This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1919 Excerpt: … on the line. The target was bright red. No harm had been done to the tube, but it would have been unsafe to continue without interruption. With intermittent operation, it was found that a 6-second exposure with 30 milliamperes at a 5-inch useful gap could be repeated indefinitely with 40 second intervals between exposures. With suitable intervals between, exposures with 30 ma. ranging in time from 0 to 35 seconds could then be made. Medium Focus T-inch Tube With Solid Tungsten Target, Operated From Transformer (without Rectifer) Starting with the target at room temperature, this tube was operated with 30 milliamperes at a 5-inch useful gap for 10 seconds. At the end of this time it showed green fluorescence at the cathode end, indicating that it was beginning to pass inverse current. The target was red hot. Experience has shown that had the operation of this tube been continued further without interruption, it would have been put permanently out of commission, either from cracking the bulb back of the cathode or from deterioration of vacuum. After waiting 15 minutes for the target to cool, it was found that the tube would carrT the 30 ma. load for ‘t/2 seconds, at the end of which time, inverse again appeared. After a further wait of 21 minutes, it was possible to operate it for 7 seconds This tube then would have stood from a cold start, a single 30 ma. exposure of 10 seconds, and repeated exposures of 6 seconds duration with intervals of about 20 minutes between. Broad-focus T-inch Tube With Solid Tungsten Target, Operated From Transformer (without Rectifier) Experiment showed that this tube could be run with 30 milliamperes at a 5-inch gap for 6-second exposures at intervals of 15 minutes Further Considerations With the present design, the 7-inch tubes …
