IMPROVEMENTS IN CONSTRUCTING ATMOSPHERIC RAIL- WAYS AND CARRIAGES, AND IN WORKING THE SAME, PARTS OF WHICH ARE APPLICABLE TO EXHAUSTING AND, CONDENSING AIR FOR OTHER PURPOSES
Year: 1865

page_text: LETTERS PATENT to Alexander Doull, of Westminster, Civil Engineer
for the Invention of "IMPROVEMENTS IN CONSTRUCTING ATMOSPHERIC RAIL-
WAYS AND CARRIAGES, AND IN WORKING THE SAME, PARTS OF WHICH ARE
APPLICABLE TO EXHAUSTING AND, CONDENSING AIR FOR OTHER PURPOSES."
Sealed the 5th June 1866, and dated the 9th December 1865.
PROVISIONAL SPECIFICATION left by the said Alexander Doull at the
Office of the Commissioners of Patents, with his Petition, on the 9th
December 1865.
I, ALEXANDER DOULL, of Westminster, Civil Engineer, do hereby declare
the nature of the said Invention for "IMPROVEMENTS IN CNSTRUCTING ATMO-
SPHERIC RAILWAYS AND CARRIAGES, AND IN WORKING THE SAME, PARTS OF WHICH
ARE APPLICABLE TO EXHAUSTING AND CONDENSING AIR FOR OTHER PURPOSES," to be
as follows:-
any
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 suitable
material, and of any convenient size, so as to allow the passenger carriages
and luggage vans to pass through, but not the locomotive engine. The
permanent way is of the same description as that on the locomotive line with
which the incline is connected. The atmospheric tube when intended for a
purely atmospheric line, and when it is above ground or partly above ground,
or when under the bed of a riveror an estuary may be constructed as hereafter
explained. A diaphragm carriage is placed one in the front, and one in the
rear of the train, or in any other convenient position. These carriages

page_text: are generally constructed upon four wheels with breaks. The diaphragms
attached to these carriages are formed so that the base would fill the tube or
tunnel of whatever shape it may be made, leaving a space of about one in ch
all round. The outline of the diaphragm is generated by a semi-revolution of
one-half of the figure formed by a cross section of the tube upon its vertical
axis, slightly modified when the base of the tunnel is a straight line or nearly
so. I do not, however, confine myself to this particular form. The space
around the diaphragm is filled up by a fringe of any soft or elastic substance,
and being attached to the inside of the diaphragm lies against the inside of
the tube at a very oblique angle. The diaphragms are composed of thin
metallicorothersubstance, and strengthened by ribs,and they are constructed
so that portions of them will open or fold up in order to throw off the propelling
power when necessary. When however an incline on each side of a mountain
range is very steep, one in ten or even still higher, I intend to work over the
summit in the following manner:-I constructian atinospheric tube or tunnel
over the summit of a mountain range. In the tube at the bottom of each
side of the mountain I place a valve or folding air-tight doors forming an
angle pointing outwards. Near the summit of the tube I place two engines,
one for each half of the tube, and each provided with an apparatus for with-
drawing the air from the portion of the tube on one side of the mountain, and
also from an accumulator at the summit of the mountain. This accumulator
is an air-tight space formed ofany shape,so that the greatest amount of internal
capacity can be obtained with the least expenditure of labour. I take advantage
of any natural cavern which may exist at or near the summit of the mountain
and line it so as to make it air-tight. When it is necessary to start a train
from the bottom to the top of the tube a diaphragm carriage is placed in the
tube as near to the valve as may be convenient, and the air contained in the
small space between the diaphragm carriage and the valve is allowed to escape
into the vacuum in that portion of the tube by opening an aperture in the
valve. The pressure being thus equilibrated on each side of the valve, it is
easily opened, and the train attached to the diaphragm carriage will proceed
up the incline at a velocity proportioned to the extent of the vacuum and to
the other circumstances of the case. If the vacuum was very high the speed
would bevery rapid for some considerable distance, until the air by the progress
of the train became condensed faster than the engine could extract it. The
air is then allowed to rush into the accumulator from the tube, which greatly
assists the engine and accelerates the progress of the train to the summit.
A diaphragm carriage is also placed behind the train to prevent the possibility
of an accident should the coupling chains of the carriages give way in ascend-

page_text: ing the incline. The connection of the tube with the engine and with the
accumulator is placed at a sufficient distance back from the summit valve
to allow space for the condensation by the diaphragm of a cushion of air to
assist, in addition to the breaks, in stopping the train at the summit when
necessary. There are two valves placed in the tube at the summit pointing
outwards, or one valve constructed to resist pressure in both directions.
When the descending train passes into the portion of the tube on the opposite
side of the mountain a valve is shut behind it, so that the train will form a vac-
uum or partial vacuum behind it. The progress will therefore be very slow, the
air in the accumulator, which may be considered at the density of the atmo-
sphere, is then permitted to rush into the vacuum, not in large quantities
but just sufficient to allow the descending train to move at a safe speed.
When the supply of air from the accumulator to the rear diaphragm of the
descending train is exhausted, and a partial vacuum thus formed in the
accumulator,it is shut in order to preserve this vacuum,and air is then admitted
from the front of the train to the rear through valves in the diaphragms, and
the quantity of air which is thus allowed to pass from the plenum in front of
the train to the partial vacuum behind it governs the speed of the train.
But in order to guard against the possibility of an accident to the train in
its descent, the valve at the bottom of the tube is kept closed, and is opened
only by the motion of the train when it approaches sufficiently near for that
purpose. Should the valve behind the descending train be left open through
any cause, and the pressure be equal in front and behind the train, the
progress of the train will soon condense the air in front so as to regulate
the descent or altogether stop the speed of the train. When the accumulator
has been shut after the descent of a train, the engine on that side of the
summit which the train had previously ascended is caused to commence to
exhaust the air from the accumulator, and the other engine commences to
extract the air from its portion of the tube so soon as the train has passed
through the valve at the bottom preparatory to the ascent of the next train
from the opposite direction. Should the traffic on a line of the above descrip-
tion be very considerable there will be no difficulty in arranging a passing place
at the summit of the mountain range. In a country where there is an elevated
mineral district with a heavy traffic descending, and little more than empty
trucks ascending,the traffic could be worked very economically,as the partial
vacuum left in the tunnel by a descending heavy train would take up a light
train with some assistance from an engine and an accumulator at the summit.
Another part of my Invention relates to the construction of a continuous
carri ige, or rather carriage body, without wheels or axles. This continuous

page_text: carriage is constructed in short joints or lengths, depending upon the radius
of the curves to be passed round. The principal parts of the structure
consist of two longitudinal pieces of framing, which may be composed of
wood or iron of the T-form, or of any other suitable form or dimensions
framed parallel and about three feet apart, the cross framing supporting the
flooring of the carriage. There is 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 should be continuous, as they have to pass
over parallel sets of friction rollers placed about 5 feet apart longitudinally;
they should also be 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 are formed by alternate tongues and recesses on each of two
adjoining pieces of framing which take into each other; they draw out on one
side and are pushed in on the other side according to the direction of curva-
ture, and they are sufficiently long to preserve the continuity of the bearing
surface on the friction rollers. When the line is straight the frame forms a con-
tinuity of hearing surface for the purpose of passing over the friction rollers;
in passing round a curve, either to the right or to the left, the tongues pass in
opposite directions into or out of their corresponding recesses; in order to
prevent the tongues from passing each other vertically in consequence of any
pressure to which they may be exposed in that direction they are tongued and
grooved into each other, but free to move laterally and to some extent verti-
cally. The extent of lateral motion which it is necessary to provide for in any
particular case is determined by the radius of the sharpest curve on the line,
and in passing round very sharp curves these flexible joints should occur
more frequently. The portion of the floor of the carriage from the centre
outwards, which would be open by the arrangement just described is covered
over by an overlapping board fixed at one side only, or by vulcanized
indian-rubber. The whole train is virtually one continuous carriage with a
passage along the centre from one end to the other, except that it is divided
into the usual number of classes with separate entrances to each.
The carriages are constructed of the lightest material consistently with
the necessary strength. They may, however, consist of a strong frame-
work with high-backed sofas on each side of the longitudinal passage. The
doors are made to slide into or along the side of the framing of the carriage.
One entrance may, however, be sufficient at the end of each class of
carriages, in which case doors may be altogether dispensed with.

page_text: The tube or tunnel when intended for a purely atmospheric line may
be of any shape or size, but 1 prefer a circle of about 7 or 8 feet in
diameter. It may also be formed of any available or suitable material, such
as brick, stone, ashlar, or rubble, and if the latter, be smoothly plastered
inside. I prefer, however, a cast-iron invert imbedded in concrete cast in
5 feet lengths, the several castings to be well joggled and bolted together.
On each casting there are two projections, one on each side about 3 feet
apart, horizontally formed for the reception of friction rollers, upon which the
train is propelled by atmospheric pressure. There are also longitudinal pro-
jections between these projections to form a continuous 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
agaiust. In connection with this cast-iron invert the other portions of the
tunnel may be constructed of stone, brick, or any suitable material. In
passing under rivers or estuaries the tunuel may be most advantageously
completed in cast iron, put together in segments as hereafter described.
The invert may also be composed of a timber framing, upon which suit-
able castings are bolted down for the purpose of receiving the friction
rollers and guide pieces above referred to.
Another improvement relates to the construction of the atmospheric tubeor
tunnel when it is partly or altogether above ground. It is composed of
malleable iron ribs rolled into an H shape, and of sufficient strength to resist
internal and external pressure. These rolled bars are bent to the required
shape, placed about 3 feet apart with occasional cross ties, and the spaces
between filled in with wood, slate, flag, glass, earthenware, or any suitable
material, and when completed the whole is asphalted or tarred over and
covered with brown paper or other material, so as to render the tunnel air-
tight. When the filling is composed of glass it may be desirable to leave
the glass exposed, so as to obtain light in the tunnel.
This mode of construction is peculiarly applicable in changing an under-
ground railway, whether in a tunnel or in a deep open cutting, into two or
three atmospheric tubes. When these tubes pass through a tunnel the
space between them and the top of the tunnel is available, and I employ it
as a reservoir for rarefied air to be employed in the economical working of
the trains.
. I construct an atmospheric tunnel or tube under a river or estuary in the
following manner:-The work being accurately set outand the cast-iron invert
adopted as already described, the tube is completed by strong castings put
together in convenient segments with the flanges bolted together inside. This

page_text: mode of construction necessitates the subsequent adoption of a thin smooth
lining of wood or metal applied to the inside of the tube with the exception of
the invert. The joints are made air and water tight in the usual way. I
adopt the following mode of securing the several segments of the cast-iron tube
together The tube being, say, 7 or eight feet in diameter, is divided
into four or six segments, one invert of 4 feet, and an upper or key-piece of
4 feet, with one or two segments at each side completing the circle of the
required dimensions. In order to form a smooth surface inside the tube the
several segments are secured to each other by dovetailed wedges. These
wedge fastenings may be made of malleable iron or steel. They may be
formed in bars of any convenient length, and cut into the required sizes for
use, and formed so as to have a slight draw in order to bring the edges of the
segments close together. I form the edges of the plates with a double bevel,
thickened at the junctions if necessary, so that they will not pass each other by
pressure or during the driving of the wedges. The strengthening ribs will in
this case be on the outside of all the castings. The work being carried on under
the river or estuary until water gets into the works, I fit two air-tight valves
in the tube, the one at or about the water level, and the other at a convenient
distance above. I force air into the portion of the tube from the upper valve
to the end of the heading, the density of which would depend upon the head
of water to be contended against. The distance between the two valves is
employed as an air chamber or 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 this air chamber,
the upper valve will then open, and the lower valve remain shut. A quantity
of materials in the trucks hereafter described and the required number of men
are then introduced into the chamber cr lock, the upper valve is shut and air
admitted from the portion of the tube from the lower valve to the face of the
work, or forced in by the engine, and when an equilibrium is established the
lower valve will open and the materials can be taken to the works. The ex-
cavated materials may be easily disposed of by laying downtemporary rails on a
guage of about two feet six inches, and by adopting small waggons, several of
which loaded may be drawn into the air lock, the lower valve shut and the air
allowed to escape from the lock, when the uppervalve will open andthe waggons
be drawn out. The materials can then be sent in by the return waggons
and the process continued in this way at each end of the tube until complete.
I now proceed to describe an arrangement or plan 1 adopt for removing the
excavated material from an atmospheric tunnel,or from a common heading in
an ordinary tunnel, and also for sendingin building materials. I employ trucks
may

page_text: of light material, but strongly and neatly put together, with four low wheels
running upon an ordinary tram or railway. The dimensions may be made to
suit the nature of the work, but 5 feet long, four feet broad, and rather
more than two feet deep will be sufficient for ordinary purposes. The top of
each side of each truck has a slight angle iron screwed down upon it to act as
a rail or tram to pass the empty trucks over the full ones; the trucks being
so constructed that the breadth of the guage between the upper edges of each
truck is the same as the guage of the tramway along the bottom of the tunnel
or heading. Iemploy two light rails, which may be framed together or remain
separate, the upper end of each being hooked to the upper angle of the truck,
and the lower end so embracing the ordinary rail as to be kept in position,
but allowed to move in any direction along the rail with the truck. These
rails may be of any convenient length, and are for the purpose of enabling an
empty truck, say truck No. 2, to be drawn over truck No. I when filled. I
attach similar rails to the other side of truck No. 1 for the purpose of
lowering truck No. 2 from the top of truck No. 1 to its position at the face
of the work to be filled. When No. 2 is filled the inclined rails between
Numbers 1 and 2 are removed, and No. 2 is pushed close up to No. 1,and they
are attached to each other by a simple hook and staple at each side about the
centre of the height. The inclined rails are then hooked to the upper angle
of No. 2, and truck No. 3 is brought over Nos. 1 and 2, and in this way the
process is continned until any convenient number of trucks are filled. The full
trucks are then to he drawn away, and the material may be deposited in an
embankment, or the trucks may be drawn up a shaft, either with or without
the wheels as may be most convenient: When the excavated material is
disposed of in a narrow embankment the empty trucks may be passed from
the tip over the full ones in the reverse manner to that already described.
For working an atmospheric tunnel or tube under a river or estuary one
in fifty, I employ two accumulators, one at the summit of each incline. At each
of these points I place an engine. The descending gradients will always be
worked by gravitation, that is to say, a train starting from one summit will
have the valves or openings in the diaphragms open, so that the atmospheric
air will pass freely from the front to the rear of the train, and thus the train
will descend as freely as it would do in the open air. Should the gradient be
too steep for the safe descent of the train, instead of using breaks to avoid too
rapid a descent I obtain the same result by shutting the valve behind the
train and regulating the openings in the diaphragms, so as to keep full com-
mand of the train. Steep inclines may be worked, as already explained in
reference to passing over mountain ridges, and advantage may also be.taken

page_text: to make a partial vacuum in the accumulators by the descent of the train.
To prevent the possibility of an accident I do not place a valve at the bottom
of the inclines. The momentum acquired by the train in descending one
incline will carry it some distance up the opposite incline, and before the train
is allowed to stop I commence to work the engine at the top of the second
incline to extract the air from the front of the train. I then open the
connection with the accumulator to expedite the ascent of the train.
The next part of my Invention relates to the stations intermediate and
terminal. I continue the tube or tunnel of the same form at the station as
at any other portion of its length by a casing consisting partly of fixed portions
and partly of doors which will open on the platform, and when as at inter-
mediate 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 can step out of the
carriages on to the platform. At terminal stations it may frequently be more
convenient for the trains to run out of the tube into the open air, and up an
incline when convenient.
The next part of my Invention relates to means of rarefying and condensing
air for working atmospheric railways and tubes. The general principle upon
which this part of my Invention is based is that the air is not "wiredrawn,"
as it is in the air pump by passing through valves, nor is it expelled by violent
concussions as in fan blowers, but it is drawn out in a full volume of the
density of the tunnel or tube from which the air is extracted, and no power
is expended in forcing the air through narrow apertures, nor in expelling it
by a rapid succession of blows. I employ at the mouth of the tunnel or
tube revolving discs, each carrying four feathering fan blades. The division
between the external atmosphere and the tunnel is formed by a casing parallel
to the discs joining a diaphragm which extends close to the revolving axle of
the discs, and one or other of the fan blades extending from the axle to the
invert of the tunnel. The discs are formed of a strong iron framing con
sisting of a rim and several cross bracings, the principal pieces being at right
angles to each other. Four pieces forming a square in the interior of the
axle extend the whole length of the axle, firmly connect the discs, and form
the principal strength of the axle. At each end a block of hard wood is
inserted between these four pieces, into which the gudgeons or journals of the
axle are inserted and firmly secured by bolts and hoops. The revolving discs
pass through slits in the diaphragm, and before any one of them arrives at
these slits or openings it is feathered so as to become symmetrical with the
discs. The iron skeleton or framework of the discs, as well as the feathering

page_text: fans, are filled out with wood or other suitablematerialtoa uniform thickness,
in order that the slits in the diaphragm may be at all points in the revolution
of the discs so filled as to prevent the ingress of external air. The axle is
also filled with suitable material to complete the circle. The fans are turned
a quarter round, or feathered by means of toothed racks gearing into toothed
pinions attached to the pivot of the fans. The toothed racks are acted upon
by wedges or inclined planes attached to the inside of the casing of the
revolving discs, and by the ends of these racks coming in contact with the
inclined planes they are moved horizontally at those points in the revolution
of the discs where the fans are required to change position. The fans turn
on pivots in connection with the rims of the discs and with the iron framing
of the axle. The diaphragm can be strongly braced from the casing between
the revolving discs.
This machine may also be used for condensing air in an atmospheric
tunnel, or it may be employed under any circumstances where atmospheric
air is required to be exhausted or condensed for any purpose.
Instead of the arrangement of racks and pinions for feathering the fans, I
sometimes place a small friction roller upon each of theoutwardanglesofeachof
the fan blades, and extending beyond the outer edge of the discs. When a fan
arrives at the position where it is required to be feathered, one of its friction
rollers comes in contact with an inclined plane which passes all round the
disc with two short interruptions, only portions of it are in the sameplane with
the disc. The fan is thus gradually turned on its pivots by the friction roller
pressing against the inclined plane, until it folds into andis symmetrical with
the disc so as to pass through the slit in the diaphragm. The axes of the two
friction rollers fall into notches in the disc; when the fan arrives at the point
where it is completely folded into the discs, the plane upon which thefriction
roller presses ceases to be an inclined plane, and becomes parallel to the disc,
so as to retain the fan in the plane of the disc until it passes clear of the
diaphragm. After the fau has passed the diaphragm one of its friction rollers
comes in contact with an inclined plane which continues to rise until it
arrives at the point where it commences to draw air from the tunnel, when
the fan comes against stops placed on the axle on opposite sides of the fan,
so as to brace it strongly against the pressure of the air. From this position
the friction rollers run on a plane parallel to the plane of the disc until
the fan again requires to be feathered.
In another arrangement of air extractor and condenser I construct at the
mouth of the tunnel or space from which the air is to be extracted a hollow
cylinder of any convenient length, and constructed of wood, iron, or any other

page_text: suitable material; stone or brick walls would be preferable to any other mode
of construction for the ends. Inside this cylinder another hollow cylinder or
drum is free to revolve upon an axis supported in the walls forming the ends
of the larger cylinder, and fitting as close as possible at the ends and at the
top; the gudgeons or journals pass through the walls and are acted upon by a
wheel and band or by a crank. I fix six or other convenient number of fans
extending the whole length of the drums, and formed of wood or iron. The
funs diametrically opposite to each other are connected together by two or
more iron or steel rods; these rods pass through the axle of the smaller drum,
or are connected by two parallel rods passing one on each side of the axle,
assuming different positions along the length of the axle so as not to interrupt
each other nor too much weaken the axle at any point. The fans are kept
in their radial position by sliding in grooves formed on the insides of the ends
of the smaller drum. The fans are carried round by the revolving drum, and
at each of the outward angles of each fan a small friction roller is placed
which presses lightly against the interior of the larger cylinder and more
closely on that portion of the cylinder on each side of the top, so that the
opposite fans while employed in expelling or condensing the air may be kept
close to the curve against which they bear. The large cylinder is open at its
periphery except at this curve and at the portion diametrically opposite, but
where it is open I provide a circular margin for the friction rollers to act
against, or the end walls of the large cylinder may be built up and recessed a
few inches back in the form of the figure of the large cylinder; the friction
rollers then run round in these recesses the whole distance. While the fans
are passing through the semicircle from the bottom to the top of the cylinder
the friction rollers on their ends have to act against an acute angle, whilst the
friction rollers in the opposite semicircle act against obtuse angles; there is
consequently much more friction in the former case than in the latter. This
objectionable friction may be got rid of by the following arrangement of
friction rollers:-A strong circular ring is firmly attached to the walls form-
ing the ends of the larger cylinder and projecting from the plane of the
walls about 2 inches, and upon each side of this projecting ring a friction
roller is placed. being attached to the outward angles of each fan; this ring
only extends over the semicircle through which the fans pass in their
downward movement or a few inches more at each end, but not over the
opposite semicircle.
I use the fans in this construction detached from the opposite fans, each
fan acting independently of the others. In this case the diameter of the re-
volving cylinder or drum and the air space below it must be so proportioned

page_text: that the fans have a sufficient hold in the slides formed in the revolving drum
when they are projected to the greatest distance from it; in this arrange-
ment the ring and friction rollers extend the whole distance. In either of
the arrangements the fans may be fixed instead of movable or feathering.
I lay down in atmospheric tunnels one central rail, and construct the
carriages with wheels in the middle to run upon this single line of rail;
this mode of construction, both of carriage and permanent way, is designed
for the purpose of passing round very sharp curves, such, for example, as
that of passing in a tunnel from one street to another when they are placed
at right angles to each other.
The
I prefer to construct the tunnel of stone, brick in cement, or glazed tiles
backed with concrete. A stone is placed at the centre of the invert to
which the centre rail is firmly bolted, the bolts passing through the stone
and being connected by a small bar of iron at the bed of the stone.
rail is, by preference, of the flat-bottomed description with a strong base,
and is bolted down to the stone block with a longitudinal timber partly let
into the stone upon which the rail is placed. I build bond timbers into the
work at the sides of the tunnel with a plate of iron screwed on to the face
of the wood, against which friction rollers attached to each side of the
carriages run, these friction rollers are adjusted to admit of very little lateral
play in order that the carriages may move steadily along the tunnel on the
centre rail. Where there are very sharp curves the carriage, which will
virtually be one continuous structure, should be divided into short lengths
closely attached to each other by universal joints. The seats may be formed
along the centre of the carriage over the central wheels.
Another method of constructing a tunnel to receive a single line of rail is
to form the cast-iron invert at the bottom with projections forming a dove-
tailed recess in which longitudinal pieces of wood beveled on one side are
placed in pairs, and between the two pieces of each pair a piece of hard wood;
the grain of the wood running vertically is driven in tightly. This piece
projects to fit into a bridge rail held down by wood screws, and tends to
retain it in its position. The carriage is held in an upright position by
friction rollers at the top running against a projection cast upon the upper
or key portion of the cast-iron tunnel; this cast-iron projection may, how-
ever, have substituted for it a strong malleable iron string piece of
the T-form bolted to the soffit of the tunnel. Guide wheels may also be
employed at the sides, as in the arrangement last described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Doull in the Great Seal Patent Office on
the 9th June 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
DOULL, of Westminster, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of December, in the year of our Lord
One thousand eight hundred and sixty-five, in the twenty-ninth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Alexander Doull, Her special licence that I, the said Alexander
Doull, my executors, administrators, and assigns, or such others as I, the
said Alexander Doull, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE
MENTS IN CONSTRUCTING ATMOSPHERIC RAILWAYS AND CARRIAGES, AND IN WORKING
THE SAME, PARTS OF WHICH ARE APPLICABLE TO EXHAUSTING AND CONDENSING AIR
FOR OTHER PURPOSES," upon the condition (amongst others) that I, the said
Alexander Doull, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Alexander Doull, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the follow.
ing statement thereof, reference being had to the Drawings hereunto
annexed, that is to say:-
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 allow the passenger carriages and
luggage vans to pass through. but not the locomotive engine. The permanent
wayis of the same description as that on the locomotive line with which theincline
is connected. The atmospheric tube when intended for a purely atmospheric
line, and when it is above ground or partly above ground, or when under the

page_text: bed of a river or estuary is constructed as hereinafter explained.
A dia.
phragm carriage is placed in the front and another in the rear of the train or in
any other convenient position. These carriages are generally constructed
upon four wheels with breaks attached. The diaphragms are formed so that
the base will fill the tube or tunnel of whatever shape it may be made, leaving
a small space all round. The outline of the diaphragm is generated by a
semi-revolution of one-half of the figure formed by a cross section of the tube
upon its vertical axis, slightly modified when the base of the tunnel is a
straight line or nearly so; I do not, however, confine myself to this particular
form. The space around the diaphragm is filled by a fringe of any soft or
elastic substance, which being attached to the inside of the diaphragm lies
against the inside of the tube at a very oblique angle. The diaphragms are
formed of thin metallic or other substance, and strengthened by ribs, and they
are constructed so that portions of them will open or fold up in order to throw
off the propelling power when necessary. When however an incline on each
side of a mountain range is very steep, say one in ten, or even still higher, I
work the trains over the summit in the following månner: -I construct an
atmospheric tube or tunnel as shewn in the sketch Figure 1 of the accom-
panying Drawings; A, B, C, D, is the atmospheric tube which is carried over
the summit of a mountain range or other elevation. In the tube at the
bottom of each side of the mountain I place a valve or folding air-tight door
A and D, forming an angle pointing outwards, as shown. Near the summit
of the mountain I place two engines B and C, one for each half of the tube.
Each engine is provided with an apparatus for withdrawing the air from the
portion of the tube on one side of the mountain as well as from an accumu-
lator E, also arranged at the summit of the mountain. This accumulator is
an air-tight space or vessel formed of any shape, so that the greatest amount
of internal capacity may be obtained with the least expenditure of labor. I
take advantage of any natural cavern which may exist at or near the summit
of the mountain, and line it if necessary so as to make it air-tight. When it
is required to start a train from the bottom to the top of the mountain, as
from A to B, a diaphragm carriage A¹ is placed in the tube as near to the
valve at A. as may be convenient, and the air contained in the small space
between the diaphragm carriage and the valve is allowed to escape by opening
an aperture in the valve into the vacuum in that portion of the tube A, B,
from which the air has been extracted by the engine at B. The pressure on
each side of the valve at A being thus equilibrated it is easily opened, and
the train attached to the diaphragm carriage will proceed up the incline at a
velocity proportioned to the extent of the vacuum and to the other circum-

page_text: stances of the case. If the vacuum is very high the speed would be very
rapid for some considerable distance, or until the air by the progress of the
train became condensed faster than the engine could extract it. The air is
then allowed to rush into the accumulator from the tube, which greatly assists
the engine, and accelerates the progress of the train to the summit. A
diaphragm carriage is also placed behind the train to prevent the possibility of
an accident should the coupling chains of the carriages give way in ascending
the incline. The connection of the tube with the engine B and with the
accumulator E is placed at a sufficient distance back from the summit valve F
to allow space for the condensation by the diaphragm of a cushion of air to
assist, in addition to the breaks, in stopping the train when necessary. There
are two valves placed in the tube at the summit both pointing outwards,
or there is only one valve constructed to resist pressure in both directions.
When the descending train passes into the portion of the tube between C
and D on the opposite side of the mountain the valve at F is shut behind it,
so that the diaphragm forms a vacuum in the tube behind the train; the
progress of the train will therefore be very slow on account of the atmo-
spheric resistance; the air in the accumulator E, which may be considered as
at the density of the atmosphere, is then permitted to enter the vacuum in
just sufficient quantities to allow the decending train to move at a safe speed.
When the supply of air from the accumulator E to the rear diaphragm of
the descending train is exhausted, and a partial vacuum is thus formed in
the accumulator, the accumulator is shut in order to preserve the vacuum,
and air is then admitted from the front of the train to the rear through valves
arranged for the purpose in the diaphragms, and the quantity of air which
is thus allowed to pass from the plenum in front of the train to the partial
vacuum behind it governs the speed of the train. But in order to guard
against the possibility of an accident to the train in its descent the valve at
the bottom D of the tube is kept closed and is opened only by the motion of
the train when it approaches sufficiently near for that purpose. When the
accumulator E bas been shut after the descent of the train the engine B on
that side of the summit which the train has previously ascended commences
to extract the air from the accumulator E, and the other engine C commences
to extract the air from its portion of the tube so soon as the train has passed
through the valve at the bottom D preparatory to the ascent of a train in
. the opposite direction or from D to C. Should the traffic on a line of this
description be very considerable there would be no difficulty in arranging a
place at the summit of the mountain for the trains to pass each other. In
a country where there is an elevated mineral district with a heavy traffic

page_text: descending, and little more than empty trucks ascending, the traffic could
be worked very economically, being the partial vacuum left in the tunnel
by a descending heavy train would take up a light train with some assis-
tance from the engine and the accumulator at the summit.
Another part of my Invention relates to the construction of a continuous
carriage, or rather carriage body, without wheels or axles. This continuous
carriage is constructed in short joints or lengths, depending upon the radius
of the curves to be passed round. The principal parts of the structure consist
of two longitudinal pieces of framing C, C, Figures 2 and 3, which may be
composed of wood or iron of the T-form or other suitable figure or dimensions,
framed parallel and about three feet apart, the cross framing supporting the
flooring of the carriage. There is a passage along the centre of the carriage
with seats on each side of the passage. The several portions or lengths of
the carriage are rigidly attached to each other at a central point D by an
universal joint, and the longitudinal pieces of framing C must be continuous
as they have to pass over parallel sets of friction rollers B, B, placed about
five feet apart longitudinally; they should also be 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 at D. These articulations are formed by
alternate tongues and recesses formed on each of two adjoining pieces of
framing which fit into each other. They draw out on one side and push in on
the other side,according to the direction of curvature, and they are sufficiently
long to preserve the continuity of the bearing surface on the friction rollers.
When the line is straight the frame C, C, remains as represented in Figure 3,
the tongues E,E, forming a continuity of bearing surface for the purpose of
passing over the friction rollers, and in passing round a curve either to the
right or to the left the tongues E,E, pass in opposite directions into or out of
the corresponding recesses F,F. In order to prevent the tongues from passing
each other vertically in consequence of any pressure to which they may be
exposed in that direction they are tongued and grooved into each other, but
free to move laterally and to some extent vertically. The extent of lateral
motion which it is necessary to provide for in any particular case is deter-
mined by the radius of the sharpest curve on the line, and in passing ro ind
very sharp curves the flexible joints should occur more frequently. The por-
tion of the floor of the carriage from the centre D outwards which would be
opened by the arrangement just described is covered by an overlapping
board fixed at one side only, or by vulcanized india-rubber. The whole train
s virtually one continuous carriage with a passage along the centre from one

page_text: end to the other, except that it is divided into the usual number of classes
with separate entrances to each. The carriages are, by preference, constructed
of the lightest material consistent with the necessary amount of strength.
They may, however, consist of a strong framework with high-backed sofas on
each side of the longitudinal passage. The doors are made to slide into or
along the side of the framing of the carriage. One entrance may, how-
ever, be sufficient at the end of each class of carriage, in which case the
ordinary doors may be altogether dispensed with. The tube or tunnel when
intended for a purely atmospheric line may be of any suitable shape or size,
but I prefer a circular form of about seven or eight feet in diameter. It may
also be formed of any available and suitable material, such as brick, stone,
ashlar, or rubble, and if of the latter the tube should be smoothly plastered
on the inside. I prefer, however, to use a cast-iron invert, as shown in
Figure 2, cast in five feet lengths and imbedded in concrete, the several
castings to be well joggled and bolted together. On each casting there are
two projections A, A, one on each side and about three feet apart,and formed
to receive the friction rollers B, B, upon which the train is propelled by
atmospheric pressure. There are also longitudinal projections H,H,Figure4,
between these projections in order to form a continuous and symmetrical pro-
jection for the guide wheels G, G, Figure 2, 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 pro-
tions of the tunnel may be constructed of stone, brick, or any suitable
material. In passing under rivers or estuaries the tunnel may be most
advantageously completed in cast iron, put together in segments as hereafter
described. The invert may, if preferred, be composed of 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 relates to the construction of the atmospheric tunnel
or tube when it is partly or altogether above ground. It is composed of
malleable iron ribs rolled into an H shape, as shewn in cross section in
Figure 5, and of sufficient strength to resist internal and external pressure.
These rolled bars are bent to the required shape, placed about 3 feet
apart with occasional cross ties, and the spaces filled in with wood,as shewn
in the longitudinal section, Figure 5, or with slate, flag, glass, earthenware, or
other suitable material, and when completed the whole is asphalted or tarred
over and covered with brown paper or other material, so as to render
the tunnel air-tight. When the filling-in is composed of glass it may be
desirable to leave the glass exposed so as to obtain light in the tunnel. This

page_text: mode of construction is peculiarly applicable in changing an underground
railway, whether in a tunnel or with portions in a deep open cutting, into
two or three atmospheric tubes. When these tubes pass through a tunne]
the space between them and the top of the tunnel is available for and I
employ it as an accumulator for rarefied air to be used in the economical
working of the trains.
I construct an atmospheric tunnel or tube under a river or estuary in the
following manner, see Figure 6:-The work is accurately set out, and the
cast-iron invert adopted as already described; the tube is completed by
strong castings put together in convenient segments, with the flanges bolted
inside. This mode of construction necessitates the subsequent adoption of
a thin smooth lining of wood or metal applied to the inside of the tube,
with the exception of the invert. The joints are made air and water tight
in the usual way.
same.
I also adopt the following mode of securing the several segments of the
cast-iron tube together -The tube being, say, seven or eight feet in
diameter, is divided into four or six segments, one invert of four feet, with
one or two segments at each side, and an upper or key piece of four feet
completing the circle of the required dimensions. In order to form a smooth
surface inside the tube the several segments are secured to each other by
dovetailed wedges, A, Figure 7, being an elevation, and B, a section of the
These wedge-shaped fastenings may be made of malleable iron or
steel. They may be formed in bars of any convenient length, and cut into
the required sizes for use, and shaped so as to have a slight draw, in order
to bring the edges of the segments close together. I form the edges of the
plates or castings with a double bevel, thickened at the junctions when
necessary, so that they will not pass each other by pressure or during the
driving of the wedges, as shown at B, Figure 7. The strengthening ribs in this
case are on the outside of the castings. The work being carried on under the
river or estuary until water gets into the works, I then fit two air-tight valves
D and E, Figure 6, in the tube, one at or about the water level and the other
at a convenient distance above it. I force air into the portion of the tube
from the upper valve E to the end of the heading, the density of which will
depend upon the head of water to be contended against. The distance
between the two valves E and D) is employed as an air chamber or 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 chamber D, E, the valve E will then open and

page_text: the valve D will remain shut. A quantity of material in the trucks, here-
after described, and the required number of workmen are then introduced
into the chamber or lock 1), E, the valve E is next shut and air admitted
from the portion of the tube from D to the face of the work, or forced in by
the engine, and when an equilibrium is established the valve D will open and
the materials are taken to the work. The excavated materials may be easily
disposed of by laying down temporary rails on a guage of about two feet
six inches, and by employing small waggons, several of which, when loaded,
may be drawn into the air lock; the valve Dis then shutand the airallowed to
escape from the lock, when the valve E will open and the waggons may be
drawn out. Materials can then be sent in by the return waggons and the pro-
cess continued in this way at each end of the tube until the work is completed.
I now proceed to describe an arrangement or plan for removing the
excavated material from the atmospheric tube or from a common heading in
an ordinary tunnel, and also for sending in building materials. I employ a
series of trucks, as shown in Figure 8, of light material, but strongly and
neatly put together, with four low wheels running upon an ordinary tram or
railway. The dimensions may be made to suit the nature of the work, but
five feet long, four feet broad, and rather more than two feet deep will be suffi-
cient for ordinary purposes. The top of each side of the trucks has a slight
angle iron screwed down upon it to act as a rail or tram to pass the empty
trucks over the full ones; the trucks being so constructed that the breadth
of the guage between the upper edges of each truck is the same as the
guage of the tramway along the bottom of the tunnel or heading.. I employ
two light rails A, which may be framed together or remain separate; the
upper end of each being hooked to the upper angle of the truck, and the
lower end so embracing the ordinary rail as to be kept in position, but allowed
to move in any direction along the rail with the truck. These rails may be
of any convenient length, and are for the purpose of enabling the empty truck
Number 2 to be drawn over truck No. 1 when filled; and the incline B,
which is similar to A, is for the purpose of lowering truck 3 from the top of
truck 1 to its position at the face of the work to be filled. When truck 2 is
filled the inclined rails B are removed, it is pushed close up to truck 1, and
they are attached to each other by a simple hook and staple at each side
about the centre of the height. The incline B is then replaced, and truck 3
is then brought over trucks 1 and 2, and in this way the process is continued
until any convenient number of trucks are filled. The full trucks are then
drawn away and the material may be deposited on an embankment, or the trucks

page_text: may be drawn up a shaft, either with or without the wheels as may be
most convenient. When the excavated material is deposited on a narrow
embankment the empty trucks may be passed from the tip over the full
ones in the reverse manner to that already described.
For working a train through an atmospheric tunnel or tube under a river
or estuary I employ two accumulators D and E, as shown in Figure 9, one at
the summit of each incline, and at each of these points I place an engine.
The descending gradients A to B and C to B are always worked by gravity,
that is to say, a train starting from A to B should have the valves or openings
in the diaphragms open so that the atmospheric air will pass freely from the
front to the rear of the train, and thus the train will descend as freely as it
would do in the open air. Should the gradient be too steep for the safe
descent of the train, instead of using breaks to avoid too rapid a descent I
obtain the same result by shutting the valve behind the train at A, and regu-
lating the openings in the diaphragm, so as to keep full command of the
train. Steep inclines may be worked, as already explained in reference to
passing over mountain ridges, and advantage may also be taken to make
a partial vacuum in the accumulators D and E by the descent of the train.
To prevent the possibility of an accident I do not place a valve at the
bottom B of the incline. The momentum acquired by the train in descending
one incline will carry it some distance up the opposite incline, and before
the train is allowed to stop I commence to work the engine at the top of
the incline towards which the train is approaching to extract the air
from the front of the train; I also open the connection with the accumu-
lator to expedite the ascent of the train.
por-
Another part of my lavention relates to the stations, intermediate and
terminal. I continue the tube or tunnel of the same form at the station as
at any other portion of its length, by a casing consisting partly of fixed
tions and partly of doors which will 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 can
step out of the carriages on to the platform. At terminal stations it may
frequently be more convenient for the trains to run out of the tube into the
open air, and up an incline.
The next part of my Invention relates to means of rarefying and condensing
air for working atmospheric railways and for other purposes. The general
principle upon which this part of my Invention is based is that the air is not

page_text: wiredrawn as it is in the air pump by passing through valves, nor is it ex-
pelled by violent concussions as in fan blowers, but it is drawn out in a full
volume of the density of the tunnel or tube from which the air is extracted,
and no power is expended in forcing the air through narrow apertures, nor in
expelling it by a rapid succession of blows. One arrangement for this pur-
pose is shewn in Figures 10, 11, and 12; I employ at the mouth of the
tunnel or tube A revolving discs B, B, each carrying four feathering fan
blades C, D, E, F. The division between the external atmosphere and the
tunnel is formed by a casing H parallel or nearly so to the discs joining a
diaphragm I which extends close to the revolving axle of the discs, and one
or other of the fan blades E, F, extending from the axle to the invert G of
the tunnel, and the ends are enclosed partly by masonry walls and partly by
the casing H. The machine may be driven by a crank or by a wheel and
band. The discs B, B, are formed of a strong iron framing consisting of a
rim and several cross bracings, the principal pieces being at right angles to
each other. Four pieces forming a square K, K, K, K, in the interior of the
axle extend the whole length of the axle, firmly connecting the discs, and form
the principal strength of the axle. At each end a block of hard wood is
inserted between these four pieces of iron K, into which the gudgeons or
journals L, L, Figure 11, of the axle are inserted and firmly secured by bolts
and hoops. The revolving diacs pass through slits in the diaphragm I, and
before any one of them arrives at the slits or openings it is feathered, so as to
become symmetrical with the discs. The iron skeleton or framework of the
discs, as well as the feathering fans, are filled out with wood or other suitable
material to an uniform thickness, in order that the slits in the diaphragm may
be at all points in the revolution of the discs so filled as to prevent the ingress
of external air. The axle is also filled out with suitable material to complete
the circle. The fans C, D, E, F, are turned a quarter round or feathered by
means of toothed racks N, N, Figures 10 and 12, gearing into toothed pinions
M, M, attached to the pivots of the fans. The toothed racks are acted upon
by wedges or inclined planes attached to the inside of the casing of the
revolving discs, and by the ends of these racks coming in contact with the
inclined planes they are moved horizontally at those points in the revolution
of the discs where the fans are required to change position. The fans turn
on pivots in connection with the rims of the discs B,and with the iron framing
K of the axle; the diaphragm I may be strongly braced from the casing H
between the revolving discs. This machine may also be used for condensing
air in an atmospheric tunnel, or it
may be employed under: any
circumstances

page_text: where atmospheric air is required to be exhausted or condensed for any
other purpose, as for ventilation or for blowing air.
In another arrangement of air extractor and condenser,shown in Figures 14
and 15,Iconstruct at the mouth of the tunnel A or space from which the airis to
be extracted, or into which the air is to be condensed, a hollow drum or cylinder
B,B; thedrum may be constructed of any convenient length and placed horizon-
tally, and may consist of wood, iron, or any other suitable material. This drum
revolves on an axis O which is supported by a cast-iron or wooden frame Pat
each end of the drum. The dotted circle H represents a groove cut in the fixed
supports in which the drum revolves, and when these supports are composed of
iron the groove is sunk into the metal, or when the supports are composed of
wood a metallic ring with the groove cut in it is attached to the frame. The
circle His excentric to the drum; K, K, are six or other convenient number
of fan blades which are projected from the drum when passing below it, and
drawn into it when passing round the highest point in the revolution of the
druin. This motion of the fan blades is effected by means of pins m projecting
from the inner edges of the fans running in the excentric groove H. n, n, are
slits cut through the end casing of the drum to allow the pins m to pass
into the excentric groove H. I construct the drum as follows:-The ends
are of cast or malleable iron of any convenient thickness, and to the inside of
these end discs metallic slips are attached for the purpose of guiding the fans
in their motion into and out of the drum. The casing of the drum may be of
metal or wood and accurately filled out to the circular line B, B, but the end
discs of the drum project as shown by the dotted external circle, and the
edges of these discs are turned true, so as to run air-tight in a recess in
the end supports of the dram at T. The end supports P of the drum extend
to the invert, the mouth of the tunnel, and the casing R, R, which together
with the portion of the drum (farthest from the tunnel), from the highest
point to the fan in contact with the invert S constitute the division between
the rarefied or condensed air, as the case may be, and the external
atmosphere. From the furthest point of the invert (from the tunnel,) to
the top of the drum, where it is pressed by the casing R is open to the
external atmosphere, all other parts being closed against it. The drum is
driven round by a crank or wheel and band by steam or other power.
Figure 18 is a section, and Figure 19 is an elevation showing another
rrangement for rarefying and condensing air. The fans K, K, in this case
re not made to slide into the drum, as in Figure 14, but to fold round it,
he fans having the same curvature as the drum. The drum A, B, C¹, D¹, in

page_text: this mode of operation is a fixture, and does not revolve as in the former case.
A. B, C, D, and F, represent two discs, one at each end of the drum. These
discs may be made of cast or malleable iron or of wood of any convenient
thickness. The fans, which extend the whole length of the drum,are attached
at equal distances to these discs, as at B, C, D, E. A portion of the outer
edge of each fan passes through the discs at each end of the fan and fit accu-
rately, but so as to turn round as the direction of the fans changes. When
the fans are composed of thin material, as copper, steel, or iron, a stouter
piece of iron extends along the outer edge of the faus and forms the pivots
fitted into the discs at each end of the fans; and in order to brace the whole
revolving cylinder of fans and discs firmly together short braces extend from
the discs at each side of the rods above described along the outsides of the
fans, forming the hypothenuse, of any convenient length, to the right angles
formed by the discs and the fans. These braces, although perfectly rigid, are
so attached to the back of the fan as to admit of the slight motion of the fan
which it must necessarily make in passing round the fixed drum. The fans
are attached to the fixed drum by two dovetailed or rectangular grooves
passing round the drum, one of which is shown at L, Figure 19. The fans
are attached to a steel pin inside the groove in such a manner as to keep the
fan close to the drum, and also to admit of the change of direction of the fans
with reference to the drum. Into the wall I an iron axle H is firmly fixed,
upon which the disc F revolves. This fixed axle is carried beyond the disc,
and upon the squared end of it the drum is built. This is effected by placing
a cross H¹ on the end of the axle and filling out the drum with wood. The
drum may also be formed by solid circular ends of metal or wood supporting
a thin circular covering, and prevented froni turning round by being supported
at each end on the square projecting end of the axle H. The wheel G is
attached to the disc F for the purpose of turning the disc and fans round;
it may either be smooth and driven round by a band from a steam engine or
other moving power, or it may consist of a toothed pinion driven round by a
large spur wheel.
From A, B, C, D, the discs run in a groove or recess
and thus constitute the air-tight ends of the machine. The circular cover A
extends from one disc to the other, and with the tunnel and invert complete
the division between the rarefied air and the external atmosphere. The
ends of the fans are accurately fitted to the discs. I do not, however,
confine myself to the use of feathering or sliding fans, but upon the same
general principle as that already described I use fixed fans.
In constructing atmospheric tunnels I lay down one central rail, and cou-

page_text: A.
struct the carringes with wheels in the centre to run upon this single rail, as
shown in Figures 16 and 17. This mode of construction, both of carriage
and permanent way, is designed for the purpose of passing round very sharp
curves, such, for example, as that of passing in a tunnel from one street to
another when they are placed at right angles. I prefer to construct the
tunnel of stone, brick in cement, or glazed tiles backed with concrete.
stone is placed at the centre of the invert to which the central rail is firmly
bolted, the bolts passing through the stone and being connected by a small
bar of iron at the bed of the stone. The rail is, by preference, of the flat-
bottomed description with a strong base, and is bolted down to the stone
block with a longitudinal timber partly let into the stone upon which the
rail is placed. I build bond timbers A, A, into the work at the side of the
tunnel with a plate of iron screwed on to the face of the wood against which
friction rollers B, B, attached to each side of the carriage run. These friction
rollers are adjusted to admit of very little lateral play in order that the
carriages shall move steadily along the tunnel upon the centre rail. When
there are very sharp curves the carriages, which are virtually one continuous
structure, are divided into short lengths closely attached to each other by
universal joints. The seats are formed along the centre of the carriage over
the central wheels; C, C, are longitudinal pieces of timber or iron resting
upon the axles E, E, of two wheels, and upon these two pieces the carriage
is built, as shewn in the Drawing. The frame of the carriage is composed
principally of irou, and in many cases need not be carried higher than the
friction rollers. The distance between the wheels depends upon the
sharpness of the curves to be passed round by the carriages.
The
Another method which I propose of constructing a tunnel to receive a
single central rail is to form the cast-iron invert with projections B, Figure 17,
cast upon it forming a dovetailed recess, in which longitudinal pieces of
wood C¹ bevelled on one side are placed. A piece of hard wood I), the grain
of the wood running vertically, is driven in tightly between the pieces C', and
this piece projects and is made to fit into a bridge rail, and tends to retain
it in its position; the bridge rail is held down by wood screws.
carriage is held in an upright position by friction rollers E, F, running
against a projection cast upon the upper or key portion of the cast-iron
tunnel; this cast-iron projection may, however, have substituted for it a
strong malleable iron string piece of the T form bolted to the soffit of the
unnel. Guide wheels may be employed at the sides, as in the arrangement
ast described, instead of guide wheels at the top.

page_text: I also employ in the two last-described cases, Figures 16 and 17, at
or near the junctions of the inverts with the sides of the tunnels wheels at
each side of the carriages, placed at any convenient angle of obliquity, to
act partly as bearing and partly as guide wheels; these wheels when
employed would supersede the use of any other guide wheels or friction
rollers.
And having now described the nature of my said Invention, and in what
manner the same is to be performed, I declare that I claim as my "Improve-
ments in Constructing Atmospheric Railways and Carriages, and in Working
the same, Parts of which are applicable to Exhausting and Condensing Air
for other Purposes,"―
First, the arrangement or method, herein-before described with reference
to Figures 1 and 9, for passing a train of carriages or waggons over a
mountain range or under a river or estuary in a tunnel when the gradients
are too steep for a locomotive to pass with safety and economy.
Second, constructing atmospheric railway carriages in one continuous
length with flexible joints running upon friction wheels connected with the
invert of the tunnel and directed by guide wheels, all substantially as
herein-before described with references to Figures 2, 3, and 4.
Third, the arrangement or method, herein-before described with reference
to Figure 6, for excluding water from a heading or from a tunnel which is
being driven under a river or estuary by compressed air in connection with
an extensive air chamber or lock.
Fourth, the arrangement or method for withdrawing the excavated
materials from a heading in an ordinary tunnel or from a tunnel excavated by
the adoption of the air-lock principle, and also for sending in building
materials, substantially as herein-before described with reference to Figure 8.
Fifth, constructing an atmospheric tube or tunnel when above the ground,
or partly above and partly below the ground, substantially as herein-before
described with reference to Figure 5.
Sixth, the arrangements or methods for extracting and compressing air
for the purpose of atmospheric railway propulsion, or for exhausting or
condencing air for other purposes, substantially as herein-before described
with reference to Figures 10, 11, and 12, Figures 14 and 15, and Figures 18
and 19.
Seventh, constructing atmospheric railway carriages with central wheels
and with friction rollers or guide wheels, or with wheels placed obliquely
partly guiding and partly bearing, and constructing permanent way to be

page_text: employed in connection therewith, all substantially as herein-before described
with reference to Figures 16 and 17 of the accompanying Drawings.
In witness whereof, I, the said Alexander Doull, have hereunto set my
hand and seal, this Seventh day of June, in the year of our Lord
One thousand eight hundred and sixty-six.
ALEXR. DOULL. (L.s.)