IMPROVEMENTS IN PROPELLING BY ATMOSPHERIC PRESSURE
Year: 1849

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALLEN BRAGG, of Queen's Row, Pentonville, in the County of Middlesex, Bath
Keeper, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Fourteenth day of March, in the twelfth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
William Allen Bragg, Her especial licence, full power, sole privilege and autho-
rity, that I, the said William Allen Bragg, my exors, adññiors, and assigns, and
such others as I, the said William Allen Bragg, my exors, adiñors, or assigns,
should at any time agree with, and no others, from time to time and at all
times during the term of years therein mentioned, should and lawfully might
make,. use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, my Invention of "IMPROVEMENTS IN PROPELLING BY
ATMOSPHERIC PRESSURE;" in which said Letters Patent is contained a proviso
obliging me, the said William Allen Bragg, by an instrument in writing under-
my hand and seal, particularly to describe and ascertain the nature of my said
Invention, and in what manner the same is to be performed, and to cause
the same to be inrolled in Her Majesty's High Court of Chancery within six
calendar months next and immediately after the date of the said in part recited
Letters Patent, as in and by the same, reference being thereunto had, will more.
fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Allen Bragg, do hereby declare that the nature of my said. Invention,

page_text: and the manner in which the same is to be performed, is particularly described
and ascertained in and by the following description thereof, reference being
had to the Drawings hereunto annexed, and to the letters and figures marked
thereon (that is to say) :-
The object of my Invention of improvements in propelling by atmospheric
pressure relates to a novel or improved mode of constructing atmospheric
railways, and propelling the carriages thereon. One of the great objections
and disadvantages of the atmospheric railways hitherto constructed is the
liability that exists of the longitudinal valve getting out of order and not being
air-tight, thereby occasioning a great loss of power. This has hitherto been
considered an objection of such magnitude that a variety of plans have from
time to time been devised for simplifying the construction of the valve and
rendering it more secure; and attempts have also been made to dispense with
the use of it altogether. Another great objection to the present system of
atmospheric propulsion is, that if by accident any small portion of the valve
should be out of order, the whole length of that section of the vacuum tube,
extending, perhaps, some hundreds or even thousands of yards, is rendered
inoperative and useless until the valve is repaired. The object of my present
improvements is to remove both of these objections; I, therefore, in. the first
place dispense with the use of the longitudinal valve; and in the second place,
instead of employing a continuous tube of great length, I divide the vacuum
tube into sections of any convenient length, such as twenty to twenty-five feet,
and arrange them in such a manner that in case one or more of these sections
should be accidentally deranged or put out of order, such an accident should
not materially interfere with the working of the railway, as the communication
with such sections may be cut off, and the defective vacuum tubes entirely
removed, without interfering with the remaining ones. In the accompanying
Drawings I have shewn a plan view, elevation, and section of my improved
arrangement of the vacuum tubes, and the means of working the same.
Fig. 1 is
a plan view. A, A, A, A¹, A¹, A', are the vacuum tubes arranged in
sets of three, and each of these tubes is furnished with a piston mounted on
the middle of a long piston rod a, a, the ends of which pass out through stuffing
boxes at each end of the vacuum tubes. Each end of the piston rods carries
a cross head or arm b, b, to which a long bar or rod B, B, is attached, and
lies parallel to the piston rod a, and vacuum tube A. At each end of this
bar or rod B, which I call the "propelling bar," and on the upper side thereof,
a series of notches, teeth, or indentations are made, as seen best in the side
view, Fig. 2. The vacuum tubes A communicate by means of short lateral
pipes with the exhausting pipes C, C, the other end of which is in connection

page_text: runs.
with a vacuum chamber or air pump, not shewn in the Drawing. This
exhausting pipe C is furnished with a number of valves c, c, and is only
intended to exhaust the tubes A from one side of the piston, and therefore
only acts when required to propel the carriage or train one way. A similar
exhausting tube C* communicates with the opposite side of the piston in the
vacuum tubes A, in precisely the same manner, and exhausts the latter when
the train or carriage is to be propelled in the opposite direction. By this
arrangement it will be seen that if, by any accident, either of the tubes A, A¹,
should be put out of order, it may be removed if thought necessary, and (care
being taken that the apertures of the short lateral pipes that communicate
with the exhaust pipes are properly stopped and made air-tight) no incon-
venience will result from the temporary removal of one or more of the vacuum
pipes. Upon referring to the Drawing it will be seen that the propelling bar
B is furnished with small supporting rollers 6', 6', which run on flat surface
laid down for the purpose, as seen best in Fig. 3, and is further supported by
other stationary antifriction rollers 6", 6", on which the said propelling bar
At or near each end of each of the vacuum tubes, and on the upper
side, is an aperture for the admission of air to the interior of the tube when
required. Each of these holes or apertures is furnished with a slide valve d,
which is acted upon by a projecting piece or frame attached to the under side
of the carriage, as will be hereafter explained. A weighted lever catch D is
placed at a suitable distance beyond the extremity of the vacuum tube A for
the purpose of catching hold and retaining the piston rod and propelling bar B
until they are required to act; one of these lever catches is placed at each
end of the tube, as shewn in the Drawing. The leading or propelling carriage
E, E, to which the other carriages of the train are attached, is furnished under-
neath with a projecting frame F, F, which carries a set of inclined propelling
levers f, f, or drag lever, shewn by dots at f* in Fig. 2. Now, supposing the
vacuum tube to be exhausted of air, and the pistons therein to be at or near
the right-hand end of the tubes, and held there by the lever catch D, the
action of the apparatus upon moving forward the carriage will be as follows:-
The end 1 of the projecting frame F will strike against the lever of the valve d
and will thereby open it, and allow air to rush into the vacuum tube behind
the piston, which will thereby be forced forward by the pressure of the air.
Simultaneously with opening the valve d, one of the propelling levers f will
have caught one of the teeth of the bar B, which, by the part 2 of the project-
ing frame F, F, coming against the upper end of the catch lever D, will be
liberated, as shown in the Drawing, and allowed to rush forward with the
piston, thereby drawing onward the carriage until another of the propelling

page_text: levers f, of which there are four, meets with the teeth of the second section of
a tube, when the same actions or operations will be repeated, and the carriage
carried on to the third section. When the piston in the vacuum tube bas
arrived at the end of its course the cross head or arm at the end of the piston
rod will catch against the lever D, and will be retained thereby, ready for
action when the train returns in the opposite direction.
When the carriage
or train is once started, it will in a short time have acquired such a momentum
by the successive actions of the propelling bars B thereon, that it will require
but little power to keep it in rapid motion, and therefore, in practice it may not
be found necessary to have so many vacuum tubes as are shewn in the Draw-
ing, except at all starting places and in ascending steep inclines.
I would here remark, that the exhausting tubes C and Care provided with
the valves c, in order to prevent the air that rushes into the vacuum tubes
through one of the valves d from passing through the exhausting pipe C or C*
into another of the vacuum tubes, and thereby destroying the vacuum therein.
It will be seen, however, that these valves, by opening upwards, will freely
allow the air to pass in the opposite direction, which it must do when the tubes
are being exhausted.
.
In Fig. 4 I have shewn a means of applying the pressure of air to work an
engine for propelling the main shaft of a steam vessel. a, a, are vacuum vessels
which are to be exhausted by means of a steam engine or other power, and
b, b, are two cylinders having pistons working in them which communicate with
the main or paddle shaft by means of the rod c, c; air pipes d, d, and e, e, lead-
ing from the vacuum vessels a, a, to each end of the cylinders, serve to exhaust
the latter when required, one of the pipes being made to communicate with
one side of the piston, and the other with the opposite side. These pipes are
furnished with cocks f, f, and h, h, for cutting off and opening the communi-
cation between the vacuum vessels and cylinders.
.
The operation of the apparatus is as follows:-Supposing the pistons in the
cylinders to be in the positions shewn by dots in the Figure, and a volume of air
to be on the upper side of the position, then, upon turning the cock f, the air
contained in the cylinder will rush therefrom along the pipe d into the vacuum
vessel a. It will be seen, upon inspecting the Drawings, that the cock f and
another cock g on the pipe e, are connected together by means of a rod, so that
when the cock f is opened the cock g will be opened at the same time, and
allow air from the atmosphere to rush along the pipe e to the under side of the
piston in the cylinder. In order to drive the piston down again the cocks
ƒ and g are closed, and the cock h on the pipe e, and the cock i on the pipe d,
are opened. From this it will be seen that by alternately opening and closing

page_text: the cocks f, g, and h, i, of the two cylinders, the pistons may be made to
work regularly up and down as in a steam engine, and will consequently drive
the paddle shaft. I would here observe, that the cocks f, g, h, and i, can be
worked by means of rods and excentrics connected with the crank shaft, or in
any other convenient manner.
Having now described my Invention, and the means of carrying the same
into effect, I claim as the Invention secured to me under the herein-before in
part recited Letters Patent propelling carriages on railways by means of the
propelling bars or shafts B, or other similar or analogous contrivances, such
bars or shafts being connected to pistons or piston rods working in or through
the vacuum tubes, the pistons in such tubes being acted upon and driven by
the pressure of the atmosphere on one side, while a vacuum is made on the
other and opposite side.
In witness whereof, I, the said William Allen Bragg, have hereunto set
my hand and seal, this Fourteenth day of September, in the year of our
Lord One thousand eight hundred and forty-nine.
AND BE IT REMEMBERED, that on the Fourteenth day of September, in
the year of our Lord 1849, the aforesaid William Allen Bragg came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifica-
tion aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according to
the tenor of the Statute made for that purpose.
Enrolled the Fourteenth day of September, in the year of our Lord One