Public Domain Mark
You can use this work for any purpose without restriction under copyright law. Read more about this licence.
Credit
An eye in a star, the spokes of which divide the spectrum of colours; putti hold a prism, a telescope, a rod refracted in water, and a camera obscura; representing optics. Engraving by J. Chapman, 1820, after A.D. Macquin. Public Domain Mark. Source: Wellcome Collection.