. American X-ray journal . h the vacuum of the tube, con-sequently it is not possible to insure sharpdefinition under all conditions with eventhe best tubes, and in constructing atube the maker is obliged to guess at thebest distance to make between the kathodeand the anti-kathode. There is noway oftesting the accuracy of his guess until thetube is exhausted and properly excited. In my new tube the anti-kathode ismounted on a threaded stem which can bemagnetically operated thru the glass, soas to move it up or down or circumfer- of the anode. It will stand an unlim-ited degree of heat and unli
. American X-ray journal . h the vacuum of the tube, con-sequently it is not possible to insure sharpdefinition under all conditions with eventhe best tubes, and in constructing atube the maker is obliged to guess at thebest distance to make between the kathodeand the anti-kathode. There is noway oftesting the accuracy of his guess until thetube is exhausted and properly excited. In my new tube the anti-kathode ismounted on a threaded stem which can bemagnetically operated thru the glass, soas to move it up or down or circumfer- of the anode. It will stand an unlim-ited degree of heat and unlimited usage,even with the sharpest focus. The difference between x-ray work donewitli a properly focused tube and thatdone with a tube out of focus may be ap-preciated by holding a wire screen (20mesh) between the tube and the fluoro-scope, with the latter twenty-four inchesdistant. When the tube is perfectly fo-cused the holes may be distinctly seenwith the screen at least twelve incheadistant. With a poor focus it may be. entially with the surface of the tube, inorder to obtain an accurate focus. Themethod of operating is illustrated in thefigure. The little armature on which themagnet acts cannot get out of adjustmentand will hold the anode in any requiredposition, either in focus for radiographicwork, or out of focus as is sometimes re-quired for therapeutic purposes. In my tube the anti-kathode is made ofplatinum especially thickened at the cen-ter and electrically welded to the body necessary to bring the screen close to thefiHoroscope. [This kind of tube has been neededfor a long time. Every radiographer hashad endless difficulties in selecting theright tube for a particular piece of are satisfied that in many cases thedifficulty has been with the focus of thetuba The fact that the focal distancechanges with the vacuum of the tubemakes an adjustable device of the great-est importance for accurate work.—En.] Same Experiments and Conclusions in Hypnotic Therapeut
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