SECOND LAW OF GRAVITATION. 103 



tation; but it is gravitation which we cannot 

 measure in the primary particle ; and therefore it 

 would be vain for us to inquire, or seek to be in- 

 formed of what gravitation is, because we have 

 pursued our analysis to its very beginning, and 

 there we equally speak truth when we say "gravita- 

 tion is matter," and " matter is gravitation ;" for to 

 our perception they are one and the same. 



The second law of gravitation, which it is ne- 

 cessary for every useful observer of nature to know 

 and to bear in mind, is the law of its variation. 

 That law is no variation in the quantity of gravita- 

 tion itself, because, being the primary quality of mat- 

 ter, gravitation is as indestructible, either in whole 

 or in part, as matter itself, and can be destroyed 

 only by the same power that made it. When we 

 divide matter, we divide gravitation along with it ; 

 but there is no ingenuity in man, and we know of 

 no process in nature, by which any one portion of 

 material substance can be deprived of the least 

 shade of its material quantity. The little particle 

 of water, while it is rising in vapour through the 

 dry air, so fine that no eye or instrument can 

 recognize its existence, has the quality of gravita- 

 tion as perfect as if it were dashing down the 

 rocks in the mighty flood at Niagara; and the 

 smoke which ascends upward in the free air, would, 

 in a vessel from which the air had been all pumped 

 out, lie at the bottom the same as a stone. The 

 cork that floats on the surface of water has the very 

 same gravitation, in proportion to its quantity of 

 matter, as the lead which sinks to the bottom. 

 The absolute gravity of any one substance is ex- 

 actly the same as that of any other ; and the only 

 variations are, there being less or more of the sub-. 



