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627,848: 1 of 3

Patents: 490 of 530	UNITED STATES PATENT OFFICE. GODFREY FUGMAN, OF CLEVELAND, OHIO.	Godfrey Fugman 1 of 1
GLASS PRISM-PLATE. SPECIFICATION forming part of Letter Patent No. 627,848, dated June 27, 1899. Application filed July 15, 1898. Serial No. 685,991. (No model.)

To all whom it may concern:     Be it known that I, GODFREY FUGMAN, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Glass Prism-Plates, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings.     The invention relates to a glass plate adapted for use as a window-glass or for some analogous purpose, the object being to refract large quantities of brilliant light into interiors in the most useful direction.     The invention consists of a glass plate having one side made up of a plurality of rows of angular-faced prismatic lugs which are shaped and arranged substantially as shown in the drawings and as hereinafter described.     In the drawings, Figure 1 is a rear view of the glass prism-plate embodying my invention. Fig. 2 is a vertical sectional view on line 2 2 of Fig. 1. Fig. 2a is a view of the angular refracting-face of one of the lugs shown in Fig. 1. Fig. 3 is a rear view, and Fig. 4 is a sectional side view, of a modified form of the invention. Fig. 4a is a view of the angular refracting-face of one of the lugs shown in Fig. 3. Figs. 5 and 6 are respectively a rear view and a sectional side view of another modified form of the invention, and Fig. 6a is a view of an angular refracting-face of one of the lugs shown in Fig. 5. Figs. 7 and 8 are respectively a rear view and a sectional side view of another modified form of the invention, and Figs. 8a and 8b are respectively views of the angular refracting-faces of the two forms of lugs shown in Fig. 7.     The front side a of the glass plate is preferably plane. The rear side is made up of a plurality of angular-faced projecting prismatic lugs B C D, &c., which are arranged in horizontal rows. The lugs in each row are staggered with respect to the lugs in the rows above and below them. Each lug extends past the adjacent lugs in the rows above and below it for about half their length—that is to say, the top of any lug lies substantially midway between the top and bottom of the adjacent lugs in the row above it, and the bottom of said lug is about midway between the top and bottom of the adjacent lugs in the

row below it. The sides of each lug are so shaped that they fit against the sides of the adjacent lugs in the rows above and below it.     The top faces b, c, and d of the lugs are preferably at right angles, or nearly so, to the general plane of the plate. All of said top faces in any row are in the same plane, and all of said planes are preferably parallel.     The refracting-faces b' b² c' c², &c., of the lugs in the several rows are respectively placed substantially as follows, to wit: All of said faces in any row are in the same plane, and the several planes containing the refracting-faces of the lugs in different rows are parallel to each other and lie at an angle of thirty-five degrees, more or less, to the general plane of the glass plate. The different uses to which the plate is adapted may render it desirable to form these refracting-faces at other angles to the general plane of the plate, as will be understood by those familiar with the art. These oblique refracting-faces of the lugs are widest at their tops and bottoms and grow symmetrically narrower toward a line midway between said tops and bottoms. It is because of this form that the sides of each lug are adapted to match and contact with the sides of adjacent lugs in the rows above and below it. The glass plate has preferably a plain marginal edge a² on all sides to facilitate securing it in a suitable frame.     It will be noticed that in the described plate the total area of the refracting-surfaces is very large, being, in fact, larger than the area of the flat surface of the plate on the front side thereof. It will further be noticed that there are no long grooves extending in any direction across the plate. Such grooves have heretofore been characteristic of all prism-plates wherein the total area of the refracting-surfaces is large and wherein said refracting-surfaces lie in parallel planes at an angle to the plane of the front face of the plate, and it is desirable that in all prism-plates which are intended for refracting light through a single opening into a dark interior these refracting-surfaces shall be in parallel planes. These long grooves are objectionable for several reasons. In the first place, they cause the refracted light to be divided by long dark streaks. The principal objection, however, is that they weaken the plate, and