6i6 THE POPULAR SCIENCE MONTHLY, 



deavoring to sustain his false theory by experimental proofs, was led 

 to the discovery of the voltaic pile, or, as we now call it, the voltaic 

 battery, an instrument whose influence on civilization can be compared 

 only with the printing-press and the steam-engine. Yet, although the 

 whole action of the battery was in direct contradiction to his pet the- 

 ory, still, to the last, Yolta persistently defended the erroneous doc- 

 trine he had espoused in his controversy with Galvani thirty years 

 before, and he died in 182*7, without realizing how great a boon he 

 had been instrumental in conferring on mankind ; so true it is, that 

 Providence works out her bright designs even through the blindness 

 and mistakes of man. 



But there is another lesson to be learned from this history, which 

 cannot be too often rehearsed in this self-suflicient age, which boasts 

 so proudly of its practical wisdom. There were, doubtless, many prac- 

 tical men in that city of Bologna to smile at their sage professor who 

 had spent ten long years in studying, to little apparent purpose, the 

 twitchings of frogs' hind-legs, and there was many a jest among the 

 courtiers of Europe at the expense of the learned philosophers who 

 " wasted " so much time in discussing the cause of such trivial phe- 

 nomena. But how is it now ? 



Less than a century has passed since Galvani's death ; and, in a 

 small hut, on the shores of Valentia Bay, may be seen one of the most 

 skillful of a new class oi practical men^ representing a profession which 

 owes its orio^in to Galvani and Yolta. This electrician is watching: a 

 spot of light on the scale of an instrument which is called a galvanom- 

 eter. Since the fathers fell asleep, the field of knowledge which they 

 first entered has spread out wider and wider before the untiring ex- 

 plorers who have succeeded them. Oersted and Seebeck, Arago and 

 Ampere, Faraday and our own Henry, have made wonderful discov- 

 eries in that field ; and other great men, like Steinheil, Wheatstone, 

 Morse, and Thomson, have invented ingenious instruments and appli- 

 ances, by which these discoveries might be made to yield great prac- 

 tical results. 



The spot of light, which the electrician is watching, is reflected 

 from one of the latest of these inventions — the reflecting galvanometer 

 of Thomson. He and his assistants had been watching by turns the 

 same spot for several days, since the Great Eastern had steamed from 

 the bay, paying out a cable of insulated wire. These electricians had 

 no anxiety as to the result, for daily signals had been exchanged be- 

 tween the ship and the shore, as hundreds after hundreds of miles of 

 this electrical conductor had been laid on tlie bed of the broad ocean. 

 The coast of Newfoundland had already been reached, and they 

 were only waiting for the landing of the cable at the now far- distant 

 end. 



At length the light quivers, and the spot begins to move ! It 

 answers to concerted signals ! And soon the operator spells out the 



