STEAM 
bo further description of that part of the apparatus is neces¬ 
sary ; and as the two vessels on one side of the cylinder are 
precisely similar to those on the other, a description of the 
receiver, a , and the expansion vessel, c, will apply to their 
counterparts, b and d; the two former (a and c) are there¬ 
fore given in a separate figure in section, that their con¬ 
struction may be seen, and their operation better understood. 
The same letters of reference designate the like parts in both 
figures. 
The communication of the condensing pump (before- 
mentioned) with the receiver, a, is through the orifice, g, 
which can be stopped at pleasure by the plug or stop-cock, 
h. When the receiver has been charged with the liquid and 
closed, a pipe, i, is applied to and connected to the expan¬ 
sion vessel, c, at lc. II is a lining of wood (mahogany), or 
other non-conductor of heat, to prevent the absorption 
which would otherwise be occasioned, by the thick sub¬ 
stance of the metal. The expansion vessel is connected 
through a pipe, m, to the working cylinder, e; these vessels 
contain oil, or any other suitable fluid, as a medium between 
the gas and the piston. 
The receiver is a strong gun-metal vessel, of considerable 
thickness, in the interior of which are placed several thin 
copper tubes at ooo; the joints of these tubes through the 
top and bottom of the receiver are made perfectly tight by 
packing. The use of these tubes is to apply, alternately, 
heat and cold to the liquid contained in the receiver, with¬ 
out altering very sensibly the temperature of the cyliuder. 
The operation of heating and cooling through the thin tubes, 
ooo, may be effected with warm water, steam, or any other 
heating medium; and cold water or any other cooling me¬ 
dium. For this purpose the tubes, ooo, are united by a 
chamber and cock, p p, by the opening of which, with the 
pipes, oo, hot and cold water may be alternately let in and 
forced through, by means of pumps, the cocks being worked 
in a similar manner to those in steam engines. 
Now if hot water, say at 120°, is let in through the tubes 
of the receiver, a, and cold water at the same time through 
the receiver, b, the liquid in the first receiver will operate 
with a force of about 90 atmospheres, while the liquid in 
ihe receiver, b, will only exert a force of 40 or 50 atmo¬ 
spheres. The difference between these two pressures will, 
therefore, be the acting power; which, through the medium 
of the oil, will operate upon the piston in the working cylin¬ 
der. It is easy to comprehend that, by letting hot water 
through the receiver, b, and cold water through the opposite 
one, a, a re-action will take place, which will produce in the 
working cylinder, e, an alternate movement of the piston, 
applicable by the rod, f to various mechanical purposes as 
may be required. 
It is to be observed, that the use of the gasometer and of 
the forcing-pumps is simply for obtaining the gas, and for 
charging the receivers with the liquid. When the receiver is 
once charged, and has been closed with the stop-cock, h , the 
gasometer and forcing-pumps are to be disconnected from the 
receiver by unscrewing the pipe, i, at the joint. The same 
pipe may, however, be used as the means of connecting the 
receiver with the expansion vessel; the adoption of two dis¬ 
tinct pipes for these purposes is intentionally avoided, as it 
would become necessary in consequence to have two orifices, 
as well as two stop-cocks. It is obvious, that no difficulty 
exists in connecting the forcing pump with both receivers, 
as the small pipes used for that purpose may be made to reach 
either. 
The most essential parts of this interesting invention are— 
the internal application of the tubes for conveying the heat¬ 
ing and cooling medium; the cylindrical form, and the 
manner they are applied, rendering them capable of resisting 
the intense external pressure of the liquid, yet admitting of 
their being made so thin as to allow of the rapid and com¬ 
plete transmission of heat and cold through them; and the 
arrangements by which the receivers acting in opposition to 
each other produce, without any aid of intermediate valves, 
an alternating action, attended with scarcely any perceptible 
Vol. XXIII. No. 1591. 
ENGINE. ' 557 
diminution of power from friction, and bring into action a 
force so great, that it may almost be deemed irresistible. 
A machine on the same principle was invented by Mr. Che- 
verton, and about the same time as Brunei’s. It is not, how¬ 
ever, so simple nor of so elegant an appearance, but has so 
much merit, that we shall introduce Mr. Cheverton’a 
wordsHe says, “ I was, a few years ago, led by these 
views to turn my attention to the gases, having been forcibly 
struck with the prodigious pressure under which they are 
capable of being generated. Gunpowder, the fulminating 
powders generally, but especially that remarkable fluid, 
azotane, are examples in point. For mechanical purposes, 
a gradual production of gas is of course to be adopted. The 
evolution of carbonic acid gas, by the action of sulphuric 
acid on the carbonates, was an obvious case. On making 
the necessary calculations, this, with many other means, 
were found to be too expensive, because the scheme em¬ 
braced this principle—an expenditure of the gas. It was, 
therefore, with no little pleasure that I read the paper laid 
before the Royal Society, containing an account of the expe¬ 
riments made by Sir Humphry Davy 4 and Mr. Farraday, in 
which the condensation of the several gases into liquids was 
affected at a temperature, and under a pressure within prac¬ 
tical limits, proving thereby that some of those gases to 
which my attention had been directed on the principle of their 
expenditure, could be reproduced in the fluid form, and used 
again in the same way as alcohol and ether. It immedi¬ 
ately occurred to me, as a sine qua non condition of an 
engine working with such materials, that there be no mov¬ 
ing joint to which the gas can have access; in short, that 
there must not be a possibility of its escape, and that the 
simplest and most obvious means of satisfying this condition, 
was to make the same vessel alternately a boiler and a con¬ 
denser. Further consideration confirmed me in the idea of 
the practicability of this plan, since the difference of tempera¬ 
ture required to produce a great difference in the elastic 
force of the gas is but a few degrees when the minimum elas¬ 
ticity is already considerable. The project of an engine, as 
represented in the figure prefixed, was therefore substantially 
completed ; it remained only to adopt a mode of alternately 
heating and cooling the liquid employed. Several plans 
suggested themselves, but I prefer, for its simplicity, its cer¬ 
tainty, and the ease with which it can be regulated, the me¬ 
thod which will be immediately explained. 
“ Description of the Engine, jig. 3 .PL II. —The figure 
presents a vertical section ; with this remark, that as all the 
vessels have a circular form, an horizontal section becomes 
unnecessary. It is proper to observe, that the disposition of 
the parts as represented, has been adopted solely for the pur¬ 
pose of bringing the whole into one view. The engine con¬ 
sists of a duplication of parts, viz :— 
“ A A, two refrigerators, containing cold water. B B, ca- 
lorators, containing hot oil. C C, alternators lined with 
wood, and filled alternately with the hot and cold medium. 
D D, generators, consisting of a cylindrical assemblage of 
capillary copper tubes, about half filled, at the minimum 
pressure, with the carbonic acid, or other liquid employed— 
they communicate with the upper end of E E, strong copper 
gasometers, lined with wood, nearly full of oil, at the mini¬ 
mum elasticity of the gas, but which, at its maximum, expels 
nearly the whole of it into the H, cylinder, in which works 
I, the piston. L L, solid wooden plungers. M M, capil¬ 
lary glass tubes, for observing the movements of the oil, and 
fixed in a particular manner—they are not absolutely neces¬ 
sary. N N, pipes for a constant supply of cold water. 
O O, pipes through which gas is in the first introduced, and 
oil occasionally injected, in order to supply the waste at the 
piston rod—they are closed in a particular manner. O P, 
boards floating on the oil. S S, circular cisterns containing 
oil, each having a circular row of lamps; (-----), level of 
the water and of the oil; (.), level of the separation be¬ 
tween the water and the oil. 
“ Action of the Engine. —One of the gasometers being 
nearly full of oil, and the generator attached to it, with the 
7 C liquid 
