1846.] Thoughts on Hay-vibrations. 371 



is in an apt condition for that action which may be considered as 

 equivalent to a lateral vibration ; whereas a uniform medium, 

 like the ether, does not appear apt, or more apt than air or water. 

 The occurrence of a change at one end of a line of force easily 

 suggests a consequent change at the other. The propagation 

 of light, and therefore probably of all radiant action, occupies 

 time ; and, that a vibration of the line of force should account 

 for the phenomena of radiation, it is necessary that such vibra- 

 tion should occupy time also. I am not aware whether there 

 are any data by which it has been, or could be ascertained, 

 whether such a power as gravitation acts without occupying 

 time, or whether lines offeree being already in existence, such 

 a lateral disturbance of them at one end as I have suggested 

 above, would require time, or must of necessity be felt instantly 

 at the other end. 



As to that condition of the lines of force which represents 

 the assumed high elasticity of the ether, it cannot in this respect 

 be deficient : the question here seems rather to be, whether 

 the lines are sluggish enough in their action to render them 

 equivalent to the ether in respect of the time known experi- 

 mentally to be occupied in the transmission of radiant force. 



The ether is assumed as pervading all bodies as well as space: 

 in the view now set forth, it is the forces of the atomic centres 

 which pervade (and make) all bodies, and also penetrate all 

 space. As regards space, the difference is, that the ether 

 presents successive parts or centres of action, and the present 

 supposition only lines of action ; as regards matter, the difference 

 is, that the ether lies between the particles, and so carries on 

 the vibrations ; whilst as respects the supposition, it is by the 

 lines of force between the centres of the particles that the 

 vibration is continued. As to the difference in intensity of 

 action within matter under the two views, I suppose it will be 

 very difficult to draw any conclusion ; for when we take the 

 simplest state of common matter and that which most nearly 

 causes it to approximate to the condition of the ether, namely 

 the state of rare gas, how soon do we find in its elasticity and 

 the mutual repulsion of its particles, a departure from the law, 

 that the action is inversely as the square of the distance ! 



And now, my dear Phillips, I must conclude. I do not think 

 I should have allowed these notions to have escaped from me, 



