IMPROVEMENTS IN THE CONSTRUCTION OF ATMOSPHERIC RAILWAYS AND CARRIAGES, AND IN WORKING THE SAME
Year: 1865

page_text: PROVISIONAL SPECIFICATION left by Alexander Doull at the Office
of the Commissioners of Patents, with his Petition, on the 1st August
1865.
I, ALEXANDER DOULL, of Westminster, Civil Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF
ATMOSPHERIC RAILWAYS AND CARRIAGES, AND IN WORKING THE SAME," to be as
follows:-
The first part of my Invention relates to the employment of atmospheric
pressure in propelling trains upon portions of locomotive lines where there
exist steep inclines The atmospheric tunnel or tube is formed of any suitable
material and of any convenient size so as to pass the passenger carnages and
luggage vans but not the locomotive engine. The permanent way is the
same as on the locomotive lines with which the incline is connected, and the
tube when above ground or partly above ground may be constructed in
manner hereafter described.
A diaphragm carriage is placed one in front and one in rear of the train;
The
these carriages are generally constructed on four wheels with breaks
haphragms attached to these carriages are constructed so that the base fills
the tube of whatever shape it may be made, leaving a space of about one inch
all round. The outline of the diaphragm is generated by a semi-revolution
of one balf of the figure formed by a cross section of the tube upon its vertical
Jais slightly modified when the base is a straight hue or nearly so. The space
sound the diaphragm is filled up by a fringe of any soft or elastic substance, and

page_text: being attached to the middle of the diaphragm, lies against the side of the tube
at a very oblique angle. The air is withdrawn from the tube in front of the
train and compressed into the tube behind the train in ascending an incline,
but in descending the process is reversed; the air is withdrawn from the rear
of the train and compressed in fiont in order that the train may descend
safely and at any required speed. The concave side of the diaphragm is
placed towards the compressing engine so as to receive the compressed air into
the concavity of the diaphragm and the convex side towards the rarefying
engine. The diaphragms are reversed upon the extremities of their vertical
axis, and are so constructed that portions may be opened or folded up in order
to throw off the propelling power.
Another improvement consists in the construction of a continuous carriage
or rather carriage body without wheels or axles; this continuous carriage is
built in short lengths depending upon the radius of the curves to be passed
round. The principal part of the structure consists of two longitudinal pieces
of framing which may be composed of wood or iron of the T or any other
form, framed parallel and about three feet apart, the cross framing supporting
the flooring of the carriages; I provide a passage along the centre of the
carriage with seats on each side of the passage.
The several portions of the carriage are rigidly attached to each other at a
central point by a universal joint, and the longitudinal pieces of framing are
continuous, as they have to pass over sets of friction rollers placed about five
feet apait longitudinally and also flexible in order to pass round curves; these
two objects are attained by articulating the ends of the pieces of framing
into each other, the articulations radiating from the centre where the universal
joint is placed; these articulations draw out on one side and are pushed in on
the other side according to the direction of curvature, and they are sufficiently
long to preserve the continuity of bearing surface on the friction rollers. The
whole train would virtually be one carriage with a passage along the centre
from one end to the other; still it would be temporarily divided into the
usual number of classes, with separate entrances to each class.
The carriage is constructed of the lightest material consistent with the
necessary strength, the carriage may, however, consist simply of a strong
fiamework, with high-backed sofas on each side of the longitudinal passage,
or the circular or other shaped top may be continued all round by very light
material. The doors are made to slide into or along the framing of the
cariage.
The tube or tunnel may be of any shape or size, but I prefer a cucle of
about seven feet diameter, it may also be formed of any available and suitable

page_text: material, such as stone, ashlar, or rubble, and it the latter it should be
smoothly plastered inside. I prefer, however, a cast-iron invert imbedded in
concrete cast in five-feet lengths; the several castings are well joggled and
bolted together. On each casting there are two projections, one on each side
about three feet apart, horizontally formed, for the reception of friction rollers,
upon which the train is propelled by atmospheric pressure; there are also
projections joining these projections longitudinally in order to form a con-
tinuous and symmetrical projection for the guide wheels connected with the
train and diaphragm carriages to run against, and also for the breaks
attached to the latter to act against. In connection with this cast-iron invert,
the other portion of the tunnel may be constructed of stone, brick, or any other
suitable material. In passing under rivers or estuaries the tunnel may be most
advantageously completed in cast iron put together in segments which I construct
in the following manner:-Let A, B, C, in the annexed Diagram represent a
tunnel or tube seven feet in diameter constructed under the bed of a river or
estuary. The work being accurately set out and the cast invert adopted,
as already described, and the remainder of the tube would also be completed
by strong castings put together in convenient segments with the flanges bolted
together inside as being the most convenient in this mode of construction;
this would necessitate the subsequent adoption of a thin smooth lining of wood
or metal being applied to the inside of the tube with the exception of the
invert; the joints would be made air and water tight in the usual way. The
work being carried on as far as D, or until water got into the works, air-
tight valves would then be placed at D and E, and air would be forced into
the portion of the tube from the valve E to the end of the heading, the density
of which would depend upon the head of water which had to be contended
against. The distance from the valve E to the valve D would be employed
as an air lock, and may be of any convenient length according to the magnitude
of the works. When it is necessary to send men and materials into the
work the air is allowed to escape from the air lock D, E; the valve E would
then open and the valve D remain shut. A quantity of materials and tho
required number of men would then be introduced into the air lock D, E,
the valve E shut and air admitted into the lock from the portion of the
tube from D to the face of the work, and when an equilibrium is established
the valve D would open and the materials would be taken to the works. Tho
excavated materials could be most easily disposed of by laying down temporary
rails on a gauge of about two feet six inches, and adopting small waggons,
several of which loaded could be diawn into the air lock, the valve D shut,
the air allowed to escape from the lock, when the valve L would open and the

page_text: waggons be drawn out. The materials could now be sent in by the return
waggons, and the process continued in this way at each end of the tube until
complete. The work of excavation would proceed in the usual manner in
which such works are conducted, which must vary with circumstances and
with the nature of the strata; but by keeping a sufficient depth under the
bed of the river, and considering the small diameter of the tube, no great
difficulty nor delay need be anticipated. The invert may also be composed of a
timber framing, upon which suitable castings are bolted down for the purpose
of receiving the friction rollers and guide pieces above referred to.
Another improvement is in the construction of the atmospheric tunnel or
tube where it is partly or altogether above ground; it is composed of malleable
iron ribs rolled into an H shape and of sufficient strength. Thoso rolled bars
are bent to the required shape, placed at a distance of about three feet apart
with occasional cross ties, and the spaces between filled in by wood, slate,
glass, flag, earthenware, or other suitable material, and when completed
asphalted or tarred over and covered with brown paper or other material to
make it air-tight. This mode of construction is peculiarly applicable in
changing an underground railway to my system, whether in a tunnel or- deep
open cutting. When these tubes would pass through a tunnel the spaces
between them and the top of the tunnel would be available, and I propose to
employ it as reservoirs for compressed or rarefied air for the economical pro-
pulsion of the train.
The improvements in stations intermediate and terminal consist in con-
tinuing the tube or tunnel of the same form at the station as at any other
portion of its length by a framing or casing partly consisting of fixed
portions and partly of doors which open on the platform, and when, as at
intermediate stations, the train is not intended to stop, the tube remains
entire and the train passes along. At terminal stations when the train stops
the opening portions of the tube are removed, and the passengers step out of
the carriages on to the platform. The valves connected with the tube are
opened and shut by hand or by the motion of the train, and I derive the motive
power from a fan-blower or from a powerful air pump in the manner well
known and in general use.