684 LAMP-LIGHTING BY ELECTRICITY. 



him on cross examination — the testator will repeat his last will and testa- 

 ment into the machine so that it will be reproduced in a way that will leave 

 no question as to his devising capacity or sanity. It is already possible by 

 ingenious optical contrivances to throw stereoscopic photographs of people 

 on screens in full view of an audience. Add the talking phonograph to 

 counterfeit their voices, and it would be difficult to carry the illusion of 

 actual presence much further. — Scientific American, December 2>2d., 1877. 



Mr. Thomas A. Edison, the inventor of the talking phonograph which 

 we recently described, informs us that he has constructed a new and larger 

 macbine which not merely speaks with all the clearness which we predicted 

 would be obtained, but loud enough to be audible at a distance of 175 feet. 

 — Scientific American, Jan. 5, 1878. 



LAMP- LIGHTING BY ELECTRICITY. 



Such is the progress the science of electricity is making in the hands of 

 its practical exponents, that we have now to record the fact that any num- 

 ber of the street lamps can be dealt with — that is London or any other town 

 can have the whole of its public gas lamps turned on, lighted, and turned 

 off instantaneously, with ease and, so far as at present has been seen, with 

 'certainty. The highly ingenious invention by which this is accomplished 

 is due to Mr. St. George Lane Fox, and is on trial at the station of the Gas- 

 light and Coke Company at Fulham, where we recently inspected its prac- 

 tical working. The arrangements by which a revolution in our public 

 iamp-lighting promises to be effected consists, in the first place, in connect- 

 ing the lamps together by conductors, consisting of insulated metallic 

 wires. By this means an electric current, generated at a station or cen- 

 tral point, operates simultaneously upon every lamp through the instru- 

 mentality of an apparatus attached to each lamp. The apparatus consti- 

 tutes the special feature of Mr. Fox's invention. It is difficult without 

 drawings to describe precisely this ingenious piece of mechanism, but 

 broadly it may he stated to consist mainly of a soft iron core, around which 

 is a coil of insulated wire, thus forming an electro magnet. The wire of 

 this electro magnet forms part of the electric circuit by which the lamps 

 are connected, and constitutes in itself a primar}'" coil. Around this pri- 

 mary coil is wound a secondary coil of fine wire of much greater 

 length. We thus have an induction coil and a fixed magnet, which can be 

 magnetized so as to render its poles reversible at pleasure. Above this 

 fixed magnet is a permanent steel magnet, which, however, is moveable, 

 being free to turn on a needle point forming a vertical axis, thus affording 

 it the means of developing a reciprocating horizontal motion when actu- 

 ated. These magnets are carried in a small metal framing, having a passage 

 through it for the gas to pass to the burner at the top, and being provided 



