§24- 
Mr. Boswell suggests, as a considerable 
improvement, that the action of this engine 
should he made elastic by the addition of an 
air-chamber, on the same principle as that 
used in fire-engines: tiiis, he thinks, might 
■lie best effected by making the piston hollow, 
with a small orilice in the bottom, and of a 
larger size, to serve for this purpose, as the 
spring of the air would then act both on the 
upward and downward pressure of the water. 
En gin e, steam. The steam-engine is one 
•®f the noblest monuments of human inge- 
nuity. It was originally invented by the 
marquis of Worcester, in the reign of Charles 
II. This nobleman, who appears to have 
-been possessed of much knowledge, with a 
fertile imagination, published in 1663, a small 
book, called “ A Century of Inventions,” 
giving an account of a hundred discoveries 
or contrivances of his own ; but the descrip- 
tions of many of them are altogether unin- 
telligible. 
Among them is an account of his invention 
of raising water by the force of steam, which, i 
•now that we are possessed of the engine, ap- 
pears to agree very well with its construction. 
Tut-as there is no plate to accompany his de- 
scription, we are entirely unacquainted with 
the particular mode in which he applied the 
power of steam. It does not appear, how- 
ever, that he met with sufficient encourage- 
ment ; and this useful discovery was long 
neglected. 
Towards the end of the century, captain 
Savary, a person of great ingenuity, having 
robably seen the account of the marquis of 
Worcester’s invention, was convinced of its 
practicability, and succeeded in constructing 
a machine of this kind. He obtained a pa- 
tent for the invention, and erected several 
steam-engines, which he described in a book 
entitled “ The Miner’s Friend,” published 
in 1696. 
The following is the description of his ma- 
chine, as improved by himself: 
A (Plate fig. 1) is a strong boiler, built 
in a furnace lor generating steam. From 
the top of this boiler there proceeds a pipe, 
A), which conveys the steam into another 
strong vessel, r, called the receiver. This 
f 'ipe lias a cock at c, called the steam-cock. 
n the bottom of the receiver is a pipe S, 
which communicates with the rising-pipe 
H n k, the lower end of which is immersed 
in the well from which the water is to be 
raised. Immediately below the place where 
the pipe S enters the rising-pipe, there is a 
valve, n, opening upwards. A similar valve 
is also placed at i, above the pipe S. Lastly, 
ithere h a pipe e, which branching off from 
the rising-pipe, enters the top of the receiver. 
This pipe has also a cock, d, called the in- 
jection-cock. The mouth of the pipe e, has 
on the end f a nozzle, pierced lull of holes, 
..pointing from a centre in every direction. 
The keys of the two cocks c and d, are united 
fey the handle h, called the regulator. 
The mode of operation is as follows : Let 
the regulator be so placed, that. the steam- 
cock c be open, and the injection-cock d 
shut: put water into the boiler A, and make 
it boil. The steam from it will enter the 
pipe b, and fill the receiver, first driving out 
the air which it before contained ; a consider- 
able quantity of steam will be at first con- 
densed by the cold sides of the receiver ; 
but it being at length warmed, the steam will 
ENGINES. 
proceed into the rising-pipe, lifting up the 
valve i. When this is perceived to lie the 
case, by the rising-pipe feeling warm, and 
hearing the valve i rattle, the communication 
is now to be cut from the boiler, by shutting 
the steam-cork c, the injection cock d being 
also shut. 1 he receiver now gradually cools, 
and the steam included in it condenses into 
water. When this is the case, as the air was 
at first driven out by the steam, and cannot 
return again, all the cocks being shut, a 
vacuum is formed in the receiver ; conse- 
quently, there is nothing to counterbalance 
the pressure of the atmosphere, which acting 
upon the water in the well, forces it up the 
rising-pipe, and fills the receiver. 11 le 
steam-cock is now opened; and the steam 
from the boiler rushing in with great vio- 
lence, presses upon the surface of the water 
in the receiver, and forcing it through the 
pipe s, into the rising-pipe, causes it to shut 
the valve n, and open the other valve i; 
and, provided the steam be sufficiently strong, 
t will force it up the rising-pipe to the top k, 
where it is delivered. The cock c is kept 
open until all the water be driven out of the 
receiver, and it is again filled with steam. 
The regulator is now applied, which shuts 
the steam-cock, whilst at the same time it 
opens the injection-cock. The rising-pipe 
being still full of water, a stream of cold 
water proceeds through the pipe e, and en- 
ters the receiver in a shower. This instantly 
condenses the steam in the receiver, and pro- 
duces a vacuum as before ; in consequence 
of which, the water from the well is again 
forced up by the external pressure of the 
atmosphere, and the receiver is again filled 
with water. The regulator is then turned, 
which shuts the injection-cock and opens the 
steam-cock, which permits the steam from 
the boiler to press upon the water, and again 
force it up the rising-pipe. This operation 
filling the receiver with water by means of 
a vacuum produced in it, and forcing it up 
the rising-pipe by the pressure of the steam 
from the boiler, is constantly repeated, by 
merely turning the regulator, which shuts 
and opens the steam-cocks and injection- 
cocks alternately. 
This construction of the steam-engine is 
extremely simple, and might perhaps be suc- 
cessfully’applied for some purposes. But it 
has several considerable defects. It may 
readily be apprehended, that the action of 
the direct steam on any definite surface 
(such, for example, as a square inch) will be 
accurately equal to the re-action of the water 
which is forced up ; and consequently, that 
Savary’s engine will require steam more 
elastic than the air of the atmosphere, in 
every case except where the water is raised 
no higher than it can be by the vacuum that 
is produced, and the pressure of the atmo- 
sphere. When the water is forced \qa through 
the rising-pipe, every square inch of the 
boiler must sustain a pressure equal to a co- 
lumn of water an inch square, and of the 
height of the pipe above the boiler. This, 
therefore, requires very strong vessels, and 
several accidents happen by their bursting 
when the safety valve is loaded too much. 
But the greatest defect of this machine is 
the great waste of steam, and consequently 
of fuel. For when the steam is admitted to 
the top of the cold water in the receiver, it 
is condensed with great rapidity ; and the 
water does not begin to yield to its pressure, 
until its surface is so hot, as not to condense 
any more steam : it now descends ; but as by 
that, a new part of the side of the receiver ii 
exposed to the steam, more is condensed, 
so that a condensation of the steam is going 
on all the while the water is descending. 
This too must necessarily be repeated every 
stroke, as the receiver is cooled every time 
it is filled with water. 
Mr. Savary succeeded in raising water to 
smali heights, and erected several engines in 
different parts of England; but he could 
make nothing of deep mines. Many at- 
tempts have been made to correct these de- 
fects, but hitherto without much success. 
In the beginning of the eighteenth cen- 
tury, Newcomen, an ironmonger or smith, 
and Crauly, a glazier at Dartmouth, in De- 
vonshire, first conceived the project ot ap- 
plying a piston with a lever, and other ma- 
chinery. They were contented to share the 
profits of the invention with Savary, who 
procured a patent for it in 1705, in which 
they were all three joined. 
Fig. 2, exhibits a section of Newcomen’s 
engine: a is the boiler, built in brick-work. 
In the top of the boiler is a steam-pipe, c, 
communicating with the cylinder, b, which 
is of metal, and is bored very truly. r I he 
lower aperture of this pipe is shut by the 
plate n, which is ground very fiat, so as to 
apply very accurately to the whole circum- 
ference of the orifice. This plate is called 
the regulator, or steam-cock, and it turns 
horizontally round an axis o, which passes 
through the top of the boiler, and is fitted 
by grinding to the socket, so as to be steam- 
tight. It is opened and shut by a handle 
fixed to its axis. 
In the cylinder b is a solid piston, p, well 
fitted into it, and made air-tight by a pack- 
ing of leather or soft rope, well filled with 
tallow ; and for greater security, a small 
quantity of water is kept above the piston. 
The piston-rod d is suspended by a chain, 
which is fixed to the upper extremity of the 
arched head e of the great lever, or working- 
beam, e f g, which turns on the gudgeon t. 
There is a similar arched head g, at the other 
end of the beam ; to the upper extremity of 
which is fixed a chain, carrying the pump- 
rod h, which raises the water from the mine. 
The load on this end of the beam is made 
to exceed considerably the weight of the 
piston at the other extremity. 
At a small height above the top of the cy- 
linder, is a cistern called the injection-cis- 
terlvi- From this descends the injection- 
pipe, k, which enters the bottom of the cy- 
linder, an<J terminates in a nozzle pierced 
with holes. This pipe has a cock, 1, called 
the injection-cock. 
At the opposite side of the cylinder, a little 
above its bottom, there is a lateral pipe m, 
turning upwards at the extremity; and there 
covered by a clack-valve, called the snifting- 
valve, which has a little dish round it, to hold 
water for keeping it air-tight. 
There proceeds also from the bottom o 
the cylinder, a pipe g, of which the lower 
end is turned upwards, and is covered with 
a valve r. This part is immersed in a cis- 
tern of water, called the hot-well, and the 
pipe itself is called the eduction-pipe 
Lastly, the boiler is furnished with a safe ty 
valve, called the puppet-clack, in the same 
