A fabulous example of a powerful Coddington Magnifying glass dating to around 1900.
A Coddington magnifier is a magnifying glass consisting of a single very thick lens with a central deep groove diaphragm at the equator, thus limiting the rays to those close to the axis, which again minimizes spherical aberration. This allows for greater magnification than a conventional magnifying glass, typically 10× up to 20×. Most single lens magnifiers are limited to 5× or so before significant distortion occurs. The drawback is that the diaphragm groove reduces the area seen through the magnifier.
Excellent condition measuring 1 1/2" in diameter x 1 5/8" tall; spanning 4" in length including the handle.