The microscope : its construction and management : including technique, photo-micrography, and the past and future of the microscope (1893)
Heurck, Henri van, 1838-1909 · London : C. Lockwood ; New York : D. Van Nostrand Co. · leaf 250
here is, WATSON AND SONS. 229 therefore, every possible length that can be desired for the correction ofapochromatic objectives, made either for the Continental or English lengthof tube. The innermost tube is the narrowest in the upper part, so that itcan be blackened internally over half the space… … 230 WATSON AND SONS. The lower end of the draw tube is provided with the Society screwfor use with the Abbe apertometer, &c.
Microscopy
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