542 POPULAR LECTURES AND ADDRESSES. 



light ; but no result came from those experiments. 

 About the same time or soon after, certainly not 

 long before the end of his working time, he was 

 engaged (I believe at the shot tower near Waterloo 

 Bridge on the Surrey side) in efforts to discover 

 relations between gravity and magnetism, which 

 also led to no result. 



Absolutely nothing has hitherto been done for 

 gravity either by experiment or observation 

 towards deciding between Newton and Bernoulli, 

 as to the question of its propagation through a 

 medium, and up to the present time we have no 

 light, even so much as to point a way for investiga- 

 tion, in that direction. But for electricity and 

 magnetism, Faraday's anticipations and - Clerk- 

 Maxwell's splendidly developed theory have been 

 established on the sure basis of experiment by 

 Hertz's work, of which his own most interesting 

 account is this year presented to the world in the 

 German and English volumes to which I have 

 referred. It is interesting to know, as Hertz 

 explains in his introduction, and it is very im- 

 portant in respect to the experimental demonstra- 



