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 125
orbing the vibrations, &c.; and it is reallysurprising, how little is the difference betweenvery wide limits. The following directions willenable any one to construct a speaking-telephonewith which good results may be obtained. Thespecifications will be for only one instrument; 120 THE… … FIG. 15. retail in the market at about a dollar apiece.They should be strong enough to hold up severaltimes their own weight each. Next, have turnedout of good hard wood, — such as maple or box-wood, — two spools not over half an inch longand an inch and a half broad, the sides cut HOW TO MAKE A…
Telephone
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