M ECH 
when p re fled from below, and fh lifting when prefled down¬ 
wards. A fimilar valve is placed at I, immediately above 
the pipe of communication. Laltiy, there is a pipe E D, 
which branches off from the riling-pipe, and enters in¬ 
to the top of the receiver. This pipe has a cock D, 
called the injection cock. The mouth of the pipe ED has 
a nozzle f pierced with fmall holes, pointing from a centre 
in every direction. The keys of the two cocks C and D 
are united, and the handle gk is called the regulator. 
Let the regulator be fo placed, that the fleam-cock C 
is open, and the injectioq-cock D is fhut; put water into 
the boiler A, and make it boil ftrongly. The fleam 
coming from it will enter the receiver, and gradually 
warm it, much fleam being condenfed in producing this 
effeft. When it has been warmed fo as to condenfe no 
more, the fleam proceeds into the rifing-pipe; the valve 
G remains fliut by its weight; the fleam lifts the valve I, 
and gets into the rifing-pipe, and gradually warms it. 
When the workman feels this to be the cafe, or hears the 
rattling of the valve I, he immediately turns the fleam- 
cock fo as to fliut it, the injeftion-cock ftill remaining 
fhut'; (at leaft we may fuppofe this for the prefent.) The 
apparatus muft now cool, and the fleam in the receiver 
collapfes into water. There is nothing now to balance 
the preffure of the atmofphere; the valve I remains fliut 
by its weight; but the air incumbent on the water in the 
pit preffes up this water through the fuftion-pipe HG, 
and caufes it to lift the valve G, and flow into the receiver 
R, and fill it to the top, if not more than 20 or 25 feet 
above the furface of the pit-water. 
The fleam-cock is now opened. The fleam which, 
during the cooling of the receiver, has been accumulating 
in the boiler, and acquiring a great elafficity by the aftion 
of the fire, now ruffles in with great violence, and, prefling 
on the furface of the water in the receiver, caufes it to 
fhut the valve G and open the valve I by its weight alone, 
and it now flows into the rifing-pipe, and would Hand on 
a level if the elafficity of the fteatn were no more than 
what would balance the atmofpherical preffure. But it is 
more than this, and therefore it prejfet the water out of 
the receiver into the rifing-pipe, and will even eaufe it 
to come out at K, if the elafficity of the fleam is fuffi- 
ciently great. In order to enfure this, the boiler has ano¬ 
ther pipe in its top, covered with a fajety valve V, which 
is kept down by a weight W fufpended on a fteelyard 
LM. This weight is fo adjufted, that its preffure on the 
fafety-valve is fomewhat greater than the preffure of a 
column of water Vi as high as the point of difeharge K. 
The fire is (o regulated, that the fleam is always iifuing 
a little by the loaded valve V. The workman keeps the 
fleam-valve open till he hears the valve I rattle. This 
fells him that the water is all forced out of the receiver, 
and that the fleam is now following it. He immediately 
turns the regulator which (huts the fleam-cock, and now, 
for the firft time, opens the injeftion-cock. The cold 
water trickles at firft through the holes' of the nozzle f, 
and, falling down through the fleam, begins to condenle 
it; and then, its elafficity being lefs than the preffure of 
the water in the pipe KE B/, the cold water fpouts in all 
directions through the nozzle, and, quick as thought, 
produces a complete condenfation. The valve G now 
•opens again by the preffure of the atmofphere on the wa¬ 
ter of the pit, and the receiver is foon filled with cold 
water. The injeftion-cock is then fliut, and the (team- 
cock opened, and the whole operation is now repeated ; 
and fo on continually. 
This is the Ample account of the procefs, and will ferve 
to give the reader an introductory notion of the operation ; 
but a more minute attention muft be paid to many parti¬ 
culars before we can fee the properties and defects of this 
ingenious machine. The water is driven along the rifing- 
pipe by the elafficity of the fleam. This muft, in the 
boiler and in every part of the machine, exert a preffure 
on every fquare inch of the veffels, equal to that cf?the 
upright column of water. Suppofe the water to be raifed 
A N I G 3 . 771 
100 feet, about 25 of this may be done in the fuftion-pipe ; 
that is, the upper part of the receiver may be about 25 
feet above,the furface of the pit-water. The remaining 
75 muft be done by forcing; and every fquare inch of the 
boiler will be fqueezed out by a preffure of more than 
thirty pounds. This very moderate height therefore re¬ 
quires very ft-rong veffels; and the marquis of Worcefter 
was well aware of the danger of their burlting. A copper 
boiler of fix feet diameter muft be nine-tenths of an inch 
thick to be juft; in equilibrio with this preffure: and the 
foldered joint will not be able to withftand it, efpecially 
in the high temperature to which the water muft be heated 
in order to produce fleam of fufficient elalticity. This 
temperature muft be at leaft 280° of Fahrenheit’s ther¬ 
mometer. In this heat, foft folder is juft ready to melt, 
and has no tenacity; even fpelter-folder is confiderably 
weakened by it. Accordingly, in a machine erected by 
Dr. Defaguliers, the workman having loaded the fafety- 
valve a little more than ufual to make tile engine work 
more brifkly, the boiler burft with a dreadful explofion, 
and blew up the furnace and adjoining parts of the build¬ 
ing. Mr. Savery fucceeded pretty well in railing mode¬ 
rate quantities of water to fmall heights, but could.make 
nothing of deep mines. Many attempts were made, on 
the marquis’s principle, to flrengthen tile veffels from 
within by radiated bars and by hoops, but in vain. Very 
fmall boilers or evaporators were then tried, kept red-hor, 
or nearly fo, and fupplied with a (lender ftream of water 
trickling into them ; but this afforded no oppoitunity of 
making a collection of fleam during the refrigeration of 
the receiver, fo as to have a magazine of fleam, in readi- 
nefs for the next forcing-operation ; and the working of 
fuch machines was always an employment of great danger 
and anxiety. 
The only fituation in which this machine could be 
employed with perfect fafety, and with lbme effeft, was 
where the whole lift did not exceed 30 or 35 feet. In 
this cafe the greatejl part of it was performed by the 
fuftion-pipe, and a very manageable preffure was fufficient 
for the reft. Several machines of this kind were erefted in 
England about the beginning of the lalt century. A very 
large one was erefted at a fait-w^rk in the fouth of France. 
Here the water was to be raifed no more than 18 feet. The 
receiver was capacious, and it was occafionally fupplied 
with fleam from a fmall lalt-pan conftruCted on purpofe 
with a cover. The entry of the /team into the receiver 
merely allowed the water to run out of it by a large valve, 
which was opened by the hand ; and the condenfation was 
produced by the helpof a fmall forcing-pump, alfo worked 
by the hand. In fo particular a fituation as this, (and 
many fuch may occur in the endlefs variety of human 
wants,) this is a very powerful engine; and, having few 
moving and rubbing parts, it muft be of great durability. 
An ingenious attempt was made very lately to adapt this 
conftruftion to the ules of the miners. The whole depth 
of the pit was divided into lifts of 15 feet, in the fame 
manner as is frequently done in pump-machines. In each 
of thefe was a fuftion-pipe fourteen feet long, having 
above it a fmall receiver like R in the preceding figure, 
about a foot high, and its capacity fomewhat greater than 
that of the pipe. This receiver had a valve at the head 
of the fuftion-pipe, and another opening outwards into 
the little cittern, into which the next fuftion-pipe above 
dipped to take in water. Each of thefe receivers fent up 
a pipe from its top, which all met in the cover of a large 
veffel above ground, which was of double the capacity of 
all the receivers and pipes. This veffel was clofe on all 
Tides. Another veffel, of equal capacity, was placed im¬ 
mediately above it, with a pipe from its bottom palling 
through the cover of the lower veffel and reaching near 
to its bottom. This upper veffel communicates with the 
boiler, and conftitutes the receiver of the fleam-engine. 
The operation is as follows : The lower veffel is full of 
water. Steam is admitted into the upper veffel, which 
expels the air by a valve, and fills the veflel. It is then 
. condenled 
