The telephone: an account of the phenomena of electricity, magnetism, and sound, as involved in its action (1877)
Dolbear, A[mos] E[merson], 1837- [from old catalog] · Boston, Lee & Shepard; New York, C. T. Dillingham · leaf 127
timeholds the soft-iron rods with the bobbins uponthem. The wires on these coils must be connect-ed in the same way they would be in order tomake opposite poles of their outer ends, if a cur- 122 THE TELEPHONE. rent of electricity were to be sent through thecoils. An upright board B (Fig. 17) six… … FIG. 16. sheet iron or steel; it may be from the one-twen-tieth to the one-fiftieth of an inch in thickness.It does not seem to make much difference aboutthe thickness of this plate. I have generally gotthe best results from a plate one-fiftieth of an inchthick. The upright board carrying this…
Telephone
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