This petrological microscope is signed on the tube: Bausch & Lomb Optical Co., Rochester, NY, U.S.A. with serial number BK5907; this indicates 1945 as the date of manufacture. The instrument appears identical to the LC model shown in the illustration below taken from the cover of a 1945 issue of Science with the exception of the addition of the mechanical stage. It is constructed of brass, steel, and cast iron with a black enamel surface finish and chrome trim. Coarse focusing is by rack and pinion and fine focusing is by side-mounted calibrated knobs. The revolving stage is calibrated in degrees with a vernier reading to 3 arcminutes and is capable of a full 360 degree rotation. All movements of the mechanical stage are calibrated; the horizontal and vertical movements are read using a vernier.

The rack focusing substage has a double mirror on a swinging arm and polarizing condenser holding a Glan-Thompson prism in a rotating calibrated mount and with an iris diaphragm below. There is a knob that allows the top element of the condenser to be moved aside for low power work. A lever operates an additional iris diaphragm located between the upper and lower elements of the condenser. Finally, there is an additional lever that can block all the light coming through the condenser. The analyzer is a Ahrens prism set into a sliding holder and it is calibrated for rotation up to 60 degrees. The body tube contains a focusing Bertrand lens, mounted on a sliding holder, with its own iris diaphragm.

The original accessories, which are stored in a slide-in wood box and rack, consist of four objectives (4, 16, 32, and 40 mm labeled "strain free"), each with its own centering mount, three petrological eyepieces (5, 7.5, and 10x), a pin-hole eyepiece, an eyepiece adapter that allows the use of standard diameter eyepieces (two included, one for use with a micrometer insert), another adapter, chrome plated, of unknown function, two compensator plates, quartz wedge, and two nosepiece centering tools. The microscope, eyepiece rack, and accessory case are stored in the original wood case with handle and lock, but no key. The booklet, "Use and Care of the Microscope", is included.

The microscope is in very fine condition. All mechanical movements work well. The surface finishes are original and in very good condition showing hardly any blemishes. Both prisms appear clear and functional. The wood case is in fair condition, showing some wear and having a crack on the door due to wood shrinkage. An internal wood fitting on the door is broken. This is a fully functional and attractive instrument. It is a research quality instrument of its day.

Price: Sold

This item is large and heavy; please include $65.00 for shipping and insurance within the continental US. Shipping will be at cost if sent elsewhere.