[ 54 ] 
would be fufficlently flrong for the purpofe of the 
fleam-engine. 
I made an experiment firfl on a fmall boiler, 
about 1 2 inches diameter, made in the fhape of thofe 
commonly ufed in fleam-engines, with a funnel at 
the top, of about i inch diameter, for the fleam to 
pafs thro’ ; the aperture of which was covered with 
a thin plate, fixt at one end with a hinge, and a 
fmall leaden weight to Hide on the other, in the na- 
ture of a fleel-yard, to mark the flrength or quantity 
of the fleam. A tin pipe made for this purpofe, 
with feveral fmall holes towards the end, paffed 
from a fmall pair of bellows, through the upper 
part of the boiler, to within about an inch of the 
bottom. The boiler was half filled with water, 
which covered the holes in the pipe about fix inches. 
From the befl obfervation I was capable of making 
with this machine, by blowing air thro’ the boiling 
water, it produced about £ more fleam than was 
produced by the fame fire without blowing air 
thro’. 
I then applied a machine of this kind to the en- 
gine at the York-buildings water- works, the boiler 
of which is 15 feet diameter. This is a patent- 
boiler, a fe< 5 lion and plan of which is annexed. It 
has a double concave, with a kind of door-way or 
paffage from one to the other, in order to let the 
flame pafs, as it were, thro’ and round the water j by 
which means there is no-where above nine inches of 
water to be heated thro’, tho’ the boiler is fo large ; 
and which, by three years experience, has been 
found to require | lefs fuel, than any other fire-en- 
gine of equal bignefs. 
I fixt 
