Carpenter, William Benjamin, 1813-1885, Dallinger, W. H. (William Henry), 1842-1909 · Philadelphia, Blakiston · leaf 299
to interpose a plate of selenite between the polariser and the object ;and it is advantageous that this shouldbe made to revolve. A very convenientmode of effecting this is to mount theselenite plate in a revolving collar, whichfits into the upper end of the tube thatreceives the polarising prism.… … Fig. 221. . the revolving collar. A still greater variety may be obtained by mountingthree films, which separately give three different colours, in collarsrevolving in a frame resembling that in which hand-magnifiers areusually mounted, this frame being fitted into the sub-stage in sucha manner…
Microscopy
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