THE DEBT OF THE WORLD TO PURE SCIENCE. 327 



macliine iu operation led him to test the effect of atmospheric electricity 

 iipou them. The instant action brought about the discovery that it was 

 due not to atmospheric influence, but to a current produced by contact 

 of a copper hook with an iron rail. Volta pursued the investigation and 

 constructed the pile which bears his name. With this, modified, Davy, 

 in 1807, decomposed potash and soda, thereby isolating potassium and 

 sodium. This experiment, repeated successfully by other chemists, 

 was the precursor of many independent investigations, which directed 

 to many lines of research, each increasing in interest as it was followed. 



Yolta's crown of cups expanded into the clumsy trough batteries 

 which were displaced finally in 1836 by Daniel's constant battery, using 

 two fluids, one of which was cupric sulphate. De la Eue observed 

 that, as the sulphate was reduced, the copper was deposited on the 

 surface of the outer vessel and copied accurately all markings on that 

 surface. "Within two or three years Jacobi and Spencer made the 

 practical application of this observation by reproducing engravings 

 and medals. Thus was born the science of electro-metallurgy. At first 

 mere curiosities were made, then electroplating in a wider way, the 

 electrotype, the utilization of copper to protect more easily destructible 

 metals, the preparation of articles for ornament and utility by covering 

 baser metals with copper or silver or gold, while now the development 

 of electro-generators has led to wide apijlications in the reduction of 

 metals and to the saving of materials which otherwise would go to 

 waste. 



Oersted, in 1819-20, puzzling over the possible relations of voltaic 

 electricity to magnetism, noticed that a conductor carrying an electrical 

 current becomes itself a magnet and deflects the needle. Sturgeon, 

 working along the same lines, found that soft iron inclosed in a coil 

 through which a current passes becomes magnetic, but loses the power 

 when the current ceases. This ojiened the way for our own Henry's 

 all-important discovery of the reciprocating electro magnets and the 

 vibrating armature — the essential parts of the magnetic telegraph. 

 Henry actually constructed a telegraph in 1832, winding the wires 

 around his class room in Albany and using a bell to record the making 

 and breaking signals. Here, as he fully recognized, was everything 

 but a simple device for receiving signals. 



Several years later Professor Morse, dreaming night and day of the 

 telegraph, was experimenting with Moll's electro-magnet and finding 

 only discouragement. His colleague. Professor Gale, advised him to 

 discard the even then antiquated apparatus and to utilize the results 

 given in Henry's discussion. At once the condition was changed, and 

 soon the ingenious recording instrument bearing Morse's name was 

 constructed. Henry's scientific discoveries were transmuted by the 

 inventor's ingenuity into substantial glory for Morse and proved a 

 source of inconceivable advantage to the whole civilized world. Stein- 

 hal's discovery that the earth can be utilized for the return current 



