How Eyeglasses Are Made

The pieces of glass which are to be made into lenses f or spectacles, Lor microscopes, small telescopes and the like are tirst ground into shape, roughly, by )eing held against a cast iron tooi like a grindstone. This of course is curved ;o give the lens the concavity or convexity desired. From this tooi the glass jasses to a "fine tooi," so called, of simiar construction, but made of brass and covered with a fine powder of sulphate of iron. calcined and gronnd. Jewelers cali it rouge. Then a third tooi, like the second, but covered with cloth whïch is thoroughly powdered with rouge, is used for polishing. After both sides ïave been treated thus the lens is cut to the required shape, oval or round, with a diamond glass cutter and steel pincers, and the edges are ground smooth on metal wheels.