. Chamber's scientific reader : illustrated with wood engravings. Readers. 36 PHYSICS. other part of the circuit—the part played by the liquid in fig. 34 ? In the case of the telegraph, the earth is substituted for the liquid, for if the wire which goes along the lines be attached to the copper plate of the battery, and a wire, attached to the zinc, be carried down into the earth, the circuit is complete. In fig. 38, then, L is the line-wire, and E the earth-wire, both of which are made continuous with the coils of wire on the electro- magnet, MM'; the armature, A, is attached to a lever, IV,
. Chamber's scientific reader : illustrated with wood engravings. Readers. 36 PHYSICS. other part of the circuit—the part played by the liquid in fig. 34 ? In the case of the telegraph, the earth is substituted for the liquid, for if the wire which goes along the lines be attached to the copper plate of the battery, and a wire, attached to the zinc, be carried down into the earth, the circuit is complete. In fig. 38, then, L is the line-wire, and E the earth-wire, both of which are made continuous with the coils of wire on the electro- magnet, MM'; the armature, A, is attached to a lever, IV, which turns on the axis h. Whenever the current is made to pass through the wire, the armature is drawn down, bringing the end of the lever with it; this raises the other end, to which is fixed a sharp point, p; opposite this point is a. Mr^> =f2-__ IF"";- S^Sfgjy iiJiiF?^!iii!iaiii:;w:iW Fig. 38. groove in the roller, r, and over this groove is made to pass a slip of paper, PP', which is made to move towards P' by the rollers, rr'. These rollers are worked by clock-work, independently of the rest of the machine. When the point p is raised into the groove on the roller r, a raised mark is made on the upper surface of the paper, which will be a dot or a line according to the time the point is raised, that is, according to the time the circuit is kept complete ; as soon as the current ceases, the armature is left by the magnet free to rise, and the end of the lever, with the point, is pulled down by the spring s. By means of the dots and lines thus made on the paper, an alphabet is constructed, and words can thus be written down at the dis- tance of thousands of miles. But now, how is this system of stopping and setting agoing of the current managed at the sta- It is done by what is called a key,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrati
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherlondo, bookyear1872
