DESCRIPTION: This 'Aplanatic Magnifier' with a Magnification of 20 power, is signed:

'W. WATSON & SONS, LONDON' and on the top: '20'

The original turned wooden case is unsigned. The form is a cylinder without a handle. The instrument is made of nickel-plated brass with the ends made of blackened brass and knurled. As is mentioned in the catalog (entry shown here), the instrument produces a flat field from edge to edge, but for proper use, it must be held close to the eye. The fact that a flat object that is being viewed is in focus from edge to edge is what makes this instrument 'aplanatic' which means free of spherical aberration. This instrument does offer fine flat images from edge to edge.

HISTORY OF THIS LOUPE

This magnifier is very similar in appearance to the Zeiss magnifier on this site, although this is a much higher power loupe. Watson catalogs reveal these were offered from no later than 1893 through at least 1924. The optical design is quite similar to the Zeiss version, as is the device itself, and even its turned wooden case. The Zeiss version was offered from about 1891.