. Radiography and radio-therapeutics . tothe j)endulum rod, and a cigar-shaped piece N is fixed in such aposition that the spring M, duringthe opposite swings of the pen-dulum, passes alternately aboveand below the piece N. At the end of N, and on its upper surface only, isa metal contact. N and M are electrically connected with the pilot lamp0, so that this lamp glows when the pendulum, moving from Kl to K,pulls M across the upper side of N. When the pendulum moves from Kto Kl, M passes on the under side of N and no contact is made. A frame S carries a thin wood panel PWP, against which the p
. Radiography and radio-therapeutics . tothe j)endulum rod, and a cigar-shaped piece N is fixed in such aposition that the spring M, duringthe opposite swings of the pen-dulum, passes alternately aboveand below the piece N. At the end of N, and on its upper surface only, isa metal contact. N and M are electrically connected with the pilot lamp0, so that this lamp glows when the pendulum, moving from Kl to K,pulls M across the upper side of N. When the pendulum moves from Kto Kl, M passes on the under side of N and no contact is made. A frame S carries a thin wood panel PWP, against which the patientleans. The lead lining P P has a window W exactly opposite the plate tobe exposed. A sheet of lead Q hangs down inside the revolving cassettes,but not touching them. Lead wings T are provided, as shown in Fig. combination of the lead sheets, P Q and T, stops any rays reaching anyplate except that one which is facing the window at the time of was originally intended that the tube X should be fired by the con-. -A rotating plate-cliiuiging ilevicSiilu elivatioii. ROTATING PLATE CHANGING STAND 113 tacts M N,but it was found that these soon burned up with the heavy currentsnecessary for quick exposures. The contacts are now connected to the pilotlamp 0, which indicates to the assistant in charge, looking through thewindow of the protected cabin U, when to pull over the spring switch ofthe single flash apparatus. The pendulum completes its double swnng intwo seconds, which gives time for the assistant to manipulate the switch,and for the table to bring a fresh plate into position. The single flash assuresthe sharpness of the negatives. With relatively slow exposures of one-tenthof a second the effects of vibration were visible on the plate. This form ofapparatus does not appear suitable for exposures at a quicker rate thanone plate in two seconds. A new type of apparatus is now being considered,with which it is hoped to expose up to eight plates in one seco
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