Back cover illustration by Henry Holiday to Lewis Carroll’s tragicomical poem The Hunting of the Snark (1876) with a detail rendered in four variations: (1) original, (2) vertically flipped, (3) horizontally flipped, (4) rotated by 180°.
I don’t know whether these patterns are letters. If so, they could be asemic. If not, could they be read as e.g. “Anne I”? Who knows? But the pattern in that detail is distinctively different from its surrounding.
More about the back cover illustration: When the queen met the Boojum:
2017-09-08, update: 2023-01-18