224 COSMICAL ARRANGEMENTS. 



show," he says, " that I do not take gravity for 

 an essential property of bodies, I have added one 

 question concerning its cause, choosing to pro- 

 pose it by way of question, because I am not yet 

 satisfied about it for want of experiments." The 

 hypothesis which he thus suggests is, that there 

 is an elastic medium pervading all space, and 

 increasing in elasticity as we proceed from dense 

 bodies outwards : that this " causes the gravity 

 of such dense bodies to each other : every body 

 endeavouring to go from the denser parts of the 

 medium towards the rarer." Of this hypothesis 

 we may venture to say, that it is in the first 

 place quite gratuitous ; we cannot trace in any 

 other phenomena a medium possessing these 

 properties : and in the next place, that the hy- 

 pothesis contains several suppositions which are 

 more complex than the fact to be explained, and 

 none which are less so. Can we, on Newton's 

 principles, conceive an elastic medium otherwise 

 than as a collection of particles, repelling each 

 other? and is the repulsion of such particles a 

 simpler fact than the attraction of those which 

 gravitate ? And when we suppose that the me- 

 dium becomes more elastic as we proceed from 

 each attracting body, what cause can we conceive 

 capable of keeping it in such a condition, except 

 a repulsive force emanating from the body itself: 

 a supposition at least as much requiring to be 

 accounted for, as the attraction of the body. It 



