136 ANNUAL OF SCIENTIFIC DISCOVERY. 



cable is ever laid, this seems the power destined to work it. Surely, 

 'the days of the galvanic battery seem to be numbered. 1 



" The invention above referred to is thus described by Commission- 

 er Holloway in his Report : 



"Conspicuous among the inventions which have received the sanc- 

 tion of letters patent is a magneto-electric telegraph, now in extensive 

 use in the United States Army for field purposes, and elsewhere for or- 

 dinary telegraphic purposes. This is a signal triumph in electro- 

 mechanics, for by the motive power of a small magneto-electric ma- 

 chine, occupying less than a cubic foot, a dial or index telegraph is 

 operated through great* distances, from 5 to 200 miles, with the pros- 

 pect of greater and indefinite extension. It was found with the Atlan- 

 tic telegraph, in 1853, that alternating, or to and fro currents, were 

 indispensable to its operation, and the magneto-electric machine of 

 the telegraph before us has the peculiar movement of normal to and 

 fro currents in rapid succession, without any extra contrivance for 

 their production, this condition growing out of the very arrangement* 

 of the magnetic poles and helices. The operators for this telegraph 

 require no training, and any person who can read can telegraph. For 

 the Morse telegraph two or three years of training are required. It 

 is not liable to piracy by tapping, as is the Morse telegraph, and may 

 be justly regarded as the inauguration of a new era in telegraphy, by 

 diseasing with the cumbersome, uncleanly, unhealthy, and inconstant 

 galvanic battery as the motive power, and the introduction of a simple 

 and economical telegraph, adapted with equal facility to domestic 

 and public purposes. It is not too much to say, that the days of tele- 

 graphing by the galvanic battery are numbered, and that the magneto - 

 electric machine will erelong take its place for this, as well as for 

 many other purposes. 



"Another highly interesting development in magneto-electric science 

 is the discovery and application of a new mode of ignition for pur- 

 poses of blasting with powder. Hitherto torpedoes and other powder 

 blasts, iired by electricity, have depended upon the ignition of a very 

 fine platinum wire. When this had to be done through long circuits, 

 or at great distances, very large and expensive galvanic batteries were 

 required, owing to the great diminution of the quantity of electricity. 

 It was proved by experiments made at the Capitol many years since, 

 that l.">0 pairs of Grove's battery were necessary to ignite powder by 

 the finest of platinum wires placed in the telegraph circuit between Bal- 

 timore and Washington, a distance of 40 miles. By means of the new 

 discovery, powder has been fired through the distance of 100 miles by 

 means of a little magneto-electric machine, occupying less than a cubic 

 foot. This astonishing achievement has been accomplished by means 

 so simple that electricians will wonder a*s much, if not more, than the 

 uninitiated. It is done ; by a pencil-mark. The stroke of a common 

 black-lead pencil on a block of wood is substituted for the platinum 

 wire, and this disintegrated conductor, as it may be called, is so in- 

 tensely ignited by the magneto-electric current as to set fire to the 

 wood. 



"The application of this ingenious device within a suitably-pre- 

 pared cartridge, will be hailed as one of the^most valuable contribu- 

 tions to mining and engineering operations 01 the present day." 



