Carpenter, William Benjamin, 1813-1885, Dallinger, W. H. (William Henry), 1842-1909 · Philadelphia, Blakiston · leaf 282
Fig. 200.—Powell and Lealands new low-power condenser. This combination consists of aduplex front with two doublet backs ; it is nearly of the same poweras their dry achromatic condenser, but is of much greater aperture.It lias been brought still more recently to a very high state of per-
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