Illuminating Engineering Society, Association of Public Lighting Engineers (Great Britain) · [London] · leaf 275
and instrumental errors dueto stray light or to partial cutting offof the light by the screening diaphragmswere eliminated. A disadvantage ofthis method is that if there is anyappreciable difference in the apparenttexture of the perforated screen and of thespecimen, the star hole does not… … Sliding lamp Fig. 44.—Blondels suggestion. believe. he wrote. that the samemethod with some little modificationcan be employed too. for the measurementof transmitive powers. The star screenis fixed perpendicularly on the bar OBand turns with it, the shaft being O.You can compare in that way the…
Lighting
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