Electricity for public schools and colleges (1891)
Larden, W. (Walter), b. 1855 or 6 · London : Longmans · leaf 445
tion. The current from the sending station passes E E 4i8 ELECTRICITY CH. XXV. through the coils of the electro-magnet, and the iron keepera is attracted downward. This causes the other end of thelever to hit with a sharp sound the screw d. When the currentceases, the spring S pulls the lever down… … Fig. iii. the two sounds are separated by a corresponding interval, andthe sound is more deliberate. These two sounds can be readilydistinguished ; and by suitable combinations of these we can, aswill be explained in § 3, represent all the letters of the alphabet,and so form a code for messages. It…
Electricity
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