J 4 On Volcanos and Earthquakes, 



precise point is obtained, we shall find twenty-five thousand 

 six hundred feet, or about four miles and seven-eighths, equal 

 to the pressure of eight hundred atmospheres. 



Thence 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, if even 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- 

 ter ; on the contrary, it must descend to the bottom, with an 

 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. 



I request the reader to stop here, and reflect one moment ; 

 the novelty of the assertion, that a bubble of air is precipi- 

 tated to the bottom of the sea, instead of rising to its surface, 

 merits to be examined with attention before it is admitted ; 

 if it can be destroyed, either by argument or experiment, the 

 remainder of this article becomes useless, for all that follows 

 is in the form of corollaries from this first principle ; but if, 

 after a close and severe examination, the reader, as well as 

 myself, is convinced of its truth, let us then proceed together. 



If a series of bells, similar to the one just described, were 

 constantly in operation through the whole extent of the 

 ocean, there would soon be, under the water of the sea, a 

 layer of compressed air of its whole extent. But has nature 

 provided for such an apparatus ? Yes, she has, with the sim- 

 plicity, ease, grandeur, and efficacy that she shows in all 

 her operations ; let us merely study her laws, and we shall 

 soon discover it. 



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 observe 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- 

 bles before the moment of ebullition ; and, still better, let us 

 put some of it into a glass under the receiver of an air-pump, 

 and produce a vacuum, when the bubbles will rise with 



