Ross - Wenham binocular microscope – circa 1857
One of the most important and impressive microscopes ever designed was the large bar limb model by Andrew Ross in the middle of the 19th century. This large and impressive stand by Andrew Ross of London, it is signed on the base: "A. Ross, London, 586." The original objectives are engraved with a date of 1857. The microscope is threaded for RMS standard lenses, which makes this a very early example of that standard. The microscope measures 20" high in closed position. It features a full mechanical stage with X/Y positioning and a rotating slide platform for full positioning of the slide. The sub-stage condenser assembly has two X/Y centering screws and a knob to rotate the condenser. A separate mechanical control adjusts the condenser height. The coarse focus is rack and pinion, and fine focus is with a knob behind the optical tube. All rack work is in fine operating condition. The plano-concave mirror is 3" diameter. The microscope disassembles for storage in its own case mahogany case with brass carry handle, two doors, locks and key. There is a separate optical tube used to convert the microscope to monocular work. The binocular tube is engraved, "WENHAM BINOCULAR, by Ross, London". This would be one of the earliest examples of a Wenham binocular microscope. The instrument is finished in lacquered brass with most of the lacquer present, but showing slight wear marks overall. Accessories include four original, signed objectives with their own brass canisters. One is a 1/2", another 1/4" (dated 1857), the third is a 1", and the fourth a 2". All canisters are signed, "A, Ross, London", indicating they are original to the system. The two binocular eyepiece sets are marked as "A", and "B". There are two monocular eyepieces. One is marked as "C" and "Kellner's Orthoscopic, Ross, London". A separate nicol prism eyepiece accessory also fits over this. There is a large substage condenser with four optical inserts. One is a standard optical unit; a second is a dark field optical unit; a third is a narrow optical magnifier; and the fourth is a nicol prism polarizer with accompanying analyzer. A wheel of stops controls the light. A standing bullseye condenser, live box, stage forceps, lieberkühn, and side reflector completes the accessory list. The microscopes impressive scale, full functionality, and fine mechanical condition make it a highly prized, classic collectible of one Englands most influential 19th century innovators.