Stamp, in blue ink, on verso, lower left: H.E. EDGERTON | M.I.T. 4-405 | CAMBRIDGE-MASS. Stamp, in black ink, on verso, lower left: [stamp is in box shape with two palm trees on left side] © 19 Estate of | 10.639 [in pencil] | HAROLD E. EDGERTON.
Inscribed, in pencil, on verso, upper right corner: 10.639 [boxed].