This is a microscopic magnifier designed for testing linen and counting thread. It is a prototype with the patent number and inventor’s name. It has a switch to turn on two torch light bulbs and was powered by two dry cell batteries, we removed the batteries. Probably 1920’s based on the box work and torch light bulbs. The microscope eyepiece was common from 1850’s on wards. Thread was counted by looking through the eyepiece onto a template with different shapes.
@fr1da Yes, thanks Frida