Varley stirrup lever type microscope, c 1850.

Made by Powell and Lealand, London, this is an improved form of the microscope devised by Cornelius Varley in 1831 and originally made for him by Hugh Powell. It was designed for following the movements of living aquatic objects, its special feature being the stirrup-lever stage which enabled lateral motion to be effected in any direction and the object kept continually under observation.