made, evidently without a knowledge of how the apparent
difficulties in the application, were proposed to be overcome, or were
actually avoided. He would instance only a few points, and leave to
others, better qualified than he was, the task of refuting the charge of
impossibility.
It was not proposed to use any other than the engines of the main
line, for working the sidings, which could be laid in, without at all
interfering with the continuity of the main line. Level crossings
were quite as practicable as on locomotive lines. There was even
an additional security, as by a simple contrivance, consisting of a
cylinder and piston connected with the main pipe, the platform,
which, when down, formed the protection of the valve, under the
crossing, could be raised when the vacuum was being formed, and
thus, not only became a signal that a train was about to pass, but
also formed a barrier, for preventing anything from traversing at an
inopportune moment.
He could not understand the necessity for bringing two trains
together, as had been assumed; but if that did occur, a little extra
power might be used in that particular instance, in the same way as
in an emergency, another locomotive would be added to the ordinary
train engine.
As respected the liability to be thrown off the rails by impediments,
he must contend, that the position assumed was not supported by facts.
On the Dalkey line, there were curves of 130 yards radius, which
were constantly traversed at a speed of 35 miles per hour; yet no
accident had occurred. It was well known, that locomotive engines
were not in the habit of traversing curves of that radius, at such a
speed.
He could not agree with the statement of the comparative cost of
the two systems. He thought, that the author had underrated the
actual cost of locomotive haulage; while he had overrated, not only
the cost of that by the atmospheric system, but also the amount of
power employed; for instance, with a gross load of 75 tons, not more
than two-thirds of the actual power of the engine were employed, as
was shown by the indicator diagrams.
In the statement of the cost of construction, Mr. Samuda's expe-
rience was equally at variance with the assertions of the author.
As regarded the probable expense of the maintenance of the way,
on new atmospheric railways; it must be remembered, that the
34
ATMOSPHERIC RAILWAY SYSTEM.
Dalkey line was quite new, but it had worked through the winter
without any stoppage, either from subsidence, or from slips, and
it was kept in order with as little difficulty as the part which was
worked by locomotive engines.
It should not be assumed, that the system was not susceptible of
modification, to accommodate itself to any amount of traffic. Mr.
Samuda must, on the contrary, assert, that any economical arrange-
ments which were practicable with the locomotive system, might be
adopted with the atmospheric plan. For instance; if it was found
desirable to have trains at long intervals, the obvious plan would be,
to substitute, for a powerful engine, a small power, to pump water
into a reservoir, which, during the time necessary for forming the
vacuum, should exert a considerable power upon a water-wheel.
The system was capable of being economically adapted to almost any
locality, where there was sufficient traffic to warrant the formation of
a railway.
Mr. P. W. BARLOW stated, that his object in presenting the paper
to the Institution, was not to attack the atmospheric system, but
simply to suggest, for the consideration of the members, certain ob-
jections with reference to it, which appeared to him proper subjects
for discussion.
As to the sidings, he did not contend that it was impossible to
apply them, in a mechanical point of view; but that they would lead
to great inconvenience, and be inconsistent with practice. It could
only be done, (unless the crossing were divided,) by raising the
piston above the level of the rails, which would be inconvenient, from
want of space under the carriages.
With reference to the comparative advantage of obtaining 10 miles.
of pipe in one length, it would be desirable in one respect, as per-
mitting a less number of stationary engines, and as saving working
expenses; but it would be objectionable, inasmuch as it would
increase the loss of time which necessarily occurred, when the trains
met on a single line, from the time requisite to exhaust the air out of
the pipe to the next station, which would require 20 minutes.
Mr. PIм professed a high respect, not only for the speculative
views of the theorist, but also for the examination of the practical
man, but he thought the theory of subjects like the present,
should not be examined, until after careful observation of the actual
practical working of the system, as it was notorious how the results
of the soundest theory were modified by a slight alteration in the
practical condition of the machine, or system. It was to be regretted,
that the author had not made himself better acquainted with the
results obtained on the Dalkey line, where any information he re-
quired, would have been readily afforded to him. He would then
ATMOSPHERIC RAILWAY SYSTEM.
35
have seen, that several of his objections did not, in fact, exist.
would suffice to mention a very few.
It
The leading carriage being tied down to the line, by its connexion
with the piston, was sufficient of itself to prevent any tendency to run
off the rails, even on the sharpest curves. On one occasion, owing to
the carelessness of an attendant, the leading carriage, with the piston,
became detached from the train, and travelled up to Dalkey in perfect
safety, at a velocity of nearly 70 miles per hour.
There were many omissions in the paper, which savoured some-
what of a strong bias against the atmospheric system. The degree
of speed which could be attained, with such safety, was not noticed.
There was not a word as to avoiding the chance of collision, when it
was notorious, that a collision was utterly and physically impossible.
In stating that the dimensions of the tunnels were regulated by the
height of the pile of goods on the luggage trains, it did not appear to
have struck the author, that it was possible to reduce that height, and,
at the same time, to carry as great a load in a more advantageous
form. Mr. Pim was of opinion, that the introduction of the atmos-
pheric principle would produce an entire change in railway traffic,
as it would be found, that frequent and light trains were more advan-
tageous, both to the railway Company and to the public, than heavy
trains at long intervals. The public would very soon have an oppor-
tunity of judging practically as to the merits of the system, and his
confidence in its advantages was not at all shaken by the statements
he had heard in the paper. On the contrary, he had much more
confidence in the results, which he felt assured would be attained, by
the skill of the two able engineers who were then constructing lines
on the atmospheric system.
Mr. P. W. BARLOW said, the practical results of the working on
the Dalkey line showed, that the tractive power of the stationary
engine, as applied by the atmospheric pipe, was about equal to that
of an ordinary goods engine used on railways; or the same amount
of work could be performed in the same time by one of those engines,
and that the consumption of fuel, during the actual motion of the
train, was at least equal to that used by the locomotive, which was
40 lbs. per mile; consequently, with the loss from obtaining the
vacuum, and constantly keeping up the steam of the stationary
engine, no economy in working could be obtained, under any circum-
stances, unless greater perfection were obtained in the application of
the atmospheric principle; and it was doubtful if the Dalkey line,
with its advantageous incline and numerous trains, could not be more
economically worked by locomotive engines.
Mr. C. H. GREGORY said, that without wishing to depreciate Mr.
D
36
ATMOSPHERIC RAILWAY SYSTEM.
Barlow's interesting paper, there were some points in it, not noticed
by previous speakers, which he would submit, required correction.
Mr. Barlow had stated, that in the comparison he had instituted, the
atmospheric engine had consumed 40 lbs. of fuel per mile, and that
an equal weight was consumed by a locomotive goods engine, under
similar circumstances; but it did not appear that any allowance had
been made, by him, for the difference in cost, between coal used in the
atmospheric and coke in the locomotive system. He thought too,
that a comparison between the two systems, ought to include a notice
of the great difference between the wear and tear of locomotive and
stationary engines, which would be much in favour of the latter. The
comparison had been made between the working of the two systems
at a slow speed, which he believed was not so favourable to the
atmospheric system, where a greater speed would show comparatively
greater economy, while it was well known, that high velocities induced
a great loss of power in locomotive engines. In illustration of this
fact, he alluded to some indications which had been taken by M. Gouin,
a French engineer, in the cylinders of locomotive engines at different
velocities. In these it was shown, that when the engines were
running at slow speed, nearly the whole pressure of the steam had
been effective in the cylinders; while, at high speeds, the indications
showed a loss in the cylinders alone, amounting to about 50 per cent.
of the pressure. This result was in addition to all the acknowledged
mechanical defects of locomotive engines at high velocities.
Mr. P. W. BARLOW explained, that he did not contend that high
velocities could not be obtained on short lines, or between stations;
but on long lines, when the trains met, each train must wait, until the
air was exhausted out of the next length of pipe, which would reduce
the speed, in practice, to 20 miles per hour.
Mr. I. K. BRUNEL did not appear either as a supporter of the
atmospheric system, or as wishing to condemn it; but he thought it
due to the inventors, that those who were about to use it should not be
entirely silent. The paper appeared to him, rather a list of objections.
to the plan, than an examination of its comparative value as a method
of propulsion; and he must say, that these objections did not seem to
be supported by calculation, or by argument. Mr. Brunel was quite
prepared to admit, that there were many situations to which the system,
in its present state, was inapplicable; but, as a practical man, he
clearly perceived the manner of remedying many of the alleged
defects; and, without that feeling, he should have had considerable
hesitation in recommending its adoption. He thought, also, that
many of the presumed deficiencies did not really exist; for instance,
upon the atmospheric line, now being established in Devonshire,
ATMOSPHERIC RAILWAY SYSTEM.
37
there would be numerous stations, in which he anticipated doing all
the station work, with as much facility as with locomotives, and even
more conveniently.
He did not anticipate any difficulty in transmitting special trains
and expresses, but, on the contrary, he believed that the impossibility
of collision would induce peculiar facility in that respect.
He thought, that instead of the stoppages reducing the average
speed below that of locomotives, say to 20 miles per hour, double
that speed would be certainly attained.
He could not agree, that because the system had hitherto only been
practised on a short line, it was inapplicable to long lines; calcula-
tions proved the reverse, and it would be only just to await the result
of the practical working of the lines, now in course of execution.
He was of opinion, that by the use of large boilers, fixed on the most
approved plan, by husbanding the power, working the steam expan-
sively, and using the present known improvements in stationary
engines, the system would prove as economical, as it was free from
danger.
Mr. CUBITT, V. P., thought, that any assertions as to the capa-
bilities or powers of the system, were, in its present state, very incon-
clusive, and scarcely fair, and the best manner of confuting the
positions of the paper was to have a line at work, which would, he
hoped, be accomplished without much delay. He must, however, be
permitted to say, that the mechanical difficulties of the level crossings,
The real ques-
sidings, &c., were met by simple mechanical means.
tions were the first outlay, and the cost of working, and they could
only be decided by actual experience.
Mr. JOHN SCOTT RUSSELL was neither a prejudiced adversary, nor
a headlong advocate, of the atmospheric system. He agreed in the
opinion already expressed, that any discussion on points which were
soon to be submitted to the test of experience, was of comparatively
small value. One important service, however, had been already
rendered by the discussion, in having elicited the statements of two
eminent engineers, who were then engaged in carrying out the prac-
tical application of the atmospheric principle on a large scale. They
had stated, that all those difficulties, which had been mentioned in
the paper, had been foreseen by them, and had been conquered. This
fact was important, for it was most desirable, that any opposition to
the atmospheric system should be based on right grounds, and not
upon mere prejudice. The paper had pointed out, with much ingenuity,
the minor practical difficulties in the way of the execution and
the use of the atmospheric railway; but these he did not at all regard
as objections to the system, but merely as the statement of pro-
D 2
38
ATMOSPHERIC RAILWAY SYSTEM.
blems, of which the ingenuity of the promoters, in constructing the
works, had to invent the solution. Now he thought it only fair to
say, that seeing the atmospheric system in the hands of such mecha-
nics as Mr. Cubitt and Mr. Brunel, he had no hesitation in expressing
his conviction, that they must have seen their way clearly to sound
practical solutions, for all their mechanical difficulties, or they never
would have risked their reputation on the construction of such lines.
Although he was himself much inferior to them as a mechanic, he
could see his way clearly, to the solution of many of the difficulties
stated in the ingenious paper of Mr. Barlow, and he had such faith
in the powers of invention of the engineers of this country, and in the
mechanical skill and powers of execution of the workmen, that he
had no doubt if the atmospheric system was sound at heart, and in its
principle, all these minor evils would disappear.
On the faith, therefore, of the talent of these engineers, he would
give the system credit for all that their skill could devise, and he
had no doubt they would overcome the mechanical difficulties of
practical execution. But there remained the great question of
the value of the system, as a general system of traction, applicable
on all railways, and capable of superseding the locomotive engine.
It was on this general ground, that the question must be decided,
and here the result, he thought, was perfectly clear. The atmospheric
system was merely one among many modifications of stationary
power. As such, while it possessed the advantages, it must encounter
all the evils of the stationary system, and on this broad ground, that
the stationary system was neither so economical, nor so convenient,
as the locomotive system, he rejected the proposition of the inventors,
who wished to substitute stationary atmospheric, for locomotive engine
power, generally, on railroads. But in justice to the system, and to
those who had adopted it, he ought to say, that he had no doubt, that
in cases where stationary power was desirable, there were circum-
stances which might render the atmospheric system peculiarly ap-
propriate. Selecting, for instance, a line where there were many
or sharp curves, or many inclines of variable and steep gradients,
and where also the trains were numerous, uniform in magnitude and
number; such a case was most favourable to stationary power, and to
the atmospheric system especially. He thought it would have been
wiser, if the inventors of the system had brought it forward as an
expedient of this kind, suited to these circumstances, rather than as
a revolutionary system, proposing to displace locomotives on all the
great railways of the country. In that case, they would have received
the support of many, who now could not accord with their views. In
that modified application he would be happy to see it successful, and
ATMOSPHERIC RAILWAY SYSTEM.
39
he thought the wiser promoters of the system were of his opinion, for
it was in peculiar circumstances, of the nature he had indicated, that
they were about to introduce it. He should be glad to learn from
those engineers who were about to introduce the system, whether they
would assure him, that in the application of the system, there was no
loss incurred in the use of the air as the means of applying the power.
He conceived there must be a mechanical loss of power, in the pro-
cess of first rarifying the air and afterwards coudensing it.
Mr. PIм said, that it was not for him to enter into an analysis of
the theory of the atmospheric system, but his belief in its correctness
was in a great degree confirmed by the investigation of Dr. Robinson
of Armagh, who had arrived at diametrically opposite results from
Mr. Russell.
3
He could, however, judge of the practical results; and when com-
paring the actual speed and cost of propulsion on the Dublin and
Kingstown railway, with that of the Kingstown and Dalkey line, the
result was decidedly in favour of the latter; on the former, with
locomotive engines, mile with a rise of 13 feet, was traversed in 4
minutes; while on the latter, with the atmospheric system, 1 mile with
a rise of 71 feet and several sharp curves, was passed over in a little
more than 3 minutes: the consumption of steam in the Dalkey engine
was, at the same time, much less than in a locomotive.
4
Mr. CUBITT, V.P., thought, that it was not incumbent on the
advocates of the system to show, that it was perfect as a mechanical
power. It sufficed to show, that it was superior to fixed engines and
ropes, which had been attempted to be substituted for locomotives,
not only on account of their cost of steam and fuel whilst travelling,
but also because of their excessive wear and tear.
If, as had been asserted by a great railway authority, the power
required to move the engine and tender, equalled that requisite for
drawing fifteen passenger carriages, which was more than an average
train, it would follow, that it would cost more to move the engine and
tender, than the average of all the passenger trains. If therefore the
traffic could be conveyed by the atmospheric system at a less expense,
a great point would be gained.
Mr. J. Scorт RUSSELL gathered from what Mr. Pim had said,
that it appeared from Dr. Robinson's calculations, that the power
expended and the power usefully applied, were theoretically precisely
equal. Mr. Russell had not arrived at the same conclusion, and he
would desire to ascertain, whether the engineers intending to use the
system and who had doubtless examined the subject carefully, agreed
with Dr. Robinson's view, or entertained a more modified opinion of it.
Mr. J. SAMUDA could not admit Mr. Russell's view of the loss of
*
40
PORTEOUS' SIGNAL WHISTLE.
power. He contended, on the contrary, that the power primarily
expended in forming the vacuum, was returned during the passage
of the train. When the air-pumps were working at 15 inches of
mercury, with a pressure of 4 lbs. per square inch on the piston of
the steam cylinder, a power was attained in the pipe, equal to 7½ lbs.
per square inch upon the travelling piston.
Mr. I. K. BRUNEL contended also, that a loss of power to the
extent that had been stated, could not be proved, when a certain
amount of work was performed, with the expenditure of a certain
power. He would admit, that some loss might arise from the
absorption of heat, during the process of rarefying the air in the
main, but he could not concur in the position assumed by Mr. Russell.
PORTEOUS' SIGNAL WHISTLE FOR RAILWAYS.
Mr. PORTEOUS exhibited an instrument introduced by him for
the purpose of giving signals on railways, and for other purposes.
ท
FORTEOUS PATED
The instrument consists of three, or
more, metallic tubular whistles, com-
bined under one mouth-piece, and having
their tones so arranged, that by the in-
troduction of one discordant note, an ex-
tremely shrill vibrating sound is pro-
duced, which strikes forcibly on the ear,
and can be heard at a great distance.
Its peculiar discordance enables it to be
readily distinguished from any ordinary
whistle, however powerful, and from any
common sound. Its tone somewhat re-
sembles that of the steam whistle used
on locomotive engines, and on that account it is found very useful for
persons employed on railways.
They have been made of all sizes, and are adapted not only for
railway purposes, but for park and gamekeepers,* the police, and for
any position where a prompt signal is required.
They appeared, from the testimony of several members, to have
been generally approved upon the railways where they had been
introduced.
Messrs. Swaine and Isaac, 185, Piccadilly, who are the sole wholesale
agents, have adapted them generally for sporting purposes, for which they have
the patronage of H.R.H. Prince Albert.

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