'THE PROJECTION EYEPIECE':

The projection eyepiece is of the smaller standard 0.9173 inch diameter. It is signed 'W. Watson & Sons Ltd.,London' on the brass disk. Adapters were readily available for use with the older large diameter draw tubes. It has a nickel-plated body, lacquered brass scale and flat black top aperture. the aperture on top of relatively small diameter and can be removed. The brass scale provides calibrated focusing. It was designed to be used with any objective including apochromatics, and must have been popular as it was offered from the late 19th century into the 1930's. It was offered after 1885, not being found in the 1885 catalog, but found from 1893 onward.

Thanks to Dr. Joe Zeligs for the catalog dating