Electrical and scientific instruments and apparatus : november 20th, 1899 (1899)
Elmer G. Willyoung & Co · New York : E.G. Willyoung · leaf 172
galvanometers. The mirror will then deflect on the closure of thiscurrent and since the film is passing before this slit the motion of themirror will be recorded as a connecting photographic curve. The needles are made so small that a frequency up to 8,000 to 10,000double vibrations per second can… … Fig. 141: HOTCHKiss Oscillograph (Assembled).
Electric apparatus and appliances · Equipment and supplies
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