Constructional data of Small Telescope objectives

Abstract

THE National Physical Laboratory has recently published through Messrs. Harrison and Sons a pamphlet with the above title. This has been prepared at the request of the Director-General of Munition Supplies, and is primarily intended for the assistance of manufacturers of optical instruments who are engaged in the production of optical munitions. The glasses on which the calculations are based are in all cases taken from the most recent catalogue of optical glasses issued by Messrs. Chance Bros, and Co., of Birmingham (February, 1915). The comprehensive character of the tables may be gauged from the fact that all the dense flints of this catalogue are severally combined with all the crowns, two dense barium crowns of high refractive index alone being excepted.