THE PROPOSED ATLANTIC AND PACIFIC SHIP
RAILWAY.
NO. I.
( From " Ikon," London, September 5, 1884.)
Connecting the United States and Mexico with South America
is a neck of land, not very long, nor in some parts very wide, and
through which it has been the desire of civilised nations, for a
great many years past, to cut a canal, in order to unite the At¬
lantic and Pacific Oceans. A glance at the map at once points
to the desirability of effecting this union, which would straight¬
way afford a short and direct passage from Europe and the United
States to the western shores of America, Australasia, and China,
and vice versa. The great object is, of course, to obviate the
necessity for the transhipment of goods and passengers ; and the
schemes which have been brought forward have been mainly for
canals. Railways, of course, have been proposed, and a com¬
mencement has been made on the works of the Panama Railway.
But the fundamental objection to a railway is that the necessity
for transhipment arises, and this is in every way undesirable, or,
to put it plainly, objectionable. The projects which have had for
their object the cutting of a ship canal through the American
isthmus have been numerous. The establishment of inter-oceanic
communication by this means has been proposed by various routes
trending from north-west to south-east, and including those of
Tehuantepec, Honduras, Nicaragua, Chiriqui, Panama, Chepo,
and Atrato. The Tehuantepec route, which is the most northern
and western, appears to have attracted- the attention of Cortes,
soon after the conquest, from the narrowness of the isthmus, and
the remarkable depression of the table-land at that point. The
idea of opening a canal between the two oceans by this route,
which had long been entertained, received a sudden impulse in
1771 from the unexpected discovery in the fort of San Juan de
Ülloa, in Vera Cruz harbour, that some cannon cast at Manila
had crossed the isthmus by the rivers Chimalapa and Coatza-
coalcos. Surveys of this route were subsequently made by Don
Augustin Cramer in 1774 ; by Don Tadeo Ortiz and Don Juan de
Orbegoso in 1824 J by Señor Moro in 1842 and '43 ; and in 1852
by Mr. J. J. Williams, on the part of the Tehuantepec Railway
Company of New Orleans. In the year 1842 General Santa Anna,
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2 ig?*
the then President of Mexico, granted Don José de Garay permis¬
sion to cut a canal across the isthmus of Tehuantepec, and a sur¬
vey was at once commenced under the orders of Garay, and at his
expense. According, however, to the report of Mr. Williams,
who made his survey in conjunction with Major Barnard, of the
United States Topographical Engineers, water does not exist at
the requisite level in sufficient quantity to render a canal practica¬
ble. More than a century of wishing, scheming, and surveying
have thus failed to bring about the desired end, and in the face of
the report just referred to the formation of a canal may be con¬
sidered to be as near or as remote now as when the geological
development of the isthmus was completed.
But there is one way out of the difficulty which of course ap¬
pears, like many other things, very simple when known. This is
to transport ship and cargo bodily overland from one ocean to the
other across the Mexican isthmus. The idea is a bold one, but
it is nevertheless a feasible one, as will presently be seen. The
proposition is due to Mr. James B. Eads. of the United Stages.
The idea is not one of yesterday, for it is now more than four
years since Mr. Eads first conceived the notion of a ship railway.
When the British Association was holding its jubilee meeting at
York in 1881, Mr. Eads communicated to Section G an outline of
his scheme as stated by us at the time. Since then he has been
engaged in having surveys made, perfecting the details of his
scheme, and in bringing the matter before the Congress of the
United States, in order that his own government might have the
opportunity of aiding it in the interest of American commerce.
In 1881, Mr. Eads obtained from the Mexican government a con¬
cession, which extends over a period of ninety-nine years from
its date. This concession authorises the construction across the
Isthmus of Tehuantepec of a ship-railway, an ordinary railway,
and a line of telegraph. There are other important provisions,
such as exempting ships and merchandise in transit from govern¬
ment duty, granting the concessionaire a million acres of public
land, and guaranteeing protection during the construction and
subsequent operation of the works. Having obtained the conces¬
sion, Mr. Eads set about having the necessary surveys made, and
he at once placed two parties in the field, one under the direction
of Mr. Williams (who made several former surveys on the Isthmus),
and another party under the direction of Mr. E. L. Corthell, the
chief engineer of the West Shore Railroad, in the State of New
York. At the same time a third party of engineers under the di¬
rection of Don Francisco De Garay, an able Mexican engineer,
with forty assistants and men, was detailed by the Mexican gov¬
ernment to assist Mr. Eads in making his survey. Two lines
were run by these parties through the mountain region. The
river and its bar were carefully surveyed and sounded by Mr.
Corthell from the sea to Minatitlan. The harbours on the Pacific
3
were inspected at the same time by him. These partial surveys
established the fact beyond question that it was entirely practica¬
ble to construct the ship-railroad entirely across the isthmus.
Surveys under Mr. Martin Van Brocklin, who had four parties in
the field, were made a year' later. Connectêd instrumental sur¬
veys from Minatitlan to Bocea Barra and to Salina Cruz have been
recently completed under his personal direction. A still better
line than that of either Williams or Garay has been found on the
isthmus. Having prepared matters sufficiently for the purpose,
Mr. Eads submitted the matter to Congress, and the consideration
of the affair was referred to the Committee on Commerce of the
United States Senate. After having taken a considerable amount
of evidence, and after having very carefully considered the whole
question in all its bearings, the committee made, by a unanimous
vote, a favourable report to the Senate recommending that the
bill should be passed in the interests of the country. The Senate
having failed to take any action upon this report, Mr. Eads with¬
drew his proposition to the United States government from the
further consideration of Congress, and he is now in England with
the object of bringing his project before the public. Mr. Eads
having personally communicated to us the details of his project,
we have much pleasure in promoting the object he has in view
by placing full particulars before our readers. In doing so, we
shall deal with the subject in three articles. In the first—the
present one—we confine ourselves to historical and general par¬
ticulars, and a description of the route ; in the second, we shall
describe in detail the harbours, docks, railway, and the transport¬
ing plant ; whilst in the third, we shall enter into the commercial
considerations affecting the question.
The ship-railway as now proposed will be about 134 miles in
length. Commencing from the Atlantic side, the route will start
from the Gulf of Mexico, and the Coatzacoalcos river will be uti¬
lised to Minatitlan, about 25 miles distant from the gulf, in which
the tide has a rise and fall of 18 inches only. For the first 35
miles from Minatitlan the route extends over an alluvial plain
composed in all its lower portions of a heavy tenacious clay. In
the higher portions, and in the small ridges, a clay loam is found
with an occasional deposit of sand. Upon this portion of the line
there is but little large timber, but the surface generally is covered
with luxuriant undergrowth. Leaving this plain the line enters
an undulating table-land extending to a point 25 miles from Min¬
atitlan, where it leaves the valley of the river and follows a suc¬
cession of broad valleys between which there are extensive table¬
lands with no high or permanent dividing summits between them.
The whole forms an extensive interior basin having a gentle in¬
clination towards the summit, and bordered on its eastern and
western sides by irregular mountain ranges, spurs of the main
Cordilleras that run through the entire continent, and which make
4
at this point one of the most marked depressions to be found in
its whole length. From this basin the line passes through a val¬
ley, formed by a small stream, to the plains of Tarifa, which con¬
stitute the summit of the line, 736 feet above low tide. Crossing
these plains the line reaches the pass of Tarifa, the lowest and
most accessible of the many passes through this general depres¬
sion in the main mountain chain. From the Tarifa Pass (or the
"Portillo," as it is called) the line descends to the Pacific plains,
reaching them 118 miles from Minatitlan by a uniform gradient
following a succession of valleys through the intervening foot
hills. The heaviest excavations will be in cutting through the
spurs of the hillsides, or through divisions between adjacent val¬
leys, but no exceptionally heavy work of this kind is required
throughout the entire route. Across the Pacific plains the line
can be carried in almost any desired direction, the surface being
remarkably even and uniform in character. On the Pacific side
there is the choice of two harbours—namely, Salina Cruz and Bocca
Barra. The latter would appear to have many advantages over
Salina Cruz, and there, moreover, the Pacific tide has a rise of
only 5 feet. There are no important engineering difficulties in
the way of deepening Bocca Barra, which is the outlet of two
large lakes, and bringing ships through the lake to its northern
side, by which twenty-five miles of railway would be saved over
the route to Salina Cruz. It is upon the route to this terminus
that the estimates of Mr. Eads have been made. The maximum
gradient required to reach the summit from either direction is 1
per cent., or 52.8 feet per mile. On the Atlantic side the line can.
be made to require no heavier gradient than 42 feet per mile. The
maximum gradient of 1 per cent, is only encountered in two
places, one four miles in length on the Atlantic side, and the
other descending to the Pacific, the length of the maximum gradi¬
ent on this side being twelve and a half miles. About two-thirds
of the entire length of the line the gradient will not exceed 26
feet per mile. Many varieties of valuable timber are found dura¬
ble in character and suitable for either permanent or temporary
work in construction throughout the entire route, with the excep¬
tion of about twenty miles at each end of it. There are no marsh
lands or questionable grounds encountered on the entire route,
and no important or difficult rivers to bridge—in short, the line
appears to present no engineering difficulties from a constructive
point of view.
With regard to the cost of the ship-railway complete, it is
stated that, from careful estimates based upon the surveys, the
entire project, including harbors, docks, roadway, and general
plant and machinery for transporting vessels of 5,000 tons gross
weight, will be about £15,000,000. As compared with that of a
canal this cost is very moderate, the estimated cost of the Panama
canal through a very much narrower point of the isthmus being
5
.¿T^i000'000- But the true comparison is that with a canal over
the same route, and the surveys and estimates for the ship-rail¬
way in Tehuantepec establish the fact that it can be built to carry
vessels of the same tonnage for a vastly less sum of money than
would be required for a canal there. As the track will be prac¬
tically straight, equal loads ought to be hauled upon it with less
expenditure of power or consumption of coal than on an ordinary
railway, and as there would be no handling by manual labor of
the cargoes transported, there would be no freight department
such as is required on ordinary railways, by which a very large
portion of the ratio of working expenses to total receipts would
be reduced below that of the most successful railways in opera¬
tion. Tonnage on first-class railways is transported at a profit
for one farthing per ton per mile, including the cost of repairs,
maintenance of way, motive power and all the expenses incident
to the operating of the road. It is believed that the ship-railway
transportation will be more economical than this, but at this rate
it would only amount to about 2s. iod. per ton for the tonnage
from ocean to ocean. It is believed by those who have investi¬
gated the subject that 35 to 40 per cent, of the gross earnings
will be sufficient to cover all the operating expenses of the line.
And here for the present we must leave the subject, only, how¬
ever, to return to the consideration of its constructive details in
our next.
NO. 11.
(" Ikon," September 19, 1884.)
In our previous notice of the Tehuantepec Ship Railway, pro¬
posed by Mr. James B. Eads, across the Mexican isthmus, we
considered the question from a general and historical point of
view, and described the route of the line. We now come to the
details of the mechanical means by which Mr. Eads proposes to
carry out a project which is remarkable alike for its boldness and
originality. It is also distinguished for its engineering soundness,
but these three attributes could hardly fail to be possessed by any
enterprise propounded by the man whose works on the Mississippi
have earned for him a lasting renown, in that they have raised the
port of New Orleans to a position second only to that of New
York. And it is in the details of the ship railway itself that
Mr. Eads's ingenuity as an engineer is especially manifested.
Nothing can exceed the perfectness with which every detail has
been worked out and every possible contingency provided against.
The proposed works mainly consist of a line of railway with pon¬
toon turntables on the way where it is necessary to divert the
traffic ; a dock at each end of the route ; pontoons for raising the
ships from water to land, and transferring them from land to
water ; and a travelling cradle for transporting ships of various
burthens across the country. The general construction and
operation of this ingenious plant and machinery can be seen from
6
a large working model which Mr. Eads has had made, and which
we recently had the opportunity of inspecting at 127, Long Acre,
London. Assuming a ship to have arrived at the port for over¬
land transport, she is elevated from the sea level to that of the
railway by means of a submergable pontoon. In practice this
pontoon would be about 450 feet long, 15 feet deep, and 75 feet
wide. It is arranged to float or sink in a basin, in which its verti¬
cal movement is guided, On each side of the basin there will be
twenty or thirty iron rods, arranged vertically, and secured to the
bottom of the basin. These rods will be capable of holding the
pontoon so as to prevent it rising above the level of the railway
when the ship and cradle have been taken from off it. The deck
of the pontoon is laid with three pairs of rails, which will corres¬
pond end to end exactly with those on the permanent land line
when the pontoon is floated. When in this position a cradle on
wheels, and capable of carrying the ship, is run on to the pontoon,
which is then submerged by admitting water into it through
sluice gates, which are regulated from the top of two quadrang¬
ular water-tight towers attached to the deck of the pontoon, and
between which there is sufficient width for the cradle and the ship
to pass. When the pontoon has been submerged to a sufficient
depth for the bottom of the ship to clear the supports upon which
it is intended she shall rest, the vessel is floated in from an
adjacent basin, and secured over the top of the carriage or
travelling cradle. The pontoon is then pumped out, and its deck
rises up to a given height above the water, its further progress
being stopped by the heads of the vertical rods before alluded to.
The rails on the deck of the pontoon now range precisely with
those on the land, and while the pontoon is in this position loco¬
motives are backed up and attached to the travelling cradle, and
it is started on its journey across the igthmus. On reaching the
end of the line the travelling cradle is run on to another pontoon,
which is submerged, and the ship floated off into another basin on
its way to its destination.
So far it will be seen that the principle of raising and lowering
the ship is broadly that adopted in the Victoria Docks, London,
and elsewhere. The detail practice, however, differs greatly, as
will presently appear, Mr. Eads having introduced many important
modifications in order to meet the more complex requirements
of the present case. For instance, in order to render the ship
railway practicable, it is absolutely necessary that the weight of
the vessel to be transported should be evenly distributed over the
wheels of the cradle, so as to limit the weight upon each wheel to
that ordinarily imposed upon the driving wheels of locomotives of
the present day. This is effected by placing in the deck of the
pontoon throughout its length and breadth a number of hydraulic
rams. One line of these rams extend through the centre of the
pontoon longitudinally, and these are designed to support the
7
keel at points 6 feet 9 inches apart throughout its whole length.
On each side of this centre line there is arranged another shorter
line of hydraulic rams which are intended to support the bottom
of the ship. On the outside of these lines are two other still
shorter lines for supporting the bottom nearer to the bilges, while
two other shorter lines outside these again support the bilges and
sides of the vessel. There are, therefore, across the middle port¬
ion of the pontoon no fewer than seven lines of rams, while a little
nearer to the bow and stern there are but five lines. Still nearer
to the bow and stern there are but three lines, and, finally the
the central line supporting the keel extends forward and aft of
these side lines nearly the entire length of the deck. These rams
are all connected together by a common system of pipes fitted
with valves, by means of which they may be separated into
certain groups. When the pontoon is sunk, and the weight of the
ship is on all these rams, if the entire system is connected togeth¬
er, it is evident that if there be more pressure on one ram than on
another this pressure will be equalized throughout the whole system.
Mr. Eads's idea is that the ship will not be curved,in the direction
of her length unless the roadway gives way under her. A first-
class roadway is therefore indispensable, and this having been
provided, no superior longitudinal strength is required in the
travelling cradle. But the weight has to be distributed over the
six rails which constitute the track, the two outer ones of which
are 29 feet apart. To do this it is necessary that the travelling
cradle shall be composed of strong traverse girders spaced 6 feet
9 inches apart from centre to centre. If we suppose a 3,000-ton
ship upon such a cradle having thirty transverse girders spaced as
above under the ship's bottom, the problem will be to cause each
one of these girders to carry 100 tons, or, in other words, to
transfer the excess of weight concentrated amidships to the ends
of the cradle, where the vessel is lean and lacks weight. This
problem is ingeniously solved by Mr. Eads in the following man¬
ner. When the travelling cradle is run on to the pontoon each of
the central girders comes exactly over seven of the rams, while
the end girders have only one ram under them, as the keel only is
to be carried by these girders. By making the one ram equal in
area to the aggregate area of the seven rams under each central
girder, it follows that the single large ram will, with the same
water pressure, lift as much as the seven together, and that if they
all have a common pressure the one large one will lift no more
and no less than the central seven. A few of the girders nearer
to the bow and stern have only five rams under them, and these
five have an aggregate area only equal to that of one of the large
rams. Where the ship becomes narrower there are only three
rams under each beam, the aggregate area of the three rams,
however, being precisely equal to that of one of the single rams
at the bow or stern, where only one support is available—namely,
8
under the keel. Now if all these rams, with their diameters thus
relatively adjusted, be forced up with a gentle pressure against the
ship while she is still floating, and the water valve admitting the
pressure be locked until she is lifted up by the pontoon out of the
water, it is evident that her weight will be evenly distributed right
away through from stem to stern—that is, every 6 feet 9 inches
each ram, and each series of rams, will hold 100 tons weight.
- Before quitting this part of the subject we would refer to an in¬
genious device which Mr. Eads has worked out for maintaining
the stability, or rather the equilibrium, of the pontoon when it is
under water during the process of either being submerged to
receive its load or rising to surface with it. This is a hydraulic
governor. As the pontoon has no connection with the surface of
the water after its deck is submerged, except by the two small
quadrangular towers already referred to, and which are placed
opposite each other at a point midway the length of the pontoon,
it is evident that the least unequal preponderance of weight in the
pontoon would cause the heavier end to sink and the lighter one
to rise. To equalise the flotation the hydraulic governors now
come in. These governors consist of four pairs of hydraulic cylin¬
ders, a pair being placed at each of the four corners of the
pontoon, one cylinder of each pair having its bottom end pointing
upwards and the other downwards, and each being secured to the
sides of the basin in which the pontoon works. The cylinders are
fitted with plungers which are connected with the corners of the
pontoon near the deck, so that when the pontoon descends one of
these plungers displaces a certain quantity of water from its cylin¬
der. At the same time the other plunger is withdrawn from its
cylinder, leaving in it a space exactly equal to the water driven
out by the first plunger. The water which is displaced out of one
of the cylinders at each corner of the pontoon when sinking is
driven by the descending plunger into the upper cylinder at the
opposite end and opposite side of the pontoon-—that is, at the
diagonal corner. If we suppose 100 tons more weight to be upon
one end of the pontoon than on the other, this weight would rest
upon the two descending plungers at that end, and would, of
course, be resisted by the water in their cylinders. In the
descent of these plungers this water is driven into the two upper
cylinders at the other end of the dock, where it forces the two
plungers out of those cylinders downwards on to that end of the
pontoon, and thus equalises or balances the extra weight at the
other end. The two ends and the two sides of the pontoon are
thus compelled to go down or to come up perfectly level.' To
prevent any torsion, and to insure the two diagonal corners of the
pontoon moving in exact accordance with the other two diagonal
corners, an extra pair of these governors would be used in prac¬
tice and would be fixed at one or other end of the pontoon and
placed in communication with each other across that end so that
9
they would compel the two corners at that end to go down simul¬
taneously, and through the other system the opposite ends of
the pontoon would also be compelled to obey the same motion.
When no disturbance of equilibrium occurred in the pontoon rising
and falling there would be no pressure in the pipes which connect
these hydraulic governors. It frequently happens, however, that
a vessel is much larger at one end than at the other, and while
she might be loaded on an even keel when afloat, the weight
would be very different when she was raised out of the water. In
lifting such a ship the pressure gauges upon the hydraulic governor
would at once indicate the excess of weight which one end or the
other of the cradle would have to sustain. If this were found to
be a matter of any moment, the dock would be lowered and the
ship moved forward or aft as the case might require, so as to dis¬
tribute the gross load more evenly over the cradle, the centre of
which coincides with the centre of the pontoon. If the weights
of the ship were evenly distributed forward and aft of her mid¬
ships they would inevitably be distributed equally over the
cradle, but if she were larger at one end than the other it would
be necessary to adjust her so as to prevent any undue preponder¬
ance of weight at either end of the cradle.
Having reached the point at which the weight of the ship is
evenly borne by the pontoon, we have next to consider how this
weight is to be transferred from the pontoon to the cradle before
the latter is run on to the railway, and thus to obviate the neces¬
sity of carrying the hydraulic rams across the country under the
vessel. This is effected by another simple but ingenious arrange¬
ment. The heads of the rams do not come in direct contact either
with the girders or the ship, but over every ram is a vertical screw
jack, which passes up through the girder, and when pressure is
applied by the ram, the head of the jack is pushed up against the
bottom of the ship. Each of the largest-sized cradles will, there¬
fore, be supplied with a number of screw jacks equal to the whole
number of rams in the pontoon, the smaller cradles having a lesser
number ; and when any cradle is run on to the pontoon, it is
stopped and secured by a very simple locking arrangement, so that
each one of the screws comes directly over a ram. The screw jack
resembles an prchestral music stand, having a flat head, formed of
steel plate, and which in practice would be about 3 feet square.
This head-plate is secured on the top of the screw by means of a
toggle joint, which enables the plate to adjust itself to any angle
presented by the ship's side. In order to prevent damage to the
ship from abrasion, the top of the plate is cushioned with rubber,
so that it perfectly adjusts itself to the curvature and surface in¬
equalities of the vessel. The stem of each of these screw jacks is
provided with an adjusting nut, which is run up against the upper
end of the screw near the plate, and when the rams are down,
these nuts stop the descent of the jack by their contact with the
10
top side of the girder on which they will rest. When the ship is
floated in over the cradle, the heads of the screw jacks, with the
nut beneath each, are all down resting on the platform of the
cradle, with their stems hanging below in the ^ater directly over
the rams. A small amount of water pressure put upon the rams
raises these screw jacks with their head-plates pressed up against
the bottom of the ship and throughout the entire length of her
keel. This having been done, the valve admitting water to the
rams is closed, so that the water cannot escape, and the pontoon
is then pumped dry and the ship raised out of the water, supported
on the screw jacks, which in their turn are supported by the hy¬
draulic system in the deck of the pontoon. In this position the
nuts will be found to be at varying heights above the tops of the
girders. The nuts are, therefore, screwed down with their under
sides resting on the girders, which in effect constitute the platform
of the cradle. The valves of the rams are now opened, and the
pressure being relieved the rams retire downwards, and the
weight of the ship is evenly and without alteration transferred on
to the platform of the cradle.
It will thus be seen that the adjustment of the cradle to the
ship is absolutely perfect, and that the weight of the vessel is
thus properly and evenly distributed, so that she cannot possibly
take harm when she ceases to be waterborne, or in other words
when she is carried by the cradle. This latter has a broad base,
and is mounted on about 360 wheels, each wheel being flanged on
both sides. Each of the platform girders is supported by twelve
strong spiral springs resting on the bearings of twelve of these
wheels, and as each girder carries but 100 tons of the dead load, each
spring transfers to a wheel 8yí tons. Each spring requires 20
tons to close it, and has a range of 5 inches. When the rams are
withdrawn the weight of the platform rests on these springs, and,
of course, partially closes them, leaving still 2% inches or 3 inches
of play in each spring to allow the wheels to pass over any in¬
equality of the rails which may happen to exist. The wheels are
hung independently—that is, each is separate from its fellows,
having its axle protruding on each side sufficiently far to furnish
a proper bearing. The breakage of any one wheel, therefore,
would not affect any other wheel ; and if even a dozen were to
break, the great number that would be left would possess such an
enormous surplus of strength, compared with the broken ones,
that derailment may be considered as practically impossible. The
chances of derailment are still further reduced by the circumstance
that the railway will have no curves, and the speed will be limited
to ten miles an hour. Mr. Eads considers that besides the equal
distribution of the load over the wheels, the avoidance of all
curves in the road is absolutely necessary to render ship railway
transportation practicable. By this means the-wheels can be
placed much closer together, besides rendering unnecessary the
11
use of bogie trucks or other complications. It is not, however, to
be supposed that because the curves are avoided the route follows
one straight undeviating course from shore to shore. On the con¬
trary, there are several deviations from a direct line, and the way
in which these deviations are provided for forms another interest¬
ing element of the project. In order to avoid having curves, and
at the same time the necessity of making enormous excavations
to preserve the straight direction of the road, Mr. Eads introduces
floating turntables wherever it is necessary to change the direc¬
tion of the route. This ingenious device not only serves this pur¬
pose, but it constitutes a shunting place, where ship carriages
coming from opposite directions may conveniently and rapidly
pass each other. This floating turntable consists of a large rectan¬
gular pontoon, which in practice would be about 450 feet long by
70 feet wide and 12 feet deep. This pontoon is placed in a seg¬
mental basin, in which it is secured by a central pivoted joint.
The segments of the basin are made sufficiently large for the
pontoon to rotate around several degrees of a circle, according to
the amount of deviation the direction of the road may require to
avoid heavy cuttings. The central joint on which the pontoon
is secured is hollow, and through it the water in Jhe pontoon is
extracted by means of a large pump. Sluice gates in the side of
the pontoon allow the water in the basin to flow into the pontoon
when it is necessary to destroy its buoyancy, in which condition
it rests upon segmental bearers on the bottom of the basin. The
top of the pontoon is laid with rails, which coincide with those
on the main line, and it thus constitutes a swing bridge, and at
the same time forms a part of the permanent way. When the
travelling cradle with the ship on it has been run on to the pon¬
toon the water is pumped out of it through the central joint, and
and is discharged into the basin until the pontoon is on the eve of
floating. The pontoon is divided up into compartments by bulk¬
heads, so that the water can be drawn from either end or either
side as may be necessary to ensure its being emptied evenly. In
this condition it is easily moved around like an ordinary railway
turntable, but it is not necessary that it shall rise from its bearing
in order that it may be revolved. By means of a small engine
placed on each end of the pontoon to wind a cable made fast to
the sides of the basin, the pontoon with its freight is turned round
until its rails coincide with those on one of a series of radial
sidings which corresponds with the altered direction of the route.
When turned to the desired position, the sluice gates in the pon¬
toon are raised and the water flows back from the basin into the
compartments, thus preventing the pontoon rising when the load
is taken off its deck. Where streams exist on the line or route
pumping engines will not be necessary to operate the floating
turntables, as the water of such streams would be stored in the
reservoirs and used for this operation when needed. The water
12
taken out of the pontoon would be run to waste through the cen¬
tral joint into a sluice. Such are the arrangements of Mr. Eads's
proposed ship railway, which evince the most careful attention to
details, and demonstrate that he has provided against every con¬
tingency, and has practically ensured the safe transport of ship
and cargo overland. We have yet to show the feasibility and the
practicability of the project from an engineering point of view,
and to enter into the commercial considerations affecting the
question, which matters we reserve for a third and concluding
article.
NO. III.
( " Iron," October 'Sd, 1884.)
The questions pertaining to the route, the works, and the plant
and machinery of the proposed ship railway across the Mexican
isthmus having been dealt with in our two previous articles, we
now come to those considerations which bear upon the feasibility
and the practicability of the project, and likewise to those of a
commercial character. But before touching upon these points we
have a few further observations to make upon some of the con¬
structive details. It will be remembered that the weight of the
ship will be distributed evenly over the transporting cradle by
means of screw jacks operated in the first instance by the hy¬
draulic rams of the pontoon. In addition to what we have already
stated, we may here observe in this connection that the wheels
and axles of the travelling cradle will be tested to carry 20 tons
each, and the rails will be of ample section and strength—about
120 lb. to the yard—to prevent injury from the weight of the
passing load, even though thrice that weight were brought on
them. But the method of distributing the weight equally through¬
out the length of the cradle is believed to be so perfect that in
ordinary practice and rapid handling of ships the wheels at
one end of the car would rarely carry more than half a ton in
excess of those at the other end. The hydraulic governors would
enable the superintendent to know exactly how much more
weight there was at one end of the cradle than at the other. Mr.
Eads proposes to vary the sizes of the traveling cradles in order
to suit the different sized vessels. The largest cradles would be
designed to carry a ship weighing 5,000 tons. As it is intended
to construct the line for profit, the works would not be of sufficient¬
ly large proportions either in the docks, cradles, or railway, to
carry the Great Eastern, although, if in the future the transport
of such large vessels should be required and promise to be profit¬
able, it would be practicable to carry them by increasing the
width of the road bed, the size of the cradles, and the flotation
power of the pontoons and turntables. Ships of 5,000 tons gross
weight will include 90 per cent, of the present tonnage of the
world, and the ship railway will be constructed to accommodate.
13
those as the maximum sized vessels. The single track (of three
pairs of rails) is considered to be capable, with only the five turn¬
tables that are necessary to change the direction of the road in
difficult parts of the line, to permit of ten or twelve ships start¬
ing from each end of the line to pass each other -daily, and to
accomplish the trip in from fifteen to eighteen hours without any
difficulty. If these vessels average 1,500 tons each day they
would amount to at least one quarter more than the Suez Canal
is accommodating to-day. Moreover, there is nothing to prevent
a double track being laid should the traffic justify it, and this
without interruption to the regular business of the line.
The question of endangering the structural integrity of a ship
loaded with cargo by taking her out of the water and placing her
on intermediate supports is one which has frequently been raised
only to be summarily disposed of by those who give the matter a
moment's thought. As, however, there is still a popular notion
that a loaded vessel under such conditions is subject to injurious
strains, it may be as well if we point out how utterly impossible
this is by reason of the construction of the vessel itself. No
greater fallacy than this was ever conceived, for there is no form
of structure which is known to be subject to more unequal, irregu¬
lar, and ever-varying strains than a ship at sea, and these very
points are carefully provided against in her design and construc¬
tion. A properly designed and constructed ship resembles a
girder, and is so built that no matter how she maybe tossed about
on the waves, the strains, conflicting and almost puzzling as they
are, are distributed equally through her framing and plating or
planking. If there was any fear of her cargo bursting her sides,
as some have held there is, it would have burst them on her first
loading, as although water is incompressible in confinement, it is
exceedingly yielding when unconfined. Hence, the risk of dam¬
age to vessels by straining during transport overland, may at once
be set aside as puerile, especially in the face of the ingenious ar¬
rangements designed by Mr. Eads for equalising their support.
Moreover, the raising of ships, with their cargoes, from a lower to
a higher level, by means of hydraulic lifts, has been successfully
accomplished for long past. The Victoria Docks, in London, and
those at Malta and Bombay, have been opera.ted for years without
an accident. Again, it is a matter of common occurrence to keep
loaded vessels for days, and even weeks, upon dry docks for re¬
pairs, and then return them to the water without the slightest
strain or injury. Small steamers, moreover, are now being trans¬
ported by rail from one lake to another in Prussia, with as much
safety on the rail as in the water. More than forty years ago the
boats on the Pennsylvania Canal were drawn upon a railway, up
some of the steeper inclines of the route over the Alleghany
Mountains, without injury, and, going back to history, we find
that the Greeks transported their war ships across the Isthmus of
14
Corinth 400 years before the Christian era. It is now proposed to
transport larger vessels, and the whole question is simply one of
the distribution of weight over an extended area of ground by the
use of a number of rails and many wheels, together with the em¬
ployment of sufficient motive power in the way of locomotives.
With regard to the practicability of the scheme as a whole,
there is the undoubted evidence of some of the ablest engineers
and ship constructors in this country and America in its favor.
During the time the Committee on Commerce of the United States
Senate was investigating the merits of the scheme, they took,
among other evidence, that of Sir E. J. Reed, K.C.B., M.P., who
testified in detail and at considerable length to the practicability
of Mr. Eads's project. Besides Sir Edward Reed, Mr. Nathaniel
Barnaby, C.B., Mr. William John, formerly of Lloyd's, but now
of the Barrow Shipbuilding Company, Mr. John Fowler, C.E., Mr.
G. F. Lyster, C.E., and Mr. Leader Williams, C.E., transmitted
similar opinions to the committee, which finally reported that the
testimony they had obtained conclusively demonstrated the fact
that such a railway was entirely practicable, and that loaded ves¬
sels could be transported over it with absolute safety and economy.
Professor Elgar, Mr. B. Baker, C.E., and Mr. Martell, of Lloyd's,
have, moreover, added their testimony in its favour. In fact, it is
obvious that any question of safety in transport can only be raised
by those who are either unacquainted with, or unmindful of, the
strains that ships undergo at sea.
We have seen that Mr. Eads has a valuable concession ; that
Tehuantepec possesses peculiar advantages over any other route,
and that a ship railway across the Mexican isthmus is quite prac¬
ticable. It now only remains for us to consider whether, if the
railway were made, it would prove a financial success, or, in other
words, whether there would be sufficient business to make it pay.
To answer these questions we must refer to some official docu¬
ments, issued by the United States government. In 1879 Mr.
Nimmo, chief of the Bureau of Statistics, made an official report,
in which, among other things, he submitted the following table,
which is based upon statistics of the latest year for which the re¬
quisite data can be obtained".—
Number of Vessels and Amount of Tonnage which might have passed throvgh the
proposed Panama Canal if it had been constructed.
Number of Tons.
Vessels.
1. Average number of vessels and amount of tonnage entered
at and cleared from either side of the Isthmus of Panama,
annually, in trade with all nations .... .... 338 533,000
2. Vessels entered at and cleared from Pacific ports of the United
States in trade around Cape Horn, with the Atlantic ports
of the United States, during the year ended June 30, 1879 75 120,662
3. Vessels entered at and cleared, from Atlantic ports of the
United States in trade with foreign countries west of Cape
Horn, during the year ended June 30,1819 .... 273 247,567
15
4. Vessels entered at and cleared from Pacific ports of the
United States in trade with foreign countries east of Cape
Horn, during the year ended June 30, 1879 .... .. 455 551,929
5. Vessels entered at and cleared from ports of the several
countries of Europe in trade around Cape Horn, with
foreign countries other than the United States, during the
latest vear for which the data can be stated with respect to
each country .... — 1,644 1,462,897
6. Vessels entered at and cleared from ports of British Columbia
in trade with countries of Europe during the year ended
June 30, 1879 .... ... ... .... 33 22,331
Total 2,818 2,938,386
Since the date when the above table was made (1879), owing to
the enormously increased grain production of the Pacific coast re¬
gion, the tonnage has become very much greater. Mr. Nimmo
placed the total grain for shipment, in his estimate, at 550,000
tons, whereas, according to official figures furnished by the de¬
partment of agriculture of the United States, it appears that the
total wheat crop of California in the year 1879 amounted to 29,-
017,707 bushels, while in 1882 the crop amounted to 36,046,600
bushels. These figures show an increase in the crop in three
years of 7,028,893 bushels, or about 8 per cent, per annum. The
total wheat produced in 1882 by California, Oregon, and Washing¬
ton territory was 50,525,900 bushels. A deduction of 30 per
cent, from this amount for bread and seed, viz. 15,157,770 bushels,
leaves the aggregate surplus crop of 35,368,130 bushels for 1882
according to the Bureau of Agriculture. Assuming that the ship
railway, if carried out, will be completed in 1888, and that the in¬
crease of the production of wheat observes the same ratio, there
will then be 1,416,304 tons of wheat alone for export from these
three American states.
Deducting the 550,000 tons included in Mr. Nimmo's report from
his total estimate of 2,938,386 tons, and adding to the remain¬
der the above amount of wheat based on the Bureau of Agricul¬
ture, we have 2,388,386 + 1,416,304 = 3,804,690 tons. This, how¬
ever, only includes the estimate of Mr. Nimmo for the tonnage of
1879 from all other sources, namely, 2,388,386 tons. It is reason¬
able to believe that this tonnage has increased at the rate of 5
per cent, per annum, and that in 1888 it will, at that ratio, amount
to 3,463,159. This, added to the wheat export of the three'
United States Pacific States, will give a grand total of 4,879,463
tons. This is probably under the actual amount of tonnage that
would await the opening of the ship railway in 1888, for the wheat
shipments from British Columbia have kept pace with the increase
in California, Oregon, and Washington territory ; while the export
of fish is assuming very large proportions, 25,000 tons of canned
salmon having been shipped in one season recently from Portland
alone. The shipments of lumber from Puget's Sound and the
Pacific States would doubtless be enormous when those countries
are brought 8,250 miles nearer by sea to the great marts of the
Atlantic than they now are. We may, therefore, reasonably as-
16
sume that the tonnage which would cross the ship railway in 1888
would not be less than 5,000,000 tons. These 5,000,000 tons could
well afford, to pay 16s. per ton, which would give £4,000,000 as
gross receipts. It is estimated that less than 50 per cent, of this
would pay all working expenses, thus leaving £2,000,000 as net
profit, or 5 per cent, on ¿£40,000,000, whilst £"15,000,000 is stated
to be an extremely liberal estimate for the cost of the whole line.
In fact, it is believed that, with economy, £12,000,000 would cover
the cost of construction.
Turning from commercial considerations and looking at the
Atlantic and Pacific Ship Railway from a broad and general point
of view, we can but regard the project as one which is fraught
with very great results. This will be readily seen when we con¬
sider that the American isthmus separates about 100,000,000 of
the most enterprising, industrious and enlightened people on the
earth, inhabiting the North Atlantic coasts of Europe and Amer¬
ica, from 600,000,000 souls who inhabit the Orient and islands of
the Pacific. It is true that the sailing distances which separate
England from India, China, and other Oriental nations have been
greatly lessened by the Suez Canal, but these distances are almost
insignificant when compared with those which the ship railway
would annihilate. For instance, the greatest saving effected by the
Suez Canal between London and Calcutta is about 4,500 statute
miles ; whereas the sailing distance by the ship railway from Lon¬
don to every port on the Pacific coast of North America would be
lessened by nearly twice this vast distance, or about 8,250 miles.
The Suez Canal brought London and Canton about 3,500 miles
nearer together by sea. The ship railway would save more than
three times this distance between the great American metropolis
and every port in British Columbia. The American isthmus and
the cordilleras of North America constitute a narrow but almost
impassable barrier to the interchange of the manufactures and pro¬
ductions of forty millions of people in the Mississippi Valley and
Atlantic States, not only with those of ten millions of their coun¬
trymen to the west of them, but with the products of nearly a
hundred million others on the islands and coasts of the Pacific,
who are seemingly their nearest neighbours. The ship railway
would give to these descendants of the British Isles a sea route:
between their Atlantic and Pacific ports scarcely a thousand miles
longer than the railway between New York and San Francisco,
and it would give to the vast valley of the Mississippi a gateway
equivalent to the discharge of its mighty river directly into the
Pacific. A work designed to effect such enormous benefits to
the commerce of the world should commend itself with especial
force to this country, which to-day is carrying more than 70 per
cent, of that commerce. We cannot but wish this unique project
every success, and would in conclusion quote a couplet from
Wordsworth's " Highland Broach," which, taken alone and read
by the light of Mr. Eads' scheme, reads like prophecy :—
" Lo ! ships, from seas by nature barred,
Mount along ways by man prepared."