Addyman, Frank Thornton · London : Scott, Greenwood & co. · leaf 121
d, it has become fainter until, a little later, it is quiteinvisible. An accurate focalising of the cathode stream on the anode,which starts all the X rays from a single well-rounded spot,is the condition which determines well-defined shadows, andenables us to take sharp radiograms, with many… … Fig. 32.—Pin-hole Camera. glow. If a very tiny, well-rounded red-hot spot forms on theplatinum, the tube will probably give good definition. If alarge spot of irregular shape, or several spots at once growred-hot, the tube should be rejected. But since tubes are a heavy item in the expenditure of…
X-rays
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