by librefan4ever - uploaded on February 17, 2015, 3:28 pm
Vectorized Duck-Rabbit optical illusion.
Source: Jastrow, J. (1899). The mind's eye. Popular Science Monthly, 54, 299-312.
This media file is in the public domain in the United States. This applies to U.S. works where the copyright has expired, often because its first publication occurred prior to January 1, 1923