. Elementary and dental radiography / by Howard Riley Raper . Fig. 109. Radiograph ma^t Crom pose illustrated in Fig. 10S. 120 DENTAL RADIOGRAPHY anteroposterior view of the frontal sinuses, the ethmoid cells and theantra. (A better pose is illustrated and diagramed in Appendix ) Observe Figs. 112 and 113 made from this pose. (Figure inshows one end of a small chain attached to the metal of the tube-manipu-lating apparatus. The other end of the chain is attached to a gas jet orwater pipe. This is called grounding the current to keep it from jump-ing a small air gap into the patient. The
. Elementary and dental radiography / by Howard Riley Raper . Fig. 109. Radiograph ma^t Crom pose illustrated in Fig. 10S. 120 DENTAL RADIOGRAPHY anteroposterior view of the frontal sinuses, the ethmoid cells and theantra. (A better pose is illustrated and diagramed in Appendix ) Observe Figs. 112 and 113 made from this pose. (Figure inshows one end of a small chain attached to the metal of the tube-manipu-lating apparatus. The other end of the chain is attached to a gas jet orwater pipe. This is called grounding the current to keep it from jump-ing a small air gap into the patient. The tube is, of course, insulatedfrom the metal of the tube-manipulating apparatus and cylinder, but, be-cause the electric current in use is of such high potential or pressure,. Fig. 110. Tube stand with attachment for making extra-oral radiographs. (Photograph by Dr Eisen.) some current may, nevertheless, get into the metal parts, and from thereto the patient. With a small chain, or any electric conductor, attachedto the metal of the tube-manipulating apparatus and the other end at-tached to a gas jet or water pipe the current will not jump an air gapinto the patient but will pass into the chain and through it to the gas orwater pipe, eventually reaching the earth possibly—hence the namegrounding. If the current jumps a small air gap into a patient a spark-occurs, due to the atmospheric resistance, and the sensation experiencedby the patient is very definitely unpleasant.) Figure 114 is, in results obtained, the same as the pose illustrated in MAKING DENTAL RADIOGRAPHS 121 Fig. in. In Fig. 114 an incline plane is used and the rays are directedstraight downward. A studied observation of Fig. 112 will reveal to the reader a hori-zontal shadow across the antr
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