Electric R. Signal Co. v. Hall Ry. Signal Co.,
114 U.S. 87 (1885)

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U.S. Supreme Court

Electric R. Signal Co. v. Hall Ry. Signal Co., 114 U.S. 87 (1885)

Electric Railroad Signal Company v. Hall Railway Signal Company

Argued January 6-7, 1885

Decided March 30, 1885

114 U.S. 87


Patent, No. 140,536, granted July 1, 1873, to Frank L. Pope for an improvement in electric signaling apparatus for railroads, was for a combination of several previously known parts or elements, to be used together in effecting the desired result of signaling, among which parts so used, and essential to the combination, was an insulated section or insulated sections of the track of the railroad on which the device might be used.

In practical operation, the device protected by that patent required independent devices to equalize the resistance in the different circuits.

The device patented to Thomas S. Hall and George H. Snow, by patent 165,170, granted July 13, 1875, for an improvement in operating electric signals, dispensed with the use of insulated sections of the track, and used instead thereof the earth for the return current to complete the circuit, and arranged its conductors with reference to the batteries and magnets so as to equalize the resistance in the circuits when the signals were operated by a single battery.

The device patented to Hall and Snow differs from that patented to Pope in the elements which form the combination, in the functions performed by them, in the arrangement of the parts, and in the principle of the combination, and the rights protected in the latter are not infringed by the use of the former.

This was a suit in equity to restrain an infringement of a patent for an improvement in electric signaling for railroads. The defense denied the priority of invention and denied the infringement. The facts which make the case are fully stated in the opinion of the Court.

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