[ 539 '] • 
the quantity of elaftic vapour raifed might be con- 
fiderably encreafed, and lefs fuel and a lefs boiler 
might then ferve the purpofe. The wheel might 
be turned round by the water drawn up by the en- 
gine ; or might receive its motion from the beam of 
the engine by means of a crank; or a labourer might 
be employed in turning it round with the hand. See 
Tab. XVI. Fig. i. 
But the defired effedt might, in all probability, be 
better produced by means of elaftic fteam driven 
brifkly through the boiling water. The fteam of 
water, as an elaftic fluid, pofteftes many of the pro- 
perties of common air. 
Like air, when driven brifkly from the aeolipile, 
it is obferved to blow up fire ; and when forcibly 
driven through water, will doubtlefs produce the 
the fame agitation therein, as is done by common 
air in Dr. Hales’s experiment ; and may probably 
have the like effedt with air, in elevating a larger 
quantity of elaftic vapours. 
In order to excite an agitation in the boiling wa- 
ter of a fire-engine, by means of elaftic fteam, the 
following fimple and eafy method may be tried. 
Fig. II. 
a acta* The boiler of the fire-engine. 
b. An aeolipile, or fmaller boiler, annexed to the 
larger, receiving boiling water from it by the 
pipe (c\ and continually emptying ftrongly 
elaftic fteam into it, by the alembic and tube 
idd ) ; which tube towards the bottom of the 
boiler is divided into many fmaller tubes (fff\ 
per- 
