CoFophonia melted; and if you will make Convex Spectacles, you must have a hollow iron dish, that is a portion of a great Sphaere, as you will have your Spectacles more or less Convex; and the dish must be perfectly polished. But if we seek for Concave...
Descartes and the Hyperbolic Quest: Lens Making Machines and Their ... - Page 12
by D. Graham Burnett - 2005 - 152 pages
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