A practical treatise on the use of the microscope, including the different methods of preparing and examining animal, vegetable, and mineral structures (1848)
Quekett, John, 1815-1861 · London, H. Bailliere · leaf 263
222 USE OF THE MICROSCOPE. employing two double refracting crystals, placed one over theother, and by removing the NicoPs prism, but retaining thebrass plate on the stage; two distinct images will then be Fig. 139. seen, but at twice the original distance from each other. Ifthe crystal nearest the… … Fig. 140. lution, four images will be equally luminous, and when thecrystal has turned round 90°, there will be only two images ofequal brightness; continuing the turn, two other faint imageswill appear; further on, four images of equal brightness, andat 180° they will all coalesce into one bright…
Microscopy
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