. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . ng of the battery 5 withthe line tends to set up in the line and toearth currents of opposite polarity to thoseresulting from the battery a, because the pos-itive of the one and the negative of the otherare to the ground and line, respectively, andthis local circuit (c a 3eb) serves to maintainan unbroken connection, that offers but littleresistance to the pulsation from the distantinstrument passing to the earth, and the re-sistance is nearly uniform to the current re-ceived, whether there is a current that is be-i
. Collection of United States patents granted to Thomas A. Edison, 1869-1884 . ng of the battery 5 withthe line tends to set up in the line and toearth currents of opposite polarity to thoseresulting from the battery a, because the pos-itive of the one and the negative of the otherare to the ground and line, respectively, andthis local circuit (c a 3eb) serves to maintainan unbroken connection, that offers but littleresistance to the pulsation from the distantinstrument passing to the earth, and the re-sistance is nearly uniform to the current re-ceived, whether there is a current that is be-ing sent or not. I claim as my invention— The battery a & in a local circuit, connectedto the line, in which is a circuit-breaker, afinger-key, in combination with the magnet Im, branch h, and resistance jc, and the induc-tion-coils / g, the parts operating substan-tially as set forth. Signed by me this 19th day of August, 1874. THOS. A. EDISON. Witnesses: Chas. H. Smith,Geo. T. Pinckney. No. 178,223. T. A. TELEGRAPH. Patented May 30, 1876. MAIN LINE. , PHOTO-LITHOGRAPHER, WASHING;GN. D C. United States Patent Office, THOMAS A. EDISON, OF NEWAEK, NEW JERSEY, ASSIGNOR OF ONE-HALFHIS RIGHT TO GEORGE B. PRESCOTT, OF NEW YORK CITY. IMPROVEMENT IN DUPLEX TELEGRAPHS. Specification forming part of Letters Patent No. 118,223, dated May 30,1876; application filed September 1,1874. To all tohom it may concern:J Be it known that I, Thomas A. Edison,of Newark, Essex county, New Jersey, haveinvented an Improvement in Duplex Tele-graphs, of which the following is a specifica-tion : | The trausmifcting-battery is connected withJthe line by a lever that simultaneously breakspe earth-connection, so as not to interruptthe continuity of the circuit. The currentSent divides and operates equally in twohelices. In one helix there is a sliding corepat moves with the armature of the otherhelix, and this latter responds to the pulsa-tion from the distant instrument and close
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