Light, photometry and illumination : a thoroughly revedof ''Electrical illuminating engineering'' . Fig. 60.—The Bechstein form of Weber photometer. Another modification of the Weber photometer known as theBechstein form is shown in Fig. 60. A translucent plate Areceives the light to be measured and is viewed through the op-tical device H and the prism B. The comparison lamp C is abenzine lamp in this case. The photometric balance is obtainedmoving by the translucent plate G along the photometric axis; 126 LIGHT, PHOTOMETRY AND ILLUMINATION. Fig. 61.—Martens photometer (horizontal section).

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Keywords: ., bookcentury1900, bookdecade1910, booksubjectlight, bookyear1912