Silver gelatin print. Image depicts John Thomas, Secretary/Treasurer of Corning Glassworks in front of the back of the disk cast by Corning for the Hale Reflecting Telescope of Mount Polomar, CA. The disk is 200 inches in diameter, 26 inches thick, and weighs 20 tons. During manufacture, the furnace was so hot that several cores in the brick mold broke away from the metal anchor rods and floated on top of the molten glass. Though the resulting disk was unusable, it was used to test the annealing process for pouring the second disk. The first disk is on display in Corning, New York. in simple wood frame. Image 7-1/2" x 9-1/2". Overall in frame 12-1/2" x 17-3/4".