. Motion picture electricity. n). Note that the purplearc in Fig. 108 cuts off almost fifty per cent, of theupper crater, reducing the candlepower. The crater ofthe lower carbon can barely be seen, as it is in its ownshadow, and besides it is below the line of focus and is,therefore, of no particular illuminating value. Notwithstanding the fact that the arc is extremely in-efficient when the carbons are set as illustrated in and 108, many operators continue to use this carbonsetting, because their current controllers do not permitthe setting of the carbons to advantage in any other wa
. Motion picture electricity. n). Note that the purplearc in Fig. 108 cuts off almost fifty per cent, of theupper crater, reducing the candlepower. The crater ofthe lower carbon can barely be seen, as it is in its ownshadow, and besides it is below the line of focus and is,therefore, of no particular illuminating value. Notwithstanding the fact that the arc is extremely in-efficient when the carbons are set as illustrated in and 108, many operators continue to use this carbonsetting, because their current controllers do not permitthe setting of the carbons to advantage in any other way. Fig. 109 is an exact reproduction of the c. arc in an 188 MOTION PICTURE ELECTRICITY ordinary moving picture machine lamp house operatingon 6o-cycle alternating current between two high gradey% in. soft cored carbons. The photograph from whichthis cut was made was taken after the arc had been in op-eration about three-quarters of an hour, so as to securea reproduction of the carbon points and the arc when innormal UpperGarboof Upper Grader^Short and White arc. in fdcuiwiCI) upper crater.^Exposed lower Crater m Focus witlrbotb upper Crater and Cbearc/ Lower Carbon. Fig. 109 I desire to call particular attention to the surfaces of theupper and lower craters, both of which are fully exposed,slanting at a slight angle, opening in wedge form towardthe condensing lenses, touching each other in the rearso as to form two perfectly white surfaces joining eachother at the extreme rear point. This form of crater per- MOTION PICTURE ELECTRICITY 189 mits the focusing of the upper and lower craters at thesame time with the same system of lenses in asingle spot,producing practically double the amount of illuminationas compared with the carbon setting illustrated in Fig. iooand Figs. 107 and 108. Attention is also directed to the arc in Fig. 109. Thearc is very short and is absolutely white, so that insteadof being a detriment like the long purple arc referredto above, the arc act
Size: 1229px × 2033px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1900, bookdecade1910, bookidmotionpictureele00hall
