n.p. Self-published by the author, ca. 1939. Broadside. A single giant folio leaf folded once to make a 14x11 inch brochure with blank interior surfaces. Outwardly, one of the exterior surfaces is a vivid color representation of the 25-ton "sun stone", the other surface is an explanatory diagram in two colors. Display could emphasize one or the other image -or both, side by side. A very good clean copy.