Dr. Faraday's Thoughts on Hay-vibrations. 349 



or to and from the centre of action, whereas the former are 

 lateral. It seems to me, that the resultant of two or more 

 lines of force is in an apt condition for that action which may 

 be considered as equivalent to a lateral vibration ; whereas an 

 uniform medium, like the aether, 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 pro- 

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

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

 account for the phaenomena of radiation, it is necessary that 

 such vibration 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 of force being already in ex- 

 istence, such a lateral disturbance of them at one end as I 

 have suggested above, would require time, or must of neces- 

 sity be felt instantly at the other end. 



As to that condition of the lines of force which represents 

 the assumed high elasticity of the aether, it cannot in this re- 

 spect be deficient: the question here seems rather to be, whe- 

 ther the lines are sluggish enough in their action to render 

 them equivalent to the aether in respect of the time known ex- 

 perimentally to be occupied in the transmission of radiant 

 force. 



The aether 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 pene- 

 trate all space. As regards space, the difference is, that the 

 aether presents successive parts or centres of action, and the 

 present supposition only lines of action; as regards matter, 

 the difference is, that the aether 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 in- 

 tensity 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 aether, 

 namely the state of rare gas, how soon do we find in its elas- 

 ticity 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, had I not been led unawares, and without previous 



