90 On a New T7ieoty of the Tides. 



water is : and in proportion to its depth will be the degree of 

 its expansion. 



The compressibility of water to a certain extent has been 

 proved by Mr. Perkins, and is now, I understand, admitted by 

 all the philosophers. The only question then is, "Whether it 

 be compressible in a sufficient degree to produce the effects 

 I have sujiposed. And, as no one can pretend to set bounds 

 to the extreme depth of the ocean, or say to what degree wa- 

 ter may be compressed in its deepest parts, no one can say 

 that my hypothesis is impossible, or even improbable ; while 

 every one who is capable of thinking, when he considers that 

 the moon's attraction has no power to lift the smallest or 

 lightest substance that happens to be loose upon the surface of 

 the earth, nuist be convinced that it could have no power to 

 raise water, if it was not aided by some other principle; and 

 surely there is no other principle that can aid in producing 

 tliis effect, besides the elasticity of the particles of water. 



Mr. Perkuis, by a force which he considered equal to the 

 weight of 320 atmospheres, or about two miles depth of water, 

 compressed the water in a piezometer at the rate of three and 

 a half per cent. In what manner the experiment was con- 

 trived 1 do not pretend to know ; but, when we consider that 

 ■water, in another experiment of his, forced its way into a bot- 

 tle that was corked and sealed, it is certainly very possible that 

 some of these minute particles might have escaped from the 

 instrument before it was weighed, and thus the degree of com- 

 pressibility may have been considerably underrated. This 

 appears to me to be the more likely, because in another of 

 Mr. Perkins's experiments the degree of compression was evi- 

 dently a great deal more. In this experiment, the water, 

 which had forced its way through the sealing of an empty 

 porter bottle, at the depth of five hundred fathoms, on being 

 draAvn u}) and the external pressure in great measure di- 

 minished, expanded to such a degree that it forced the cork 

 up against the coverings, compressed it into half its size, and 

 then burst the bottle. As we have no means of measuring 

 the degree of compression in tliis experiment, we must content 

 ourselves with a rough estimate ; but it is evident that it must 

 have been equal to the space that was occupied by the cork 

 before it was forced up, because the bottle burst afterwards ; 

 and this, nt the lowest calculation, could not have been less 

 tlian three })er cent, when the force applied was very little 

 more than the weight of one hundred atmospheres. A quart 

 bottle is generally supposed to hold about a dozen common- 

 sized wine-glasses ; and if we suppose the space that was oc^ 

 cupied by that part of tlie cork that was forced upwards to be 

 . ' ,the 



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