Abel Chapman 1851-1929. Ink & wash drawing for his book Savage Sudan (London, 1921), ca. 1913-20.From the Smithsonian: “While sketching zebras in Sudan, the British hunter-naturalist Abel Chapman noted that his perception of stripe patterns could change. Depending on distance and the angle of light, a zebra’s stripes could even seem to disappear.” Scan of 2 d image in the public domain believed to be free to use without restriction in the US.