German Goerz Double Image Micrometer Periscopic Range Finder
Halftone reproduction of a diagram of a periscope range finding device described as the latest Goerz double image micrometer range-finder&qupt;. The device uses a split-image to determine the approximate distance to a target. This is Figure 5 of The Science of Low Visibility and Deception as an Aid to the Defense of Vessels Against Attack by Submarines, by Lindell T. Bates. Published by the Submarine Defense Association, New York City, 1918. In 1974 the original volume was in Record Group 45 at the U.S. National Archives. U.S. Naval History and Heritage Command Photograph.