Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Microscope, Wide Field Binocular
This microscope is designed to provide low magnifications of objects in three dimensions. Widely used for dissections, small parts assembly and inspection, jewelry inspection and similar operations requiring an enlarged, stereoscopic view, these instruments consist of two independent microscopes. Each has an erecting prism system and is focused on the same object from a slightly different angle to give an exaggerated stereoscopic view. Because of the inclinations of the optical axis of the two microscopes from the vertical, only the center of the field is in focus for both, however the composite image appears sharp over the entire field due to the opposite nature of the focusing errors, the accommodation of the eye, and the great depth of view of the low power objectives. This type of low power, binocular microscope was first designed by Greenough in 1897, and was first manufactured by Zeiss using standard microscope optics.1 Leitz was the first manufacturer to significantly improve the design with the use of large diameter (1.25"), well corrected eyepieces giving a bright, flat, and large field of view.2
Greenough type "binocular" microscope; 10.5 x with two a15 oculars (1 1/4" diameter). The body consists of two binocular like leather covered tubes, 6" long, enclosing porro prism erecting optics, which may be rotated to accommodate inter ocular distance. The body is mounted through a brass dovetail to a focusing rack which is in turn mounted through a second dovetail to the arm (the rack may be removed). An 11" articulated black painted brass arm rotates 360° on a focusing sleeve which rides on a 14" pillar with rack and pinion movement. The pillar is attached to a heavy, solid, round cast iron base, 7" dia x 1 3/4" high at post. All exposed metal parts are nickel plated or black wrinkle enameled. There is a serial number? (6420) stamped on a plate on the top of the optical module focusing/mount mechanism.
Similar to Ernst Leitz Stand (dated 1925) as illustrated in The Billings Microscope Collection, 2nd ed, figure 275 (signed "E. Leitz, Wetzlar, Germany, 2624"). What appears to be an identical stand is illustrated in the 1927 Eimer & Amend BCM Catalog (Eimer & Amend, New York, 1927) as item 26334 on pg 495. The optical portion is of an earlier design, but the optical unit is also illustrated in the catalog on pg 498 on a standard stand as item 26370. This microscope was a gift from Dr. William Allen of HSU's Biology Department. He later stated that he believed it had originally been William Lanphere's.
1 Needham, George Herbert. The Practical Use of the Microscope. Charles C. Thomas Publisher. Springfield. (1958) p. 64.
2 Ibid p. 65.
© R. Paselk