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Large brass microscope by Ross– circa 1859

A large and impressive stand by Andrew Ross of London, it is signed on the base: "A. Ross, London, 490." The signature and serial number would date the instrument to the mid-1850’s. The microscope is threaded for RMS standard lenses, which argues for a date after 1858. To further complicate matters, a paper label inside the case bears the address of 112 New Bond Street, which is where Ross was located from 1880 to 1893. Perhaps the instrument was returned to Ross for refitting during this time frame. 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 an indicator knob behind the optical tube. All rack work is in fine operating condition. The 3" diameter plano-concave mirror is excellent on its plane side, and shows age clouding on the concave side. The microscope disassembles for storage in its own case mahogany case with brass carry handle. The instrument is finished in lacquered brass with most of the lacquer present, but showing age wear marks overall. Accessories include two objectives with their own brass canisters. One is an unmarked 1", and the other is a Henry Crouch 1/6". As mentioned, the microscope accepts standard RMS threaded objectives. The two eyepieces are marked as  "D", and  "A". There are four substage condensers. One is a standard optical unit; a second is a dark field optical unit; a third is a wheel of stops; and the fourth is a nicol prism polarizer with accompanying analyzer. A stage forceps completes the accessory list. The microscope’s impressive scale, full functionality, and fine mechanical condition make it a highly prized collectible of one England’s most influential 19th century innovators. 

Item 1183

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