SCIENCE. 



[N. S. Vol. XII. No. 310. 



Electrically charged bodies are of two kinds, 

 namely, positive and negative. Like charges 

 repel and unlike charges attract. The energy 

 associated with two charged bodies is seated in 

 the ether which surrounds the two bodies and 

 is due to the electrical field or ether stress. 

 "When unlike charges approach, the energy of 

 the ether stress diminishes and the outside work 

 done by the attraction of the charges is equal 

 to the diminution of the energy of the ether 

 stress. Similarly, the energy of ether stress, 

 which is associated with two like charges, in- 

 creases when the charges are pushed towards 

 each other and the increase of the energy of the 

 ether stress is equal to the work done in push- 

 ing the two charges nearer together. 



In general, attraction of two bodies is to be 

 attributed to ether energy, which decreases as 

 the' bodies approach each other, and repulsion 

 of two bodies is to be attributed to ether energy, 

 which increases as the bodies are made to ap- 

 proach each other. Physicists have known this 

 many years and, as regards gravitation, no sat- 

 isfactory clue has yet been found concerning 

 the nature of the accompanying ether energy 

 and concerning its mode of propagation from 

 place to place. ' 



It is now pretty well established, that the 

 ether energy having to do with electrical at- 

 traction and repulsion is dependent upon a sort 

 oi shearing distortion of the ether unaccompanied 

 by any sensible diminution of volume, that this 

 ether distortion is what is known as electric field, 

 that the propagation of this energy constitutes 

 electrical waves, and that the movement of the 

 ether which comes into play during the establish- 

 ment of this shearing distortion, or which comes 

 into play while distortion at one place is re- 

 lieved and distortion at a contiguous place is 

 built up, is what is known as magnetic field. 



It may be that the ether distortion which we 

 call electrical field is accompanied by a very 

 slight diminution of volume of the ether, espe- 

 cially inasmuch as Maxwell showed that the 

 mechanical stresses in the dielectric tend to pro- 

 duce diminution of volume as well as to produce 

 shearing distortion. These mechanical stresses 

 are proportional to the square of the field inten- 

 sity at each point. 



If we admit that the diminution of volume of 



the ether at each point is proportional to the 

 resultant intensity of the electric field, then the 

 part of the energy which depends upon dimin- 

 ution of volume cannot be separated in its effects 

 from the part of the energy which depends 

 upon the shearing distortion, inasmuch as both 

 are proportional to the square of the resultant 

 field intensity. Therefore a diminution of vol- 

 ume of the ether could not explain gravitation, 

 but would only be involved in the explanation 

 of ordinary electric attraction and repulsion. 

 Professor Fessenden in his article above referred 

 to speaks quite in general of the compression of 

 the ether near a charged body (or ion) without 

 localizing this distortion. 



Before proceeding to a statement of what 

 must constitute the characteristic features of an 

 explanation of gravitation, as opposed to an ex- 

 planation of electric attraction and repulsion, 

 for the reader will certainly think of an expla- 

 nation of the one as applying satisfactorily to the 

 other also, so far as the above discussion goes, 

 it is necessary to outline briefly the present hy- 

 pothesis that the inertia of an atom, or rather 

 that the inertia of a corpuscle, is due to its 

 electric charge. 



It has been known for some years that a mov- 

 ing electrically charged body has more kinetic 

 energy for a given velocity than if it were not 

 charged ; that is, the acceleration of a charged 

 body by a given force is less than if the body 

 were not charged; that is, the inertia of a charged 

 body is greater than if it were not charged. 

 This excess of energy of a moving, charged 

 body — for the whole matter lies in the question 

 of energy — is due to two things, as follows: 



First, The dying away of the electric field in 

 regions passed through by the body and the 

 building up of electi-ic field in regions newly 

 reached by the body is accompanied by an 

 ether motion known as magnetic field, as 

 above stated, and this magnetic field repre- 

 sents energy. 



Second, The motion of a charged body tends 

 to concentrate the electrical field or ether 

 stress in and about a plane passing through the 

 body and at fight angles to the direction in 

 which the body is moving. This concentration 

 of the electric field causes, on the whole, an in- 

 crease in the total energy of the electric field. 



