. How to make and use electricity ... moistened with a solu-tion of prussiate of potash. Each of the pens is simply asmall, pointed iron needle. Now, suppose that both of thepens are moved at the time and with the same rapidity acrosstheir respective sheets. The electric current, decomposingthe prussiate of potash, will cause the needle in New Yorkto trace a continuous blue line on Y, until the needle in Bos-ton reaches a line of sealing-^ax on X, when the circuit is 54 HOW TO MAKE AND broken a3 it-passes over this line. At the same time there isabreakinthe continuity of the line traced on Y.
. How to make and use electricity ... moistened with a solu-tion of prussiate of potash. Each of the pens is simply asmall, pointed iron needle. Now, suppose that both of thepens are moved at the time and with the same rapidity acrosstheir respective sheets. The electric current, decomposingthe prussiate of potash, will cause the needle in New Yorkto trace a continuous blue line on Y, until the needle in Bos-ton reaches a line of sealing-^ax on X, when the circuit is 54 HOW TO MAKE AND broken a3 it-passes over this line. At the same time there isabreakinthe continuity of the line traced on Y. If, further,each needle is moved down a hairs breadth each time it trav-erses ats respective sheet, theii we shall have an exact fac-similed the writing on the tin foil produced on the chemically-prepared paper, except that whereas the original is written indark letters on a light ground, the message is received-in lightletters on a dark ground. Pen and ink sketches of photographsand other pictures may be transmitted in the same The pens are not, of course, held and guided by humanhands, but by complex machinery. The rigorous exactnessrequisite in the movement of the two pens is secured by theabsolute synchronisms in the vibration of two pendulums, oneat each terminus, controlled by the electric current. Figure 3 represents a sectional view of the Bell consists of a steel magnet, A, about five inches long andthree-eighths of an inch in diameter, encircled at one extrem-ity by a short bobbin, on which is wound a coil, B, of verytine insulated wire; the ends of the coil, C C, are connectedwith the binding screws, DD. Immediately in front of themagnet is a thin, circular iron disk, E E. The whole is inclosedin a wooden or rubber case, F, with the exception that thewood is cut away at G, so as to expose one surface of the irondisk. The conical-shaped cavity serves the purpose of eithera mouth-piece or an ear trumpet. There is no difference be-tween the transmitti
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectricity, bookyear
