VERRES PRISMATIQUES & LENTICULAIRES

DISTRIBUTEURS DE LUMIÈRE · L'ÉCLAIRAGE DES LOCAUX OBSCURS
(DISTRIBUTORS OF LIGHT · THE ILLUMINATION OF DARK PLACES)

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Face des prismes (Prismatic face)	Quel verre doit-on choisir ? — celui-ci !!! (Which glass should we choose? — this one!!!)	Face des lentilles (Lenticular face)

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History:

Société Continentale du Verre-Soleil was founded c.1900 to commercialize Moffat and Dobbins' 1899 US patent No. 637,145, Light-Projecting Glass. The patent states:

Our invention relates to that class of light-projecting glasses which have upon one side a series of parallel prism-bars for refracting or reflecting the light, the object of our invention being to so construct such a light-projecting glass that the field from which the same receives its light will be enlarged and greater diffusion of the light effected, so as to materially increase the area to which light supplied by the glass. ... The purpose of such lens-bars is to materially increase the effective area of the source from which the glass derives its illumination, lateral rays being caught and transmitted by the convex surfaces of the lens-bars, which would be lost by reflection from a flat surface or from a glass presenting a considerable area of flat surface on the light-receiving side, all of the rays, moreover, being refracted by the lens without that interference with each other which is an objection to light-projecting glasses in which some of the light is transmitted directly, while other rays are refracted and reflected across the path of the direct rays, thus causing interference which materially detracts from the light-projecting properties of the glass. The lens-bars also serve to cause lateral diffusion of the light projected by the glass, and thereby correspondingly increase the area which can be effectively illuminated.

After the 17-year patent expired in the US, the American 3-Way Prism Company began selling tiles of the same design, called "Lens Back" (see 1915 Sweet's Catalogue of Building Construction). The tiles were intended for use in situations where the daytime sky was obstructed, to collect more light from the sides in compensation.

FIG 1. ACTION OF LIGHT RAYS THROUGH PRISM GLASS Upper section is horizontal through a flat back tile prism; lower is horizontal through a lens back tile prism. Heavy dotted line in both drawn at forty degrees to the surface of the glass. Light rays (dot and dash lines) striking flat back prism at an angle less than forty degrees are reflected off and lost; but if striking a lens back tile, enter the glass and are so refracted that they enter the room and add to illumination. Light rays striking surface of glass at any angle greater than forty degrees (solid lines) enter the glass in both prisms; but light entering lens back prism is broken up and diffused in all directions, as shown.

Marks:

MARQUE DÉPOSÉE

Nº 8940 26 février 1910 SOCIÉTÉ CONTINENTALE DU VERRE‑SOLEIL 7, rue Louis-le-Grand, PARIS (France) VERRE SOLEIL Verres distributeurs de lumière pour toutes applications et notamment pour verres à vitres. Enregistrée en France le 18 décembre 1909. Les marques internationales

MARQUE DÉPOSÉE