14 On Volcanos and Earthquakes. 
precise point is obtained, we shall find twenty-five thousiand 
six hundred feet, or about four miles and seven-eighths, equal 
to the pressure of eight hundred atmospheres. 
ence it follows, that at the depth of four miles and sev- 
en-eighths the air would be compressed in the bell to the 
same density with the sea water. 
But now, when arrived at this point, if we plunge the bell 
more and more into the sea, the density will still-increase, 
and will soon exceed that of the surrounding water ; at that 
moment what will become of the bubble of air contained in 
the bell,ifeven we suppose it to be upset? 
Will it come up and break at the surface? It cannot, for 
by the supposition, it is heavier than its own volume of wa- 
2: m .- 8 kL i. + es to _. a net ; an 
ter ; on t 
increased 
. a ee . . . j 3% - 
increased velocity ; for its density will increase as it sinks, 
and it must remain at the bottom of the sea, just as a stone 
itself would do. 
soon discover 
Let us take a glass of water from a running spring ; let us 
expose it for some time to the light and heat of the sun; we 
shall soon c ve bubbles rising from every part of the wa- 
ter, collecting at the surface, and breaking the one after the 
other. Let us put some of the same water into a convenient 
vessel by the fire, and we shall again observe a rising of bub- 
poo ry pee et and, still better, let us 
Some of it into a glass under the receiver of an air-pump, 
and produce a vacuum, when the bubbles will rise with 
aera it mates oie Sh Sk athe 
Pee . 
