Hallberg, Josef Henrik, 1874- · New York city, The Moving picture world · leaf 226
s.The life of the bulb, the only part that requires renewal,averages 500 hours or more, and an allowance is made MOTION PICTURE ELECTRICITY 219 for the return of the terminals. While outfits for 60cycles are standard because 60-cycle circuits are mostcommon, similar outfits for other frequencies… … PRINCIPLES OF OPERATION The mercury rectifier consists essentially of a hermeti-cally sealed glass bulb filled with mercury vapor and pro-vided with four electrodes. The two upper electrodes(Fig. 116) are of graphite or other suitable material andthe two lower of mercury. The graphite electrodes…
Motion picture theaters · Electric lighting
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