The "solar microscope" is a image projection magnifier designed to be bolted to a shutter or window, with the mirror (missing in this specimen) facing toward the sun. Thumb screws adjust the angle and inclination to project sunlight through the condenser lens and barrel, into one of three optical devices:

1. High-magnification, transmitted light (shown)
2. Low-magnification, transmitted light
3. Low-magnification, epi-illumination

This instrument is unsigned, but is undoubtedly English and was manufactured in the late 18th Century.

Accessories consist of brass forceps, two glass phials, and a brass plunger device of unknown function