Scientific American Supplement, No. 358, November 11, 1882 by Various
page 74 of 139 (53%)
page 74 of 139 (53%)
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of insulated wire is suspended, like the pendulum of a clock, between
these permanent magnets, in such a manner that the bobbin hangs just in front of the four poles. A counterpoise is fixed at the top of the pendulum bar, which permits the adjusting of the antagonistic forces represented by the action of the swinging bobbin, and two springs, which are insulated from the mass, and which form one electrode of the local or annunciator circuit, while the pendulum bar forms the other. It will be easily understood that as the bobbin hangs freely in the center of a very strong magnetic field (formed by the four poles of the two permanent magnets), the slightest current sent through the bobbin will cause the bobbin to be attracted from one direction, while it will be repelled from the other, according to the polarity of the current transmitted. As the relay has a very low resistance, it is evident that it will become an acceptable auxiliary in our central office, particularly when used as a "calling off" signal, as by its use the ground deviation, so objectionable and yet so universally used for "calling off" purposes, can be entirely avoided, and the relay left directly in the circuit, as is being done here in Paris. R. G. BROWN. Paris, September 12, 1882. * * * * * THE PLATINUM WATER PYROMETER. |
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