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Knight's Mechanical Encyclopedia (ed. Knight) 2 0 Browse Search
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e of glass, from 1/20 to 1/50 of an inch in diameter. Having made and polished his lens, he placed it against a small hole in a thin piece of metal and fixed it with wax. Leuwenhoeck's microscopes, 26 in number, which he presented to the Royal Society, have each a doubleconvex lens. Their powers were from 40 to 160. Comes Mr. Reeve, with a microscope and a scotoscope. For the first I did give him £ 5 10 s., a great price, but a most curious bawble it is. — Pepys's Diary, 1664. Stephen Gray's poor-man's microscope, 1696, was merely a drop of water suspended at the end of a wire or pin. A piece of perforated cardboard or sheet-metal affords a better means of holding the drop of water, whose rounded surfaces give it the properties of a lens. By fusing in the flame of a spirit-lamp a small piece of glass contained within a ring of platinumwire, a lens may be formed. A piece of the wire should project, so as to form a handle. Plate-glass is the material commonly used for