Roper's catechism for steam engineers and electricians .. (1899)
Roper, Stephen. [from old catalog], Keller, Edwin R., [from old catalog] ed, Pike, Clayton W., [from old catalog] ed · Philadelphia, D. McKay · leaf 366
needles back to their originalposition. STEAM ENGINEERS AND ELECTRICIANS. 345 Q. What is an automatic set-back annunciator ? A. One in which this rod is lifted by an electro-magnet so connected that current flows through itwhen any push-button is pressed. All the needlesare pushed back to their… … Signal Bell. Q. How does the return-call annunciator systemdiffer from this ? A. By the addition of another wire betweeneach push-button and the annunciator. Q. What is a fire-alarm attachment ? A. A device, frequently added to annunciatorsfor use in hotels, which closes the circuit of the 346…
Steam engineering · Electrical engineering
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