. The microscope and its revelations. ne of its construction and the path of the light-beams is L 146 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE in fig. 1 1 3. It was for examining transparent objects and v,-;is-imilar to the Cassegrainian telescope, but with an extra long eye-piece tube to permit the focussing by movement of the object was placed at M X ; the image was taken up by theconcave, reflected on the convex, and again reflected to the advised the use of a condensing lens for the illumination, to pre-vent the mixture of foreign rays with those of the objec
. The microscope and its revelations. ne of its construction and the path of the light-beams is L 146 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE in fig. 1 1 3. It was for examining transparent objects and v,-;is-imilar to the Cassegrainian telescope, but with an extra long eye-piece tube to permit the focussing by movement of the object was placed at M X ; the image was taken up by theconcave, reflected on the convex, and again reflected to the advised the use of a condensing lens for the illumination, to pre-vent the mixture of foreign rays with those of the object, otherwisethe instrument gave confused images of distant objects when it wasu>cd as a microscope. Kven without a condenser there are good images attainable withthis instrument, but with the condenser they would be, of course,improved. We have not followed in any detail the forms of simple micro-scopes as they presented themselves, but in 1755 a form was made1 iy Cuff that can only be regarded as the precursor of the most com- A-. FIG. ll:j.—Smiths reflecting microscope (1738). plete and perfecl of our simple dissecting microscopes : it is shown A disc of plane glass, C, or a concave, M, was applied, on the stage of which dissections .vr. could be made; a mirror, I, was fitted in a with a stem sliding in a socket in the pillar; the lens-carrier, F, alone, or with Lieberkiihn, F, screwed in a ring on the end of a horizontal arm. E. sliding through a socket, attached to a vertical rod, D, sliding and rotating in a socket at the back of «• pillar for focussing A-c. This motion of the lens over the object :came very popular and was employed in nearly all microscopes up mif f the establishment of achromatism ; the last microscope was that designed b\ Mr. \V. Valentine and made by l11 movement in arc lasted much longer, anil remnant of it is still to be found in Powells No. I. ••1 id of the box. within which the instru- •ked with sundry accessories. he discover
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmicrosc, bookyear1901
