STEAM ENGINE. 
at the same time with the cylinder, leading 
from the top of it, and by a crooked passage 
to the cock, E j g- g- is another similar 
passage from the bottom of the cylinder 
(wiiici is closed except this pipe has an iron 
bottom screwed to it) to the cock, and 
enters the cock diametrically opposite to the 
other passage ; A is a passage bringing 
steam from < he jacket, ccc ; by means of a 
short pipe not seen in the figure, being be- 
hind the cylinder, cast at the same time 
with the cylinder, and joining at the bottom 
to the flanclr, by vrliich the cylinder is 
screwed into the jacket, ccc; the bore of 
this short pipe is however contimm-d 
through the tlanch, and opens into the 
jacket, and when they are screwed toge- 
ther the steam has then free access from tlie 
boiler tlnongh t’ue jacket into the short 
pipe, and from tlieace into the passage, h, 
which goes horizontal towards it ; the short 
pipe lies a tliin circular vane in it, turning 
on a pivot ac'oss the centre of it, which 
comes through the pipe, and ligs a handle on 
it ; by turning this handle tiie spindle and 
vane are turned also ; when tiie vane is set, 
so that its plane is perpendicular to the 
axis of the pipe, it neai iy fills the c'rcu’ar 
passage, and allows very little steam to 
pass by it ; but when the vane is turned 
edgeways, it presents very little smtace, 
and the steam passes by without obstruc- 
tion to the cock, E ; ppp is a pipe convey- 
ing the steam away from the engine, to the 
condenser, which is an iron cylinder, F F, 
immersed in cold water, contained in a cast 
iron cistern, GG; the condenser, FF, has a 
passage from tlie bottom of it, leading to a 
pump, H H, called the air-pump, and in 
■which is a valve, i, shutting towards tlie 
condenser, and preventing any passage 
from the air-pump to the condenser, though 
the valve will easily open and allow a 
passage the other way. The air-pump has 
a bucket, k, sliding up and down in it ; the 
bucket has a hole through it, covered by a 
valve, I, wliicli opens upwards, and pre- 
vents the descent of 'any fluid which may 
be above it ; I is a square iron cistern 
screwed on the top of the air-pump, it has 
a stnfiing box in the bottom over the centre 
of the pump, through which the bucket rod 
of the air-pump moves freely, yet perfectly 
air-tight ; the bottom of the cistern, I, has 
also two valves, m m, in it, over the air- 
pump ; K is a handle fixed upon a spindle, 
on which is a rack turning a cog-wheel 
upon the end of the cook, E ; this rack and 
wheel is taken away in the section, hut is 
plainly seen in Plate 7!. ; L M are two pins 
fixed upon tiie rod of the aii-pump, and 
taking the handle, K, as they move up and 
down, and thus turning the cock, E ; n n is 
a lever fixed on the spindle of the handle, K, 
its ends stop against the ends of a crooked 
iron, which is screwed to the iron frame, 
supporting the bearings for tlie spindle of 
the rack, so that the motion allowed 
thereby to the handle, K, and fue rack, will 
turn the cock c:ie-fourth of a whole turn, 
hut no more ; N is a cock communicating 
(when open) from the jacket, c c, to the 
pipe, pn, and thereby to tire condenser. 
The condenser, F F, has a pipe entering 
it, and turnerj up within it, the pipe opens 
to the water in its condensing cistern, G G, 
and has a cock in its outer end which regu- 
lates the quantity of water the pipe will ad- 
mit, or closes it entirely ; the cock has a 
long handle coming up out of the water, 
which is not seen in the section ; but is de- 
noted by 0 , in Plate I. 
Suppose every thing in the position of the 
Section, the operation of tiie engine is as 
follows : when the water, in the boiler A, 
P.ate I. is heated by the fire made under it 
at X, the heat which enters into combina- 
tion with the water, causes it to expand and 
form steam ; in this state it raises and fills 
the boiler, and thence through the pipe, e, 
enters between the jacket, c c, and the cy- 
linder; before the engine can be worked, 
the steam must be heated, until it is ex- 
panded so much, that it will rush forcibly 
out of the boiler when permitted. The 
steam also passes through the short pipe be. 
fore described, into the passage, h, and 
thence, through the crooked passage in the 
cock, F, to the pipe, gg, and the bottom of 
the cylinder, though it will not enter the 
cylinder, because it is yet filled with air. 
The person who attends the engine must 
now open the cock, N, this admits the 
steam from the boiler into the condenser ; 
it rushes violently through the pipe,pp, into 
the condenser, F F, driving the air it con- 
tained through the three valves, i, I, and )w, 
which it opens, into the cistern, I, (where it 
is open to the atmosphere, the lid of that 
cistern being only laid on, and not fit- 
ting tight) this operation (called blowing 
through) continued for a few seconds, ex- 
pels all the air from the condenser, and fills 
it with liot steam; the cock, N, is now 
closed, and the injection cock, of which O, 
Plate I. is the handle, is opened ; this 
allows a small stream of cold water, from 
the cistern, G, to enter into the condenser. 
