Masterpieces of Science 



illustration; and guided by the principle he had 

 discovered, his wonderful mind, aided by his 

 wonderful ten fingers, overran in a single autumn 

 this vast domain, and hardly left behind him the 

 shred of a fact to be gathered by his successors. 

 And here the question may arise in some minds, 

 What is the use of it all ? The answer is, that if 

 man's intellectual nature thirsts for knowledge 

 then knowledge is useful because it satisfies this 

 thirst. If you demand practical ends, you must, 

 I think, expand your definition of the term prac- 

 tical, and make it include all that elevates and 

 enlightens the intellect, as well as all that minis- 

 ters to the bodily health and comfort of men. 

 Still, if needed, an answer of another kind might 

 be given to the question "what is its use?" 

 As far as electricity has been applied for medical 

 purposes, it has been almost exclusively Fara- 

 day's electricity. You have noticed those lines 

 of wire which cross the streets of London. It is 

 Faraday's currents that speed from place to 

 place through these wires. Approaching the 

 point of Dungeness, the mariner sees an unusually 

 brilliant light, and from the noble lighthouse 

 of La Heve the same light flashes across the sea. 

 These are Faraday's sparks exalted by suitable 

 machinery to sun-like splendour. At the present 

 moment the Board of Trade and the Brethren 

 of the Trinity House, as well as the Commissioners 

 of Northern Lights, are contemplating the in- 

 troduction of the Magneto-electric Light at 

 numerous points upon our coasts; and future 

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