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Image from page 147 of “Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval” (1879)

Image from page 147 of

Identifier: supplementtospon02spon
Title: Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval
Year: 1879 (1870s)
Authors: Spon, Edward Byrne, Oliver Spon, Ernest Spon, Francis N
Subjects: Engineering
Publisher: London, fresh York, E. & F.N. Spon
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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Text Appearing Before Image:
divided into two branchesat K, one branch going directly to the earth by way of 2 and 1, passing through the coil r^, and theother by way of K, 3 and 4, passing through the coil r. For transferring the incoming currentfrom one of these branches to the other. Farmer employed a continuity preserving key K k upon thesame principle as that used by Nystrom in 1855. When the apparatus is in a position of rest, theroute of the incoming current is by way of 2, r^ and 1 to the earth at E. If the key K isdepressed, the circuit of the main battery is closed, by the contact of its rear end with the supple-mentary contact lever k, which is at the same time lifted from the point 2. The outgoing currentnow passes through the coil r of the relay at the home station, and through the coil r, at the dis-tant station. As the coil r, produces quite as great a magnetic eftect upon the relay R as the coilr, it is easy to so adjust the respective relays that the distant one shall attract its armature, while

Text Appearing After Image:
ELECTRICAL ENGINEERING. 523 that at the home station remains unaffected. When both keys are depressed, the circuit is throughthe coil r at each station, but the effect upon each relay is doubled, because the line is traversedby the combined current of two batteries. In order to render it certain that the receiving instru-ment at the home station should remain unaffected by the outgoing current, Farmer made useof the device employed by Gintl in 1855; an adjustable rheostat X placed in a branch ciicuit or Senduig Table, Rec&ivvyj Tcbble

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