Читать книгу The American Electro Magnetic Telegraph. With the Reports of Congress, and a Description of All Telegraphs Known, Employing Electricity or Galvanism онлайн

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Fig. 12.

Fig. 13.

The second mode has but one wire and the ground, represented by ssss1. The use of the ground as a conductor of the galvanic fluid, between two distant points, is to many a mystery. But of the fact there is no question. The above diagram exhibits the manner in which the east wire and ground were used from the first operation of the Telegraph, until the close of the session of Congress, June, 1844. In this diagram, we will minutely follow the course of the galvanic current. B represents Baltimore, and W Washington; C represents a sheet of copper, five feet long and two and a half feet wide, to which a wire is soldered and connects with the N pole of the battery. This sheet of copper lies in the water at the bottom of the dock, near the depot of the Baltimore and Ohio Rail Road, Pratt street. From P of the battery, the wire proceeds to k, the key, then to m, the magnet or register, then it is the east wire to k′, the key at W, then to m′, the magnet or register, then to the copper sheet, C′, buried beneath the brick pavement in the dry dust of the cellar of the capitol. The direction of the current is from P of the battery to k, to m, and along the east wire to k′, to m′, and to C′, where it is lost in the earth; but reappears at the copper plate, C, at B, and thence to the N pole of the battery, having completed its circuit. It is, therefore, certain, that one-half of the circuit is through the earth. From B to W the east wire is the conductor; and from W to B the ground is the conductor. In this arrangement, the west wire is thrown out, and is no part of the circuit; while the earth has been made a substitute for it.