[ 543 ] 
To the head of the boiler let a pipe of call iron be 
fitted nearly in an horizontal pofition, as in Fig. 3.. 
but inclining a little towards the boiler- and let this 
pipe be continually kept red hot, by the fire of an 
air-furnace, through which it may pafs ; and thro’ 
this pipe let the watry fleam be conducted to the 
cylinder of the fire-engine. 
Or the fleam may be rarined by making it pafs 
from the boiler to the cylinder, through an iron pipe 
or cylinder fixed in the flue of the furnace, of which 
contrivance a rude fketch is given in Fig. 4,. 
N. B. The evaporation from the boiler may perhaps 
be confiderably quickened by the rarefaction of 
the fleam. 
It may not be improper to make trial of one or 
both of the above methods of heating the fleam, or 
of other methods, that are more commodious ; and 
alfo to add to the boiler the above recommended 
apparatus for raifing a larger quantity of fleam, by 
means of mechanical agitation. The fire-engine, as 
fir ft invented by Savery, w^as rude and imperfeCt 
and fince his time many ingenious men have been 
continually making improvements therein ; neither 
doth it yet feem to have attained to its greateft de- 
gree of perfeClion. There is even reafon to hope 
that, by one or both of the methods here pointed 
out, viz. (either by encreafing the quantity of fleam, 
or by augmenting its force) it may be brought to 
work with much fmaller boilers, and with a very 
moderate expence of fuel j and under fuch circum- 
ilances it might be applied to a vaft variety of pur- 
poles, and vrould become of much greater ufe to 
mankind. 
Z z z 2 
LXXVI. 
