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An improved polarizing microscope. III. The slotted ocular and the slotted objective1

Published online by Cambridge University Press:  14 March 2018

A. F. Hallimond
Affiliation:
Museum of Practical Geology, London
E. Wilfred Taylor
Affiliation:
Messrs. Cooke, Troughton & Simms, Ltd., York

Extract

Measurements with the petrological microscope may be divided into those made with the orthoscopic and those with the conoscopic arrangements. It was early realized that if the micrometer scale or compensator was inserted in the focal plane of the ocular, the same apparatus would serve for measurements of both kinds, provided that a Bertrand lens was available. The method was described by A. B. Dick as early as 1888 in a form of microscope which has remained popular with many workers up to the present time. Additional slots at the level of the focal plane of the ocular were cut through the mount and the upper part of the microscope tube. Most European manufacturers, however, continued to provide only the usual slots in the lower part of the tube.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1948

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Footnotes

1

Published by permission of the Director, Geological Survey and Museum.

References

page 296 note 2 Dick, A. B., Min. Mag., 1888, vol. 8, pp. 160163.CrossRefGoogle Scholar

page 296 note 3 Berek, M., Zentralbl. Min., 1913, pp. 388, 427, 464, 580.Google Scholar

page 296 note 4 Ehringhaus, A., Zeits. Krist., 1931, vol. 76, pp. 315321.Google Scholar [M.A. 5–127.]

page 296 note 5 Wright, F. E., Amer. Journ. Sci., 1910, ser. 4, vol. 29, pp. 415417.CrossRefGoogle Scholar

page 296 note 6 Amann, J., Zeits. wiss. Mikroskop., 1894, vol. 11, p. 440.Google Scholar

page 297 note 1 Taylor, E. W., The inverting eyepiece and its evolution. Journ. Sci. Instruments, 1945, vol. 22, p. 43 CrossRefGoogle Scholar, especially fig. 10 and para. 10.

page 300 note 1 Rinne, F. and Berek, M., Anleitung zu optischen Untersuchungen mit dem Polarisationsmikroskop, 1934, p. 124.Google Scholar

page 300 note 2 Such methods were referred to as ‘stauroscopic’ in an earlier paper (Min. Mag., 1946, vol. 27, pp. 183–5). The original implication of this term seems rather obscure. It first appears in reference to the ‘stauroscope’ of von Kobell, by which extinction was adjusted with the aid of the interference-figure due to a calcite plate. It was later used, but rarely, as a general term for any methods of determining the extinction position ( Rosenbusch, H., Mikroskop. Physiogr., 5th edit. by Wülfing, E. A., 1921, vol. 1, pt. 1, p. 435 Google Scholar). ‘Conoscopic’ seems free from objection and will be employed instead.

page 301 note 1 J. Amann, loc. cit.