United States. Surgeon-General's Office, American Roentgen Ray Society · New York : Middleditch · leaf 156
s are tfljbe made before any of them are operated it is most iessential that the various measurements and adjustments tbe accurately recorded. Hirtz Compass. Another graphic method using a widely different ap-plication of the triangulation process is the Compass ofHirtz 2b. In (Fig. 5) let R be the… … Fig. 5. Diagram of the Hirtz Compass.149 150 X-RAY MANUAL—U. S. ARMY accurately centered the direct ray from focus point V.The projectile is (P). A, B and C are three metal mark-ers at conveniently chosen points on the skin. If thefocus is displaced to F and to F, Fig. 6, and an exposuremade at…
