. The microscope and its revelations. 2S1.—Sorliys inoilificjitifiii oflllc ivtlrrtor. way when not required, as shown in the figure. Dr. Sorlty was able to get results in the examination of polishedsections of steel not otherwise attainable. No opaque illumination,however, has yel surpassed the venerable Lieberkiihn ; the besl experts freely admit thai the finest critical 1(1 be obtained by this met hod of illumination are secured be LieberUiihn. This mode of illuminating opaque objects is b\ means of a > concave speculum reflecting directlv down upon i a focus the
. The microscope and its revelations. 2S1.—Sorliys inoilificjitifiii oflllc ivtlrrtor. way when not required, as shown in the figure. Dr. Sorlty was able to get results in the examination of polishedsections of steel not otherwise attainable. No opaque illumination,however, has yel surpassed the venerable Lieberkiihn ; the besl experts freely admit thai the finest critical 1(1 be obtained by this met hod of illumination are secured be LieberUiihn. This mode of illuminating opaque objects is b\ means of a > concave speculum reflecting directlv down upon i a focus the light reflected up to it from the mirror ; it was. LIEBERKUHN—ITS DRAWBACKS 335 formerly much in use, but is now comparatively seldom concave speculum, termed a Lieberkiilm, from the celebratedmicroscopist who invented it, is made to tit upon the end of theobjective, having a perforation in its centre for the passage of therays from the object to the lens; and in order that it may receiveits light from a mirror beneath (fig. 282, A), the object must be somounted as only to stop out the central portion of the rays that arereflected upwards. The curvature of the speculum is so adapted tothe focus of the objective that, when the latter is duly adjusted, therays reflected up to it from the mirror shall be made to convergestrongly upon the part of the object that is in focus; a separatespeculum is consequently required for every objective. It has two manifest drawbacks: the first one, that of requiri m/ useparate Lieberkilhn for each objective, is a difficulty which in thenature of things cannot be overcome. The radius of t
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
