shallow or of such a considerable radius of curvature that an incident ray striking any part of the curved surface of the lens-bar and refracted thereby cannot reach any internal surface of the lens-bar so as to be reflected, but will, after refraction, pass directly through the glass until it reaches the opposite prism-surface.

One of the advantages of a light-projecting glass constructed in accordance with our invention is that it may be used effectively in the manner shown; that is to say, occupying a relation in respect to the upper portion of the window opening which is the reverse of the usual awning or canopy position, thereby permitting the direct transmission of light through the upper portion of the window-opening in addition to that which is projected therethrough by the glass, thus insuring the lighting of an area close to the window and overcoming a defect in prism glasses as ordinarily used, which rob the areas near the window-openings of light for the benefit of the portions to which the latter is projected.

We may state that one of the incidental advantages of our invention is that the lens-bare very materially increase the strength of the glass and permit us to produce glasses of larger area than is possible in making light-projecting glasses of ordinary character.

Having now particularly described and ascertained the nature of our said invention, and in what manner the same is to be performed, we declare that what we claim is: