APPENDIX I: INVENTIONS 445 



" vulcanization," i.e. treatment with sulphur or certain sulphur com- 

 pounds (chloride, carbon bisulphide), a process introduced by Good- 

 year in 1839. 



ELECTRICAL APPARATUS; TELEGRAPH, TELEPHONE, ELECTRIC 

 LIGHTING, ELECTRIC MACHINERY. The first important applica- 

 tion of electricity to the service of man was the telegraph. This is 

 too well known to require more than the briefest description. An 

 electric circuit in a wire "made" or "broken" at one point is likewise 

 made or broken at all other points. Hence, it is only necessary to 

 employ a preconcerted system of make-and-break signals to dispatch 

 messages. This plan was first employed in 1836 by S. F. B. Morse, 

 a native of Charlestown, Massachusetts, and the first telegraph line 

 between two cities was installed between Baltimore and Washington 

 in 1844. The first transatlantic cable was laid in 1858. 



The telephone, invented by Alexander Graham Bell, is even more 

 familiar. This, also, depends on the making and breaking of an elec- 

 tric circuit, not (as is usual in the telegraph) by a key manipulated by 

 the finger, but by sound waves of the human voice impinging upon a 

 delicate membrane (the transmitter) and reproduced at a distance by 

 corresponding vibrations of another delicate membrane (the receiver). 



Wireless telegraphy and wireless telephony differ from ordinary 

 telegraphy and telephony merely in the use of signal waves set up in 

 the ether instead of signal waves (i.e. making and breaking) set up in 

 the current carried by a wire. Both arts are inventions of very recent 

 date. 



The electric light, which had long been known as a laboratory 

 experiment, became of practical utility about 1880, with the inven- 

 tion of the incandescent lamp, first the carbon arc and then the car- 

 bon filament, the former by Brush, the latter by Edison. 



The phonograph was invented by Edison in 1876, and was the 

 culmination of attempts extending over many years to record and 

 reproduce sound waves. In these attempts Young, Konig, Fleeming 

 Jenkin and many others participated. 



FOOD PRESERVING BY CANNING AND REFRIGERATION. In 1810 

 Appert of France succeeded in preserving foods in closed vessels by 

 heating and sealing while hot. In 1816 a small amount of food pre- 

 served in this way found its way into the British Navy, where its 

 value was recognized to some extent as a preventive of scurvy. It was 

 not, however, until after the American Civil War that the industry 



