. The microscope and its revelations. FIG. 349.—Condenser and object-glass with the same aperture. FIG, 350.—The same, with the apertureof the condenser cut down. and it is /•// I/ml ulmn Unit n critinil />i<tnre can be found. If thecondenser he racked either within or without the focus, the wliol?Inl,I /rill Ixi-onii illnniiiii/lr,/. hut, a,t the same time a far smaller por-tion of the objective will be utilised. On removing the eye-piece andexamining 1 lie hack lens of t he object ive. pict nres like I), H, fig. 34.).will be seen I) when within, and II when without the focus. The condi
. The microscope and its revelations. FIG. 349.—Condenser and object-glass with the same aperture. FIG, 350.—The same, with the apertureof the condenser cut down. and it is /•// I/ml ulmn Unit n critinil />i<tnre can be found. If thecondenser he racked either within or without the focus, the wliol?Inl,I /rill Ixi-onii illnniiiii/lr,/. hut, a,t the same time a far smaller por-tion of the objective will be utilised. On removing the eye-piece andexamining 1 lie hack lens of t he object ive. pict nres like I), H, fig. 34.).will be seen I) when within, and II when without the focus. The condition represented in fig. 349 at R and (_) is the severesttest which can be applied to the microscopic objective; that is tosay, to fill the whole objective \viih light and so test the marginal Hiil i-iiiti-iil /xif/iniiN ill tin MI mi linn. Kven to obtain the state of illumination known as diffused day-. WEH HEH EH O z s H O H TO USE DIFFUSED DAYLIGHT 411 light with the simple mirror when no condenser is used is frequentlyclone in a most inaccurate manner. The correct method of doingthis is shown in fig. 351. F is the plane of the object, C is the con-cave mirror, the mirror being placed at the distance of its principalfocus from the object. But the manner in which it is usually done,from want of thought or knowledge, or both, is shown in fig. .••> 2.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
