Be it known that I, EDWARD J. DOBBINS, a citizen of the United States, residing at Neshaminy, Bucks county, Pennsylvania, have invented and produced a new and useful Design for Prism-Plates, of which the following is a specification.

Figure 1 is a plan view of a prism plate embodying my new design.

Figure 2 is a sectional elevation taken on the line 2 2 of Figure 1.

Figure 3 is a sectional elevation taken on the line 3 3 of Figure 1.

As shown in the drawings, the leading or material feature of my design consists in a series of parallel prismatic ribs on one side of the plate, and a second or independent series of parallel prismatic ribs formed on the other side of the plate, the ribs on one side of the plate extending across, or, so to speak, transversely with respect to, the ribs on the other side of the plate.

The ribs on one side of the plate a, to-wit, those designated b, are of approximately A-shaped section.

The ribs c, on the other side of the plate, have concave side faces, the surfaces of the longitudinally-extending concave spaces between the apices of adjacent ribs being in section in the form of arcs of circles.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is—

The design for a prism plate, as herein shown and described.

In testimony that I claim the foregoing as my invention I have hereunto signed my name this 31st day of March, A.D. 1900.

In presence of—

G. A. SCHWAB,

F. NORMAN DINON.