18 PROFESSOR HENRY AND THE 



useful. The brilliant spark which follows the 

 pulling of the pendant, attached to an electric 

 lighter for inflaming a gas jet, now in common 

 use, is one of the valuable practical applications 

 of this principle so discovered. 



In contemplating the discoveries of the scientist 

 there are two aspects in which they present them- 

 selves. In one view we consider merely the diffi- 

 culty of the achievement; in the other, the value 

 of the result to mankind. The first view is ob- 

 vious when the thing is done; the other is to be re- 

 served fora future day, when all the consequences 

 have followed the original cause. The first view 

 is that which measures the power of the man 

 just as the lifting of a huge weight by some Her- 

 cules exhibits his strength, even though the 

 thing done may be, or may seem to be, useless. 

 The capital discoveries I have named, made by 

 Henry and Faraday, exhibited the giant's strength 

 when they were made, and measured the men 

 who made them. They were found at great 

 depths below the surface, where mental vision can 

 only penetrate by the aid of lenses, constructed in 

 advance, in accordance with the very laws for 

 whose discovery they are needed creations of the 

 scientific imagination, and called scientific hy- 

 potheses. In such creations Professor Henry was 

 excelled by no man. 



Time will not permit even a hasty review of all 



