Energy and Ether. 1021 



with a windlass or some other mechanical contrivance, it will hold it up, 

 but will fail to hold any more, and when that which it thus holds up is 

 pulled away from it, there will be restored to it as much force as was 

 required to pull away the weight. 



Now in looking among these phenomena of electrical energy, it is 

 not difficult to discover those which are comparable with the phenomena 

 of gravitation. Gravitation is like magnetism in the fact that its at- 

 tractive force alwa}*s overpowers its repulsive force. But compared 

 with magnetism it is effective at an infinitely longer range, while mag- 

 netism is of vastly greater force at short range. The rapidity of elec- 

 trical induction is practically the same as that of light, and probably 

 the propagation of the influence of gravity is the same; but we have no 

 means of making gravity cease and begin, as we have in the case of 

 electrical phenomena, and so we never can find out how fast its influence 

 travels. At any rate, however, no planet or sun has yet been found to 

 travel fast enough to get away from its influence. 



Now if we conceive every atom of ponderable matter to be a perma- 

 nent magnet endowed with a power of attraction similar to that of mag- 

 netism, and with a power of induction like that of electricity, we have 

 the substantial conditions of gravitation, and it becomes a sort of cross 

 between magnetism and electricity. We have already attributed the 

 phenomena of electricity and magnetism to movements imposed upon 

 an imponderable ether, the same substance to whose movements in a 

 different way, are attributed the phenomena of light and heat. In sup- 

 posing gravity to be another form of motion of ether, we must con- 

 ceive it as being the earliest and most elementary form. By means of 

 heat we can destroy the magnetism of a steel magnet and it is not re- 

 stored by simply being cooled off. But gravity cannot be annihilated 

 by any means at our command. The force of gravity may be less or 

 more, according to the distances apart of the attracting atoms, but it 

 always remains and becomes appreciable when the distance is sufficiently 

 reduced. We perceive then, that while as forms of motion, magnetism, 

 electricity, heat, light, nervous action, &c. , are in some degree equiva- 

 lents of each other, and can be exchanged for each other, one entirely 

 disappearing often in giving rise to another, gravity is subject to no 

 such accident. When a body becomes magnetic or electric it does not 

 lose its gravity. So that while the force of gravity comes and goes, 

 the property never does. Compare this fact again with magnetism. 

 The magnetic particle may not lose its property of attraction for a long 

 time, although its force varies under the same conditions that affect the 

 ponderable particle. Thus while gravity becomes a mode of energy 

 quite as intelligible to us as magnetism, and presenting many parallels 

 with it, its endowment appears to be perpetual instead of temporary 

 like that of the magnet. 



