. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. aratusin front of the polariser is the same as that of the front partof the apparatus shown in fig. 194. The stage apertureshould be made large enough to take quite a thick woodenframe, with another frame containing a quarter-wave plate oran even film : sometimes the instrument is made with aseparate aperture or stage for a quarter-wave plate, betweenthe ordinary working stage and the polariser. The crystalapparatus can all be removed or added in a few seconds, andI prefer the analyser mount
. Optical projection : a treatise on the use of the lantern in exhibition and scientific demonstration. aratusin front of the polariser is the same as that of the front partof the apparatus shown in fig. 194. The stage apertureshould be made large enough to take quite a thick woodenframe, with another frame containing a quarter-wave plate oran even film : sometimes the instrument is made with aseparate aperture or stage for a quarter-wave plate, betweenthe ordinary working stage and the polariser. The crystalapparatus can all be removed or added in a few seconds, andI prefer the analyser mounted with differently-sized collars atthe two ends, one of which fits the nozzle of f for ordinarywork, and the other of which, when pushed in, can be adjustedto the proper position for crystal-ring projections to passthrough it. A quarter-wave plate can be inserted if necessary LANTERN POLARISING APPARATUS 343 Tl t^^-* H O O W <w tn rt a) -r* H a -a t- . — ... rti .^ =1= 60 08 lj ^osce^.oj^a^-gs^iojosg* ffl aft- S 03^: I, §53 £^-9 .shops «?§ll^ J!! g ^la^^t^1 1=1= a g«gjafl g^Ss« a ss M,3.
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Keywords: ., bookauthorwrightle, bookcentury1900, bookdecade1900, bookyear1906
