. Archives of physical medicine and rehabilitation . planefurface. This is secured, in the stereo-scope, by a centrally placed light sourcearound which there are grouped reflect-ing walls of such design as to distributethe light on the opalite glass with ac-curate reproduction of the desiredformula. Then, a rheostat control that grad-ually increases or diminishes the in-tensity of the light until the individ-ual or subjective physiologic require-ment IS obtained by the observer. With this interestingly evolved in-strument of accuracy- the elementsof objective stereovision in roentgenog-raphy a
. Archives of physical medicine and rehabilitation . planefurface. This is secured, in the stereo-scope, by a centrally placed light sourcearound which there are grouped reflect-ing walls of such design as to distributethe light on the opalite glass with ac-curate reproduction of the desiredformula. Then, a rheostat control that grad-ually increases or diminishes the in-tensity of the light until the individ-ual or subjective physiologic require-ment IS obtained by the observer. With this interestingly evolved in-strument of accuracy- the elementsof objective stereovision in roentgenog-raphy are perfected; and there remainsonly to determine the individual sub-jective factor, which is accomplishedm this fashion: A wax model object, or adequatesubstitute, is prepared so as to containa foreign body at a given and knowndepth from the surface. The modelis then stereorcentgenographed and thecompleted films fitted into their properview boxes. The observer then visual-izes the part beginning with the lowestintensity of light (rheostat all in) ;. and gradually increases the light untilthe point is reached when the foreignbody is stereovisioncd at the fxact depththat It is known to be. When this isrealized, the observer has found hissubjective light intensity factor; andby keeping the rheostat fixed at thatposition, each subssquent examination isconducted uider ootrroum objective andsubjective cordiians that favor themost accurate ^fproach to ohysioloeicstereovision. By this means, the illu-sion of stereoscopy is removed; andthis form of rcertgen observation bs-rome; sce-t-fically based furnishingthereby a sourd method for the correct3nd rapid ^valuation of anatomic rela-tions, the ideal towards which stereo-scopy has, until now, futilely striven. Summary (1) and correct stereo-vision are not physiologically synony-mous. (2) Relief is a spurious is a true evaluation ofdepth based on subjective and objectvefactors. (3) Stersovis:on is accurate in pro
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