ix SCIENTIFIC MOTIVE 243 



now again on electro-magnetism, and think I have got 

 hold of a good thing, but can't say. It may be a weed 

 instead of a fish that, after all my labour, I may at last 

 pull up." 



A little later Faraday was able to show that when a 

 magnet is brought rapidly near a coil of wire, a slight 

 electric current is induced in the coil. Upon quickly 

 removing the magnet, a momentary current in the 

 opposite direction is created. Here, then, was a means 

 of producing electric current by the expenditure of 

 mechanical energy. All that was required was to set 

 a magnet in rapid motion near a coil of wire properly 

 arranged, and a supply of electricity could be obtained. 

 This was not fully realised, however, until many years 

 after Faraday performed the experiment to which the 

 electric dynamo owes its origin, though scientific men 

 understood the significance of the experiment. ' This 

 discovery of magneto-electricity," wrote Tyndall, " is 

 the greatest result ever obtained. It is the Mont 

 Blanc of Faraday's own achievements. He always 

 worked at great elevations, but higher than this he 

 never attained." 



Nearly fifty years elapsed before the discovery was 

 used with commercial success in the construction of the 

 dynamo ; and now as we travel at high speed upon 

 electric railways, and illuminate our streets and homes 

 with electric light, let us remember that we owe these 

 advantages to persistent and purely scientific experi- 

 ments made by Faraday at the Royal Institution 

 between the years 1824 and 1831. The new era of 

 electrical invention did not have its origin in the engineer- 

 ing workshop but in the scientific laboratory. 



Necessity is not the mother of invention ; knowledge and 

 experiment are its parents. This is clearly seen in the case of 



