162 



Intelligence and Miscellaneous Articles. 



at the surface ; (4) the action of atmospheric agents on the rocks 

 when exposed by denudation ; and (o) the changes induced by 

 pressure during the great movements to which rock-masses are 

 subjected. 



XXV. In 



nee and Miscella 



neous 



Articles. 



A SIMPLE WAY OF EXPLAINING CLERK MAXWELL S ELECTRO- 

 MAGNETIC THEORY OF LIGHT. BY MISS J. M. CHAMBERS, 

 B.SC* 

 r pHE following is how I have supposed the " series of oppositely 

 -■- directed magnetizations and electromotive forces " of C. 

 Maxwell's theory to arise. I do not in the smallest degree pretend 

 to comprehend his mathematics, and it is only from his verbal ex- 

 planation that I have formed the following conception of what his 

 meaning is. 



Suppose we have a straight linear conductor A B in which from 

 some cause or another a quantity of electricity is continually 

 bobbing up and down. "We know that the lines of magnetic force, 

 arising from these alternate up and down currents, will be circles 

 having the linear conductor for axis. Suppose we have a row of 

 these conductors parallel to one another. 



When the magnetic force-lines cut the next conductor ba, an 

 electromotive force of opposite sign to that in A B will be en- 

 gendered, in accordance with Lenz's law, and a current will ensue 

 which will in its turn be surrounded by magnetic force-lines. 

 When the current in A B is reversed, the induced one in a 6 will 

 be so too. 



The action of a b on a' b' will be the same as that of A B on a b; 

 and the same effects will be propagated along the whole line of 

 molecules. We have here the electromotive forces and the 

 magnetic forces acting in directions perpendicular both to one 

 another and to the direction of propagation, OX, as the theory 

 requires. Of course this explanation would be for a plane- 

 polarized ray. 



It seems to me that this explanation presents to the non-mathe- 

 matical mind, in a tangible form and in accordance with well-known 

 electrical phenomena, what may be the manner of production of 

 the " series of oppositely directed magnetizations and electromotive 

 forces." 



It is not necessary that the conductors should be linear ; we may 

 suppose them globular and touching one another, without inter- 



* Communicated by the Author. 



