THE DEBT TO PURE SCIENCE 27 



the copper was deposited on the surface of the outer vessel 

 and copied accurately all markings on that surface. Within 

 two or three j^ears 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 gen- 

 erators has led to wide applications 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 opened the way for our own Henry's all impor- 

 tant discovery of the reciprocating electromagnets and the 

 vibrating armature — the essential parts of the magnetic tele- 

 graph. 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. Pro- 

 fessor Gale, advised him to discard the even then antiquated 

 apparatus and to utilize the results given in Henry's discus- 

 sion. 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. Steinhal's discovery that the earth can be 

 utilized for the return current completed the series of funda- 



