THE EARTH. 155 



came irresistible. The bursting of rocks, by 

 frost, which is frequent in the northern climates, 

 and is sometimes seen in our own, is an equal 

 proof of the expansion of congealed water ; for 

 having, by some means, insinuated itself into the 

 body of the rock, it has remained there till the 

 cold was sufficient to affect it by congelation. 

 But when once frozen, no obstacle is able to con- 

 fine it from dilating ; and if it cannot otherwise 

 find room, the rock must burst asunder. 



This alteration in the bulk of water might 

 have served as a proof that it was capable of 

 being compressed into a narrower space than it 

 occupied before ; but, till of late, water was held 

 to be incompressible. The general opinion was, 

 that no art whatsoever could squeeze it into a 

 narrower compass ; that no power on earth, for 

 instance, could force a pint of water into a vessel 

 that held a hair's-breadth less than a pint. And 

 this, said they, appears from the famous Floren- 

 tine experiment ; where the water, rather than 

 suffer compressure, was seen to ooze through the 

 pores of the solid metal, and at length, making a 

 cleft in the side, spun out with great vehemence. 

 But later trials have proved that water is very 

 compressible, and partakes of that elasticity which 

 every other body possesses in some degree. In- 

 deed, had not mankind been dazzled by the bril- 

 liancy of one inconclusive experiment, there were 

 numerous reasons to convince them of its having 

 the same properties with other substances. Ice, 

 which is water in another state, is very elastic. A 

 stone flung slantingly along the surface of a pond, 



