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Swift "Challenge" binocular brass microscope - c.1878

A fine Swift "Challenge" binocular brass microscope with extensive optical system. It measures 15 " tall in closed position, is signed, "James Swift, 43 University St., London W.C." on the base, and dates to circa 1878. The "Challenge" model was first introduced in 1877. In 1878 Swift began using the spiral rack and pinion focus along with rack and pinion eyepiece separation control. Both designs are present on this microscope. Fine focus is with a nosepiece micrometer knob. The rotating mechanical stage has full lateral movement. All rack work is in excellent operating condition. The sophisticated substage condenser is a Webster type with a removable optical unit. This optical unit has a lever with a swing-in darkfield stop. The condenser rotates through three positions. One position contains a polarizer along with a wheel of filters. A second has a wheel of seven varying stops. The third is a larger opening with a slip in ring intended to hold filters in place. An analyser is built into the nosepiece on a sliding tray. The analyser is in need of a polishing to remove surface scratches that blur the image. The plano-concave mirror is excellent on the concave side, and has age spotting and edge wear on the plane side, but is usable as is. Five original Swift lenses and matching signed brass canisters comprise the optical system along with two sets of binocular eyepieces. Lenses include a 4", 2", 1", ",and 1/8". As with all Wenham style binoculars, only short focal length lenses produce a binocular image. The prism slides out of the light path thereby coverting the microscope to monocular viewing, which is necessary only with the 1/8" lens. One of the eyepieces is equipped with a removable internal micrometer ruling. The optical system is in overall excellent condition, noting the analyser already mentioned. The microscope is finished in lacquered brass with a japanned brass base. The coverage is complete with age spotting and some surface scratches overall. Accessories include a live box, fishplate, and a rare parabolic reflector that comes in its own lined leather case. The microscope and accessories fit into a hand dove-tailed mahogany case with brass carry handle, lock and key. The case is in very fine usable condition. The Swift "Challenge" model has always been a dependable model that went through numerous variations. This early one, outfitted with petrological attachments, is a fine example of the innovative thinking that went into these Swift instruments.

Item 1278

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