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 222
he lamp; and rr rr diverging rays of light falling upon OPAQUE OBJECTS. 181 the lens D E; these rays, as also those shown by fig. 100, willbe brought into a focus F, when the lens is placed as thererepresented; but if the flat side occupy the same position,then, according to fig. 101, it will be in… … Fig. 114. rays nearest the margin of the lens D E will be brought toa focus upon the object «, but those nearer the centre willpass on to F, so that a will be only illuminated to about one-half the extent of a in the preceding figure. When, however,it is required to procure either parallel or…
Microscopy
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