c.1760, English, unsigned, base comprising a flat-folding tripod base with socket to accept plano-concave mirror gimbal peg, centre of foot supports square section brass pillar, engraved with objective focusing levels, triform stage mounted on square collar with screw clamp and fine focus screw to rear, top of square column terminates in winged screw to support brass compound tube, body tube incorporating a Martin lens above objective, twin drawer tube, eyepiece with sliding dust cover, in fine sharkskin case lined with red silk velvet with brass escutcheon and handle, containing six numbered objectives, live box, Bonnani stage, silver Leiberkuhn and case, magnifier, fish plate, wet cell, stage forceps, talc box and glass tube set of sliders, case 27cm wide Footnote: For an identical instrument unsigned but with original bill of sale from Benjamin Martin see Joseph Priestley's microscope at the Science Museum: https://blog.sciencemuseum.org.uk/joseph-priestleys-microscope-lens/