Half-shade Polarisers and Analysers

Abstract

GLAZEBROOK'S “Dictionary of Applied Physics” (vol. iv. p. 482) gives what purports to be the essential features of a Brace polariser, but is in fact a confusion of three devices, namely, the Brace half-shadow polariser, the Brace half-shadow elliptic analyser, and Tool's adaptation of the latter to Stokes's method of elliptic analysis. The object of this note is to clear away the obscurity which obviously exists with some otherwise well-informed writers in regard to the design and use of these different instruments.