Society of Glass Technology · [Sheffield] · leaf 351
By inserting a plate of selenite of such a thickness as to give * First used by Biot in 1813. 258 JOURNAL OF THE SOCIETY OF GLASS TECHNOLOGY. the sensitive violet tint* in the proper position under the analyserand above the object, the instrument is made much more delicate,and comparatively slight… … Fig. 2. A. Pile of plates (Polarisei). B. Nicol prism analyser with selenite plate. C. Wooden base. D. Square wooden tube, blackened inside, to exclude extraneous light. E. Space for article under examination. F. Window of finely-ground glass to diffuse incident light. H.M. Geological Survey…
Glass
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