508 ON THE EXPLOSION OF THE BOILER 
weighs ;% of an ounce nearly. But, one ounce of 
water generates a cubic foot of steam, the elastic 
force of which is equal to the pressure of the 
atmosphere ; and, therefore, x of an ounce is the 
density of steam, the pressure of which is equal 
to that of the atmosphere. And, the density of 
steam is proportional to its pressure.—( LARDNER, 
on the Steam Engine, p. 321.) 
9. Given the cubic feet of steam, and its den- 
sity in the boiler, and the area of the aperture, in 
the boiler, through which the steam is discharged, 
it is required to find, in what time the pressure of 
the steam in the boiler, will become equal to that 
of the atmosphere, it being supposed, that the 
density of the steam, in every part of the boiler, 
at any given time, is the same as that, in the 
boiler, at the orifice, and that no steam is genera- 
ted during the time of its discharge, and that the 
steam moves, in the boiler, and issues at the ori- 
fice, in parallel plates. 
See »=the cubic feet of steam, in the boiler. 
D=the density of the steam, in the boiler, just before the 
discharge takes place. 
d= that of the steam, at the time ¢, in every part of the 
boiler : 
