Beck Small Best Wenham-type binocular compound microscope
Date: 1876
Inventory Number: 1122a
Classification: Microscope
Dimensions:microscope: 44 × 25 × 24 cm (17 5/16 × 9 13/16 × 9 7/16 in.)
case: 15.9 × 47 × 24.2 cm (6 1/4 × 18 1/2 × 9 1/2 in.)
Accessories: oculars (2) in microscope; Darker's selenite retarding filters (3); wheel diaphragm; mechanical rotary stage; stage slider. Other accessories are in the case (1122b), including monocular draw tube; oculars (3); objectives in cans (5); empty can; Lieberkühn; polarizing set; slides; camera lucidas (2); etc.; plus a Beck patent substage condenser (1122c); and apertometer (1122d).
Bibliography:A Treatise on the Construction, Proper Use, and Capabilities of Smith, Beck, and Beck's Achromatic Microscopes
DescriptionThis is a Beck "Small Best" Wenham-type binocular compound microscope, convertible to a monocular microscope, and with a full complement of accessories. Due to the complexity, the objects have been divided into the following:
1122a: Beck convertible binocular-monocular microscope
1122b: Beck case with objectives, oculars, and common accessories
1122c: Beck patent revolving substage condenser
1122d: Beck Cheshire's apertometer
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The Wenham-type binocular microscope has a three-legged folding base upon which rise a turned pillar. A curved arm is attached to the hinge joint and carries a binocular tube, which is adjustable up and down by means of rack and pinion. Two ocular tubes are connected by means of a long horizontal screw and a pair of racks, which raise them up and down together in order to alter the interocular distance. Each ocular tube carries an eyepiece. The base of the body tube has an objective, which is removed when the instrument is folded up for storage in its box. Coarse focus is by means of rack and pinion of the body tube. Fine focus is by means of a screw mounted on the lower front end of the tube. This screw acts on a lever connected to the objective. A removable prism box is inserted in the nosepiece above the objective in order to reflect half of the rays passing through the objective into the additional tube of the binocular microscope. The arm has a rectangular slot with a locking screw; this is for holding the bull's eye condenser when in use.
When the user wishes to employ the microscope as a monocular instrument, the racked ocular tube on the right side is removed, and a spare ocular draw tube (stored in the case) is substituted. The brass ocular tube is calibrated from 0-6 inches with divisions every tenth inch.
The microscope has a circular rotating stage with a divided limb marked 50°-0°-250° counterclockwise starting from the right rear by the arm. 90° is directly at the front. On top of this rotating platform is a mechanical stage movable in x-y direction. A dovetailed plain stage mounts on top of this and is adjustable by hand. It carries a pair of blackened slide ledges that are independently dovetailed to it. Each ledge has a pair of brass knobs, and one has a pair of steel springs.
Substage apparatus includes a bracket that descends from the lower end of the arm. The bracket has a pair of knobs that engage rack and pinion in order to move up and down a parallel brass bar to which is attached a centering ring. The ring carries a sleeve topped by a rotating wheel diaphragm. A condenser or polarizer can be inserted as desired. A slot in the sleeve holds three swing out mounts, each with a rotating polarizing selenite filter marked "P ↑ A" (for positive axis). The top filter is marked 1/4; the middle, 3/4; and the lower, 9/4. These are described by Beck as "Darker's three retarding-films of selenite." They retarded the wave of polarized light and so increased the brilliancy of colors under high powers.
The substage plano-concave mirror is fork-mounted to an swiveling arm attached to the lower end of the arm behind the bracket.
The compound microscope comes with a fitted mahogany case filled with accessories. These are catalogued separately as 1122b, 1122c, 1122d.
Signedon front foot: R & J. BECK 31. CORNHILL LONDON
Inscribedserial no. on front foot: 7673
Historical AttributesThis microscope was Alexander Agassiz's personal instrument. It was used at his Marine Biological Laboratory in Newport, Rhode Island, where Agassiz summered. The instrument appears with Agassiz in a portrait that shows him working in this lab. Corrosion on parts of the microscope are probably due to contact with marine creatures and sea water.
This microscope was given to the Ernst-Lewis Collection on May 18, 1936 by Dr. Thomas Barbour, Director of the Museum of Comparative Zoology.
According to the correspondence between Conrad Beck, managing director of R. & J. Beck, and Dr. Frederic T. Lewis in 1939, the microscope is the type called the "Small Best" and was made in 1876. With all the accessories, it would have cost between £60 and £80.
Primary SourcesRichard Beck, A Treatise on the Construction, Proper Use, and Capabilities of Smith, Beck, and Beck's Achromatic Microscopes, 3rd ed. (London: John van Voorst, 1865).
W. T. Suffolk, "On Microscopical Manipulation," The Chemical News, 6 no. 2, American reprint (February 1870): 53-60.
ProvenanceAlexander Agassiz, Marine Biological Laboratory, Newport, Rhode Island, c. 1876; Museum of Comparative Zoology, Harvard University, c. 1910; transfer by Thomas Barbour, MCZ Director to the Ernst-Lewis Collection of Microscopes (inv. no. 122), Harvard Medical School, May 18, 1936.