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247,996 · Pennycuick · "Tile for Illuminating Purposes" · Page 2 Home  > Prism Glass  > Patent Index  > Page 2

247,996: 2 of 3

For particular situations the lenses may be plain or corrugated, waved or angular on the reflecting-surface, and they may be coated with sterling silver or other reflecting substance.     I am aware that pyramidal lenses have been used; but they concentrate the light too much and diffuse it too little. They decrease instead of increasing the quantity of light admitted, while mine greatly augment the light which would naturally come through a given aperture.     What I claim as new and of my invention is--     1. The semi-prism B, raised at the center and

provided with radial grooves and beveled sides b, whereby the radiating-surface is augmented and protected from abrasion, as described.     2. The central spur, c, projecting up above said face, in combination with projections d on the lens-frame, as and for the purpose set forth.     3. The semi-prism B, having its downwardly-extending tongues inclined on the back face, f, as and for the purpose specified. JAMES G. PENNYCUICK. Witnesses:     GEO. D. WALKER,     C. SEDGWICK