. The microscope and its revelations. FIG. 78.—Stephensons erectingbinocular (1870). 102 VISKN VTITH THE COMPOUND MICROSCOPE Pi P2 A form of this binocular eye-piece was made by Professor Abbewith the intimity and thoroughness characteristic of the firm ofZeiss; but in spite of its beauty as an optical instrument, and its use-fulness as applicable to any tube, and especially the shorter tubesto which tin- \Venhambinocular could not well:i]ply. the doulilc imagein the right-hand tubewas most conspicuouslyapparent, greatly inter-fering \\ itli the perfectionof the .stereoscopic this acc
. The microscope and its revelations. FIG. 78.—Stephensons erectingbinocular (1870). 102 VISKN VTITH THE COMPOUND MICROSCOPE Pi P2 A form of this binocular eye-piece was made by Professor Abbewith the intimity and thoroughness characteristic of the firm ofZeiss; but in spite of its beauty as an optical instrument, and its use-fulness as applicable to any tube, and especially the shorter tubesto which tin- \Venhambinocular could not well:i]ply. the doulilc imagein the right-hand tubewas most conspicuouslyapparent, greatly inter-fering \\ itli the perfectionof the .stereoscopic this account chiefly ithas not come into generaluse. \V e a re neverthelessindebted to the firm ofZeiss for the introductionof a very satisfactoryform of binocular instru-ment, of which we canspeak with unconditionalpraise. It is designatedas Greenoughs binocularmicroscope, and we canconfidently affirm thatit furnishes an accuratesolid and withal an erectimage, so that for all the T. Ih,. 79.— < s binomial1 microscope (1897). purposes for \\ hich the use of the binocular is at present desirable it ac-uliat is Bought, and will be found invaluable for zoologists. botanists, and enilu-yologists. The microscope is shown in fig. 79, GEEENOUGHS BINOCULAR 3IICKOSOOPE IO- II ill! and has been constructed by means of a combination of Porro prismswith a compound microscope of the usual optical type ; it possessesmany of the advantages of the compound micro-scope, but inevitably loses light by the passing ofthe ray through so many prisms, yet by means ofthe Porro prisms the inverted image is renderederect. This may be practically illustrated by , which shows that the rays of light in passingfrom the object to the eye undergo four succes-sive reflexions at the surfaces of the prisms andemerge from the last prism with undiminishedintensity. The prisms, it will be seen, have theeffect of erecting the inverted image formedby the object-glass. But in this microscopebin
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
