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This manner of fastening the glass and inserting it from below, enables us to use the projecting "illuminating lens" a, as also the "double convex" lens b, and to get such an extension and mass of the glass below the plate as to give with the "double convex" lens (b) three times the light of the ordinary bull's eye lens, and with the "illuminating lens" (a) to give a flood of light and send it to the back of a deep basement.   In all the other varieties of projecting lenses now in the market, the glass being inserted from the top, cannot be enlarged below the plate, and being fastened only by a shallow bed of cement, the work cannot be shipped, handled nor cleaned without loosening a large