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Patents: 295 of 530	UNITED STATES PATENT OFFICE. JOHN R. RUSSEL, OF DETROIT, MICHIGAN. DESIGN FOR A PRISM-BLOCK.
SPECIFICATION forming part of Design No. 26,828, dated March 30, 1897. Application filed January 30, 1897. Serial No. 621,360. Term of patent 14 years.

To all whom it may concern:     Be it known that I, JOHN R. RUSSEL, a citizen of the United States, residing in Detroit, county of Wayne, State of Michigan, have invented and produced a new and original design for Prisms for Area-Lighting, of which the following is a specification, reference being had to the accompanying drawings, which form a part thereof.     Figure 1 is a perspective view of my newly-designed prism-block for area-lighting. Fig. 2 is a side elevation.     A indicates the prism-block, which is rectangular on the top surface, and from the top surface downward has four rectangular sides, which drop vertically or nearly vertically downward. Beneath these vertical sides there extends inward a horizontal flange or table at each side and at each end of the block. From the lower surface there depend triangular prism-blocks, each of which has its lower trihedral angle a substantially right angle, but the two oblique faces of the triangular prism are of uneven length in extent from the trihedral angle to the lower face a of the prism-block, so that the end surface of each of the

prisms presents the appearance of the right-angle triangle of which the hypotenuse is along the lower face a of the prism block, and the two sides about the right angle are unequal in length.     All of the several prisms in the block are exactly similar and similarly placed.     In Fig. 2 the lines b c, c d, d e indicate the several hypotenuses of the right-angle triangles. The lines b f, c g, d h indicate the short lines adjacent to the right angles.     The characteristic features of my design consist, essentially, in the flat top surface of the several prisms and the converging lower side surfaces thereof, which in each prism are of different length.     What I claim--     The design for a prism-block, substantially as herein shown and described.     In testimony whereof I sign this specification in the presence of two witnesses. JOHN R. RUSSEL. Witnesses:     ARTHUR T. WATERFALL,     RICHARD BATESON.