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This eBook from the Gutenberg Project consists of approximately 107 pages of information about Scientific American Supplement, No. 312, December 24, 1881.
opposite the wick serves for producing the light.  The pile is a bichromate of potash element, in which there is substituted for the liquid a solution of bichromate identical with that used in bottle piles.  The zinc is suspended from a small lever, in which it is only necessary to press slightly to bring the former in contact with the asbestos paste, when, the zinc being attached, a current is set up which traverses the spiral, heats it to redness, and lights the spirit.  The pile, when once charged, may be used for several hundred lightings.  When the spiral no longer becomes red hot, it is only necessary to replace the paste—­an operation of extreme simplicity.  When the pressure is removed from the little lever, the zinc, being raised, is no longer acted upon by the liquid with which the asbestos is saturated.  Mr Desruelles is constructing upon the same principle a gas lighter, the pile of which is fixed at the extremity of a handle whose length varies with the height of the gas burners to be reached.  These little domestic apparatus are being exhibited at the Paris Electrical Exhibition.

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SOLENOID UNDERGROUND WIRES IN PHILADELPHIA.

The Evening Bulletin of the 29th October has the following: 

This afternoon a series of experiments were conducted at the Public Buildings which will be of great interest to electricians all over the country, and upon which the success of a number of underground telegraph projects in different parts of the United States depends.  In all projects of this kind the problem which has given most trouble to inventors has been to overcome the induction.  In other words, electric currents will leave their original conductors and pass to other conductors which may be near at hand.  This interchange of currents may take place without seriously hindering ordinary telegraphy, as the indicators are not delicate enough to detect the induction.  When telephones came into use, however, the induction became a great source of trouble to electricians, it often being the case that the sounds and influences from without were sufficient to drown out sounds in a telephone.  To-day’s experiment was conducted by Mr. J.F.  Shorey, a well-known electrician, who exhibited Dr. Orazio Lugo’s cables for electric light, telephone, and telegraphic purposes.

A large number of prominent electricians were present, including the following:  General J.H.  Wilson, President of the N.Y. and N.E.  Railroad, of Boston; Messrs. Frank L Pope, S.L.M Barlow, George B. Post, Charles G. Francklyn, Col.  J.F.  Casey, W.H.  Bradford, and Selim R. Grant, of New York; James Gamble, General Manager of the Mutual Union Telegraph Co.; T.E.  Cornich and W.D.  Sargent, of the Bell Telegraph Co.; S.S.  Garwood and J.E.  Zeublen, of the Western Union, and others.

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