(1) Geometrical Investigation of the Formation of Images in Optical Instruments, embodying the Results of Scientific Researches conducted in German Optical Workshops (2) Die Binokularen Instrumente: Nach Quellen und bis zum Ausgang von 1910 Bearbeitet

Abstract

AT a meeting of the Optical Society held in Cambridge on May 21 last, the future of geometrical optics formed the subject of an interesting discussion, in which the points of view of mathematicians and practical designers respectively were expressed. The subject has regained actuality in recent years in view of the undoubted superiority in optical design possessed by the German manufacturers in 1914, a superiority which proved a serious handicap to us in the manufacture of optical instruments such as range-finders, etc., required for military and naval purposes. The importance of this branch of knowledge was then realised; unfortunately, before the war the subject had been gradually dropping out of university curricula, the laborious algebra involved, and the stereotyped methods of treatment combining to render it distasteful to mathematical teachers and students. Relegated to a corner of the mathematical syllabus, geometrical optics was too often reduced to a few formulae crammed in a hurry, and it lacked the vitalising influence of really interesting, and practical illustrations. The manufacturing optical designer, on the other hand, tired of waiting for mathematical developments adequate to his needs, became increasingly empirical in his methods, and even now depends almost exclusively upon trigonometrical tracing of a few rays, which is, in fact, nothing else but trial and error. Probably this almost complete divorce between theory and practice accounts largely for the unprogressive character of pre-war British optical design as compared with the German.

(1) Geometrical Investigation of the Formation of Images in Optical Instruments, embodying the Results of Scientific Researches conducted in German Optical Workshops.

Edited by M. von Rohr. (Forming vol. 1 of “The Theory of Optical Instruments.”) Translated by R. Kanthack. Pp. xxiii + 612. Printed and published for the Department of Scientific and Industrial Research by H.M. Stationery Office, 1920. (From any bookseller or through H.M.S.O. at Imperial House, Kingsway, W.C.2, and 28 Abingdon Street, S.W.1; 37 Peter Street, Manchester; 1 St. Andrew's Crescent, Cardiff; 23 Forth Street, Edinburgh; or from E. Ponsonby, Ltd., 116 Grafton Street, Dublin.) 2l. 5s. net.

(2) Die Binokularen Instrumente: Nach Quellen und bis zum Ausgang von 1910 Bearbeitet.

By Prof. Moritz von Rohr. Zweite, Vermehrte, und Verbesserte Auflage. (Naturwissenschaftliche Monographien und Lehrbücher. Zweiter Band.) Pp. xvii + 303. (Berlin: Julius Springer, 1920.) 40 marks.