Original unsigned pencil sketch of a two lamp tube on an off-white, lightly-lined 8.5 x 11 sheet. Labeled along the top, 'Working drawing, June 6/27, 2 Lamp Tube.' Sketch depicts ear phones on the right, and a 'Bell mike' on the left, with a system of resistors, batteries and vacuum tubes in between. Even overall toning to sheet and two punch holes to left edge, otherwise fine condition. COA John Reznikoff/University Archives and RRAuction COA.
