An unusual late 18th century pocket folding microscope. This design was invented by William Withering.
 It consists of a wooden case which when opened automatically erects the microscope from the case. This type is known as the Withering botanical microscope. Originally the case would also have contained tweezers, needle maybe a scalpel. 
The stage and single magnifying lens is attached to the support rods via pins. This allows the microscope to unfold from its flat storage condition to a stacked, open position. The Withering folding microscope had at least four different arrangements. The first had three support rods  Subsequent microscopes had only one support rod to give easier access to the sample stage. All folded the stage and lens automaticallywhen the case was closed. 
 
These pocket microscopes were popular at the time both men and ladies taking a keen interest in nature would carry them in their pockets on their travels. Now difficult to find.
 
It measures 12cm l x 6.4cm d x 2.7cm h when closed.