IMPROVEMENTS IN STEAM ENGINES
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by Richard Archibald Brooman, at
the Office of the Commissioners of Patents, with his Petition, on the
12th December 1863. A communication from abroad by Victor Barbier,"
residing at Montbeliard, France.
I, RICHARD ARCHIBALD BROOMAN, of 166, Fleet Street, in the City of
London, Patent Agent, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN STEAM ENGINES," to be as follows:-
In this Invention the steam is retained in the cylinder when a part of its
heat has been converted into work, and when it has consequently lost some of
its elastic force, and its primitive tension is restored by the addition, through
chambers at the ends of the cylinder, of the same quantity of heat which was
lost in becoming converted into mechanical effect. In this arrangement of
steam engines there is no escape steam lost. I take steam from, say; a tubular
boiler, at its elastic force equal to that of seven atmospheres, but steam at a
higher or lower temperature may be used. In a steam eylinder I fit a piston
and piston rod, and connect it to a crank. The piston does not travel the
whole length of the cylinder. Steam enters the cylinder through a box; the
pipe leading into the box is furnished with a cock. In this box is a slide in
the shape of a plate of metal pierced with a hole in the centre. This aperture
is made to correspond with one or other of two channels, one leading to the
top and the other to the bottom of the cylinder. The slide is moved by an
excentric. There are steam pipes, furnished with stop-cocks, leading from the
boiler to each end of the cylinder, for the purpose of admitting steam to start
the engine. The cylinder is supposed to be placed horizontally, and the

page_text: boiler below it. Two chambers one at each end are formed at each end of the
cylinder for receiving the water which may become condensed in the cylinder,
and two pipes fixed in the steam inlet channels rise to a height less than that
of the chambers. The level of the condensed water cannot rise above the level
of the top of the pipes, but runs down them through the steam passages, and
returns to the boiler. While the crank is passing the dead point, steam enters
the cylinder at one end behind the piston, and is at the same pressure as that
in the boiler. As soon as the dead point has been passed, the slide shuts off
further supply of steam, and the steam in the cylinder drives the piston
towards the opposite end, but in proportion to the advance of the piston the
steam expands, and losing its elastic force and heat, which become converted
into work, at the same time the water condensed in the chamber at one end of
the cylinder becomes vaporised, and maintains the steam at its maximum
tension, which diminishes more and more until the piston attains the end of
its stroke. The lowering of the temperature arises from the water in the
reservoir in vaporizing absorbing heat, a part of which passes in a latent state
into the steam generated, at the same time that part of the heat contained in
the steam is converted into mechanical effect. The same takes place for the
return stroke, but the steam on the other side of the piston being driven back
by the piston becomes partly condensed on the piston reaching the end of its
return stroke; the space between the limit of its course and the end of the
cylinder contains steam which is reduced in temperature, and is only equal to
about four atmospheres. The engine has therefore used the difference and
converted it into work; it will suffice to return to the steam the degrees of
heat it had lost, and to restore it to its primitive maximum tension by the
addition of a small quantity of steam, in order that it may again produce the
same work. The slide opens communication between the boiler and cylinder,
equilibrium of temperature and pressure is restored, the steam absorbs the
same quantity of heat it had parted with, and its tension, which was only
equal to four atmospheres, is now equal to seven atmospheres; the dead point
passed the piston yields to the pressure of steam, which expands the water in
the vessel of the cylinder, vaporises, and the steam in the other part of the
cylinder is driven by the piston and condenses.