. The Dental cosmos. Holzknecht radiometer with index pastil inposition. which extends from the top to thebottom of the instrument. It is color-less at the top and gradually assumesa reddish brown tint as one progressesdownward. This band is stationary, andthe inner end of the sliding arm c isunder it. e is a small piece of colorlesscelluloid placed on the sliding arm, underwhich the measuring pastil b is is the scale of units generally em-ployed, and known as Holzknecht 5 show? the index pastil a in posi-tion in the sliding arm c and under the celluloid band d. Fig. 6 show
. The Dental cosmos. Holzknecht radiometer with index pastil inposition. which extends from the top to thebottom of the instrument. It is color-less at the top and gradually assumesa reddish brown tint as one progressesdownward. This band is stationary, andthe inner end of the sliding arm c isunder it. e is a small piece of colorlesscelluloid placed on the sliding arm, underwhich the measuring pastil b is is the scale of units generally em-ployed, and known as Holzknecht 5 show? the index pastil a in posi-tion in the sliding arm c and under the celluloid band d. Fig. 6 shows themeasuring pastil b also in nosition onthe sliding arm and under tlx.* piece ofcolorless celluloid e. It might be statedhere that the object of this small piece ofcolorless celluloid, which is always overthe measuring pastil, is to insure thatthe refraction will be the same for boththe index pastil and the measuring pas-til, g (Fig. 6) indicates where the Fig. Holzknecht radiometer with both the indexand measuring pastils in position. reading is made. Fig. T shows the slid-ing arm in a lower position. Here theindex pastil is under the dark or coloredportion of the colored celluloid band,while the measuring pastil, which hasnot been exposed to the ray. and there-fore has not changed in color, is underthe colorless piece of celluloid. Theillustration shows a distinct difference inthe shade of the two half pastils. Itwill be remembered that, when this slid-ing arm was in its original position(Fig. 6), both pastils were under color- 40 NIK DKXTAL COSMOS. less celluloid, and therefore at zero theyaccurately matched in shade. Now, how-ever, they do riot match, but if the meas-uring pastil had been exposed to the raysufficiently to have made it match theindex pastil, as demonstrated in Fig. 7,the reading would he 2IT units (at h). Fig. 7.
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Keywords: ., bookcentury1900, bookdecade1910, bookiddent, booksubjectdentistry
