File:The microscope - an introduction to microscopic methods and to histology (1911) (14578177440).jpg

Identifier: microscopeintrod11gage (find matches)
Title: The microscope : an introduction to microscopic methods and to histology
Year: 1911 (1910s)
Authors: Gage, Simon Henry, 1851-1944
Subjects: Microscopy Microscopes
Publisher: Ithaca, N.Y. : Comstock Pub. Co.
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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tend directly across the spectrum. $ 191. Focusing the Slit.—-In order that the lines or bands in thespectrum shall be sharply defined, the eye-lens of the ocular should beaccurately focused on the slit. The eye-lens is movable, and when theprism is swung aside it is very easy to focus the slit as one focused forthe ocular micrometer (§ 161). If one now uses daylight there will b?seen in the spectrum the dark Fraunhofer lines (Fig. 116 E. F., etc.). To show the necessity of focusing the slit, move the eye-lens downor up as far as possible, and the Fraunhofer lines cannot be seen.While looking into the spectroscope move the ocular lens up or down,and when it is focused the Fraunhofer lines will reappear. As the dif-ferent colors of the spectrum have different wave lengths, it is necessaryto focus the slit for each color if the sharpest possible pictures are desired. It will be found that the eye-lens of the ocular must be farther from 126 MICRO-SPECTROSCOPE AND POLAR/SCOPE. (CH. VI.
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Fig. 117. Fig. 118. Fig. 119. Fig. 117 (1). Section of the tube and stage of the microscope with the spectralocular or micro spectroscope in position. Amici Prism (g 167). — The direct vision prism of Amici in which the centralshaded prism of flint glass gives the dispersion or separation into colors, while theend prisms of crown glass cause the rays to emerge approximately parallel withthe axis of the microscope. A single ray is represented as entering the prism andthis is divided into three groups (Red, Yellow, Blue), which emerge from the CH. VI) MICRO-SPECTROSCOPE AND POLARISCOPE. 127 prism, the red being least and the blue most bent toward the base of the flint prism(see Fig. 118). Hinge.—The hinge on which the prism tube turns when it is swung off theocular. Ocular (\ 179) —The ocular in which the slit mechanism takes the place of thediaphragm (\ 189). The eye-lens is movable as in a micrometer ocular, so thatthe slit may be accurately focused for the different colors (\ 1

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