Carpenter, William Benjamin, 1813-1885, Dallinger, W. H. (William Henry), 1842-1909 · Philadelphia, Blakiston · leaf 353
diaphragm being in>focus.1 Another negative eye-piece is that known as the Keiiner, ororthoscope. This consists of a bi-convex field-glass, and an achromatic,doublet meniscus (bi-convex and bi-concave) eye-lens. A verticalsection of one so constructed is seen in fig. 279. These eye-piecesusually…
Microscopy
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![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten20unit-853-387.webp)
