CRAIG-FORM HIGH POWER MICROSCOPE, American, c. 1870. This 4-1/2″ (11 cm) tall white metal microscope is a vertical drum form with articulated plane mirror. But unlike the typical compound drum form, here a special high power lens is mounted at the top, and the specimen slide is mounted immediately below. Condition is fine.
In 1862 Craig received patent #34,409 for his simple microscope comprising a high power lens mounted just above the specimen slide slot, atop a vertical cylinder housing an adjustable mirror. A key feature of his patent was the lens, made with a globule of flint glass fused to a plate of crown glass. The focal point was at the bottom of the crown plate itself, which would be in direct contact with the specimen on slider, or fluid droplet specimen. No focus adjustment was necessary! Craig’s invention has been described by Bell (Rittenhouse 8, 73-77), who writes: “The first inexpensive American microscope was that patented in 1862 by Henry Craig of Cleveland, Ohio, one of the many self-taught inventors who flourished in 19th-century America. In 1861-62 Craig was working as a janitor in the Western Homeopathic College and living at the school. In 1863-64 he was ‘Manufacturer of the Craig microscope.'” It was produced in various forms in various materials, but all are rare. Although unsigned, the present example is unmistakably Henry Craig’s design.
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David and Yola Coffeen both have enjoyed academic careers, as planetary astronomer and as linguist/educator. But since 1982 (yes, 1982!) they have been full-time dealers in early scientific and medical instruments, under the name Tesseract. Selling primarily by catalogue (over 100 issued so far) they also have a web presence at www.etesseract.com, and can be contacted at [email protected]