Name/Title
EtchingEntry/Object ID
85.15.72Description
Etching: A square composed of nine smaller squares, each marked with a number (1/4, 1/2, 1, 2, 4, 8, 15, 22 1/2, 30) in a circle in upper left corner. Squares show change in darkness, "1/4" being the lightest, and "30" being the darkest square. Below pattern is inscription and signature. First proof.