The microscope; an introduction to microscopic methods and to histology . hepart measured is y-jj-Q-th mm. x 8 = T-§-y mm. or So ju (§ 166). SeeMark, Jour. Applied Microscopy, Vol. I, p. 4. § 173. Micrometry with the Ocular Micrometer.—Use the 3mm. (-|- in.) objective with the preparation of Necturus blood-corpusclesas object. Make certain that the tube of the microscope is of the samelength as when determining the ocular micrometer valuation. In aword, be sure that all the conditions are exactly as when the valuationwas determined, then put the preparation under the microscope andfind the sam
The microscope; an introduction to microscopic methods and to histology . hepart measured is y-jj-Q-th mm. x 8 = T-§-y mm. or So ju (§ 166). SeeMark, Jour. Applied Microscopy, Vol. I, p. 4. § 173. Micrometry with the Ocular Micrometer.—Use the 3mm. (-|- in.) objective with the preparation of Necturus blood-corpusclesas object. Make certain that the tube of the microscope is of the samelength as when determining the ocular micrometer valuation. In aword, be sure that all the conditions are exactly as when the valuationwas determined, then put the preparation under the microscope andfind the same three red corpuscles that were measured in the otherwaj^s (§168-169). Count the divisions on the ocular micrometer required to encloseor measure the long and the short axis of each of the three corpuscles,multiply the number of spaces in both cases by the valuation of theocular micrometer for this objective, tube-length and ocular, and theresults will represent the actual length of the axes of the corpusclesin each case. CH. IV] MAGNIFICATION AND MICROMETRY 117. The same corpuscle is, of course, of the same actual size, whenmeasured in each of the three ways, so that if the methods are correctand the work carefully enough done, the same results should be ob-tained by each method. (§ 176).* Fig. 106. Ocular Screw-Micrometer withcompensation ocular X 6. The upper figureshows a sectional view of the ocular and thescrew for -moving the micrometer at the the left is shown a clamping screw tofasten the ocular to the upper part of the mi-croscope ticbe. Below is a face view, showingthe graduation on the wheel. An ocularpiicrometer like this is in general like thecob-web micrometer and may be used formeasuring objects of varying sizes very accu-rately. With the ordinary ocular micrometervery small objects frequently fill but a part ofan interval of the micrometer, but with thisthe movable cross lines traverse the object {orrather its real image) regardless of the minu
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