The microscope and microscopical methods / by Simon Henry Gage...and illustrated by 165 text figures in the text.

  • Gage, Simon Henry, 1851-1944.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: The microscope and microscopical methods / by Simon Henry Gage...and illustrated by 165 text figures in the text. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    the field-lens aids the objective in the formation of the real, inverted image, and increases the field of view, it also combines with the eye-lens in rendering the im- age achromatic. i 36. Compensating Oculars.—These are oculars specially constructed for use with the apochrornatic objectives. They compensate for aberrations outside the axis which could not be so readily eliminated in the objective itself. An ocular of this kind, magnifving but twice, is made for use with high powers, for the sake of the large field in finding objects ; it is called a searching ocular; those ordinarily used for observation are in contradistinction called working oculars. Part of the compensating oculars are positive and part negative (Fig. 31). \ 37. Projection Oculars.—These are oculars especially designed for projecting a microscopic image on the screen for class demonstrations, or for photographing with the microscope. While they are specially adapted for use with apochrornatic objectives, they may also be used with ordinary achromatic objectives of large numerical aperture. Fig. 32. Projection Oculars with section re- moved to show the construction. Below are shown the upper ends with graduated circle to in- dicate the amount of rotation found necessary to focus the diaphragm on the screen No. 2, No. 4. The numbers indicate the amount the ocular magnifies the image formed by the objective as -with the compensation oculars. (Zeiss' Catalog, No. jo]. ft 3S. Micrometer Ocular.—This is an ocular connected with an ocular micrometer. The micrometer may be reinovahle, or it may be per- manently in connection with the ocular, and ar- ranged with a spring and screw, by which it may be moved back and forth across the field. (See Ch. IV). Fig. 33 Figs. 33-34 Ocular Micrometer with movable scale. Fig. 34. Fig. 33 w a side view of the ocular while Fig. 34 %iv?s a sectional end view, and shows the ocular microme- ter in position. In both the screw which moves the micrometer is shown at the left. (From Bausch & Lomb Opt. Co.)