264 



Mr. MacKain on the Compression of Water, 



I shall now proceed to compare the rates of compression under this 

 theory, with those indicated by experiment. 



Air is found to be compressed into one half its bulk by the addi- 

 tion of a weight equal to that of the atmosphere, or the addition of a 

 force equal to 28*330 feet of air. In the same proportions between gas 

 and water indicated by the impelling and retarding forces in a long 

 train of pipes, water should also be compressed into one half its bulk, 

 by the addition of a force equivalent to a column of itself, 28*330 feet 

 or 5*36 miles. 



Professor Leslie estimates that it will be only compressed to this 

 degree, at the depth of 93 miles. 



It has already been mentioned that Mr. Canton had indications 

 which represented the contraction of pure water as 46 million parts, 

 and sea water as 40 million parts, by the addition of a force equal to 

 the weight of the atmosphere. By the rule of compression followed 

 in this paper, pure water would compress 11-65 millionth parts — and sea 

 water 11*55 parts in a million, with the pressure due to an atmosphere 

 of air. 



Zimmerman arrived at the conclusion that sea water compresses 

 ■^\^ part, when under the pressure of 1000 feet of its own body,^ — the 

 present theory indicates that it would contract very nearly ^-^ parts 

 under the same pressure. 



Professor (Ersted's apparatus, judging from the engraving in the 

 transactions of the British Association, seems to have been incapable 

 of measuring with accuracy the forces stated to have been used. 



In 1826 Mr. Perkins laid before the Royal Society, a table of com- 

 pression of water, derived from experiment, in which he states that of 

 a column of 190 inches of water to have been for 



Parts. 



0176 

 1*385 

 2*395 

 5*010 

 6*961 

 8-855 



while by the theory now advanced these compressions would have 

 been 



Parts. 



2-1 

 20*0 

 36*2 

 70*4 

 89-1 

 102*7 



