The microscope and its revelations . Smith and Becks Achiomatic Condenser. ACHEOilATIC COXDEXSER.—EEFLECTIX& PKISIMS. 127 hoiir and minute-hands of a Tvatch), by means of a secondmilled-head, numbered at its edge like the first; and theapertures in the diaphi-agm-plate being simple circles, the Fig. Powell and Lealands Achromatic Condenser. centres of these are covered by stops of different sizes, sup-plied by the second or ; by which very ingeniousarran2:ement, a great variety of combinations may be obtained,aU of them indicated by the numberm^ on the two Refl
The microscope and its revelations . Smith and Becks Achiomatic Condenser. ACHEOilATIC COXDEXSER.—EEFLECTIX& PKISIMS. 127 hoiir and minute-hands of a Tvatch), by means of a secondmilled-head, numbered at its edge like the first; and theapertures in the diaphi-agm-plate being simple circles, the Fig. Powell and Lealands Achromatic Condenser. centres of these are covered by stops of different sizes, sup-plied by the second or ; by which very ingeniousarran2:ement, a great variety of combinations may be obtained,aU of them indicated by the numberm^ on the two Reflectiiig Prisms.—Every mirror composed of glasssilvered at the back, gives, as is well known, a_ double reflec-tion ; namely, a principal image from the metallic surface, anda secondaiT image from the surface of the glass in front of secondary image, it has been thought, interferes ^viththe perfect performance of the achiomatic condenser: andhence for obtaining the most satisfactory definition, some^Microscopists prefer to dii-ect the axis of the microscope tothe souice of light (the mirror being tuimed aside); whilstothers feehno- the inconvenience of the position thus requhed,have recouise to a prism which shall give the required refiec-tion ^vith only a single miage. The prism usually
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Keywords: ., bookcentury1800, booksubjectmicroscopes, booksubjectmicroscopy
