George Adams' 'New Universal Single Microscope' of 1746. The instrument was made of brass or silver, and had six double convex lenses of different focal lengths mounted in a rotating holder, giving six magnifications. These lenses are labelled M. N is an eye cup for viewing, and O is a Lieberkuhn for looking at opaque objects. Focusing was achieved by moving the specimen (on platform I) up and down by means of the screw P at the base of the pillar. F is a mirror for reflecting illumination up through the specimen.