A microscope is an optical instrument that uses one or more lenses to produce a magnified image of objects too small to be seen clearly with the naked eye. Antique examples range from simple single-lens instruments to compound microscopes, in which an objective lens and an eyepiece work together, usually mounted on a brass stand with a stage, focusing mechanism and mirror to light the specimen.
The compound microscope emerged in the Netherlands around 1600, and in the seventeenth century Antoni van Leeuwenhoek's tiny single-lens instruments and Robert Hooke's Micrographia of 1665 revealed a previously unseen world. English makers led the field in the eighteenth century, producing elegant instruments in brass, wood, shagreen and vellum, such as the Culpeper type on its tripod of scrolled legs. Improvements in achromatic lenses during the nineteenth century turned the microscope into a serious scientific tool, and leading London makers included Powell and Lealand, Andrew Ross and Smith and Beck. Victorian microscopes were often supplied in fitted mahogany cases with accessories such as extra objectives, live boxes and prepared slides. Collectors look for a maker's signature, completeness, original lacquer and a case that belongs to the instrument, together with sound optics and smooth focusing.
