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Patents: 220 of 530	UNITED STATES PATENT OFFICE JAMES C. FRENCH, OF BROOKLYN, NEW YORK. PAVEMENT AND FLOOR LIGHT.
SPECIFICATION forming part of Letters Patent No. 394,260, dated December 11, 1888. Application filed June 23, 1888. Serial No. 277,941. (No model.)

To all whom it may concern:     Be it known that I, JAMES C. FRENCH, of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Pavement and Floor Lights, of which the following is a specification.     My invention relates to glazed pavements and floors through which light is admitted to vaults or apartments beneath, and in which pieces of glass called "lenses" are placed upon a cast-iron grating, bed-plate, or frame over openings therein and are bedded in cement thereon.     I will describe in detail a pavement or floor light embodying my improvement, and then point out the novel features in claims.     Figure 1 represents a plan view of a portion of a pavement-light embodying my improvement. Fig. 2 represents a vertical section of same on the line x x of Fig. 1. Fig. 3 represents a face view of a sheet of metal which may be bent into the form of a taper ring or casing for inclosing the elastic cement.     Like letters of reference indicate corresponding parts in all the figures.     A represents a perforated plate or grating for a pavement or floor light suitable for vault, sidewalk, floor, roof, or wherever a light-transmitting pavement or floor may be required.     B indicates the apertures, perforations, or holes through the bed-plate for the downward passage of light. The line x x, being drawn through the centers of adjacent holes or perforations B, is the line of least strength, the metal of the plate between the holes being wider, and consequently stronger, everywhere else than on that or other lines connecting centers of adjacent holes B. To strengthen these weak places of the bed-plate, I form between each hole B and every adjacent hole B over the weak place between the two a strengthening-rib, a, every one of which ribs is isolated from every other one, extending only a short distance on each side of the place it is intended to strengthen. Were the several isolated ribs a extended each way until they met and united at points b, Fig. 1, they would then together constitute continuous and connected ribs of a form in common

use, but which would consist in part of a useless body of metal, considerably increasing the weight without adding to the strength of time weakest parts of the bed-plate.     C are the lenses or pieces of glass covering the holes B. The lenses C have hitherto been made with vertical sides, and therefore liable to be easily loosened or displaced from their bed in the body of cement, D, which cement is represented in the figures as covering a part only of the piece of bed-plate therein represented. To prevent such loosening or displacement of the lenses, I make the lenses C taper or smaller on the top or upper face than on the bottom or lower face. Being tapering, the lenses, if once embedded in the cement, D, cannot be removed without first breaking out and removing a portion of the surrounding cement.     To allow for the expansion and contraction of the lenses in accordance with the changes of temperature to which they may be exposed, I provide a surrounding annular coating, c, of an elastic cement, which may be economically made of a combination of sulphur and coal-tar, and I incase this elastic ring or coating with a ring of thin metal having the same taper as the lenses and as the elastic coating which surrounds them. In order that the body of cement, D, may entirely cover and hide from view the ribs a, the rings or coatings c, and rings or casings d, the lenses C project considerably above the ribs a and a short distance above the tubes c and d. This difference in height between the lenses and tubes may be about one-sixteenth of an inch. If the difference is too much, when an adjacent portion of the cement, D, is dislodged the edges of the glass will be exposed anti liable to injury; if too little, the ends of the tubes will be liable to become exposed to view. To prevent injury to the lenses when an adjacent portion of the cement, D, is dislodged from around it, I taper or bevel the upper outer edges of the lenses toward the center above the tops of the tubes, as represented in the drawings at h. The ribs a serve also to guide the lenses to their seats and retain them thereon before the cement, D, is spread, and they also serve moo to penetrate and hold the cement.     To prepare the pavement or floor light for