Experimental science. Elementary, practical and experimental physics (1890)
Hopkins, George M. (George Milton), 1842-1902 · New York, Munn & co. · leaf 357
consist of paper or … metal. Paper answers well, and costs nothing. The internaldiameter of the tube is determined by the diameter of the PHOTOGRAPHY. 335 lenses. Ordinary meniscus spectacle lenses of eight inchfocus are employed. These lenses are secured in placeby paper rings, shown at 3, the inner rings being glued…
Physics · Lantern projection · Electric apparatus and appliances
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