. The Bell System technical journal . laced next to the arc lamp is a fixtxl diaphragm and then a smallprojection lens which is corrected chromatically and spherically andbrings the image of the positi\e carbon of the arc lamp to a focus onthe adjustable slit. The slit is provided with a drum bearing a divisions of the scale embrace 50 parts and a complete revolutionof the drum opens the slit ,j mm. so that each division of the scaleadvances the slit l/lOO mm. The slit is fitted with two jaws at right 122 BELL SYSTEM TECHNICAL JOURNAL angles to the principal slit, one being adjustabl
. The Bell System technical journal . laced next to the arc lamp is a fixtxl diaphragm and then a smallprojection lens which is corrected chromatically and spherically andbrings the image of the positi\e carbon of the arc lamp to a focus onthe adjustable slit. The slit is provided with a drum bearing a divisions of the scale embrace 50 parts and a complete revolutionof the drum opens the slit ,j mm. so that each division of the scaleadvances the slit l/lOO mm. The slit is fitted with two jaws at right 122 BELL SYSTEM TECHNICAL JOURNAL angles to the principal slit, one being adjustable by a milled screw function of these jaws is to limit the length of the slit. The slithead may be gi\en a quarter turn so that it may be set horizontally orvertically, which is necessiiry in order to calibrate the instrument asexplained later. A projection lens next in order toward the micro-scope projects the image of the slit into the image plane of a hori-zontally mounted objective which is mounted on a stand witii cross. Fig. 22—Ccllb ■il for ilu- of lliijils willi llie slides so that the objective which serves as an illuminator nia\ bemoved horizontally in two directions, at rigiit angles to each mo\-enient of the cross slides is controlled by screw adjustmentbut for coarse adjustment in the direction of the illuminating train asliding sleeve adjustment is made. By this means the illuminatingobjective can be centered with respect to the obser\ing microscopeobjective. In the correct position the front lens of the illuminatingobjective is about 1 mm. from the mount of the obser\ing objecti\ Biltz cell has a rectangular cross section which permits ofaccurately adjusting the cell in position. A thistle funnel at oneend is for the reception of the liquids; the other end is providedwith a piece of rubber tubing which has a pinchcock to pre\ent theescape of the fluid. The rectangular section of the cell has two quartzwindows
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
