LORD’S CALCULATOR, English, c. 1900, signed “R. Waddington, Coventry.” The 2-3/4″ (7 cm) plated brass watch case is glazed in front, and fitted with two winding knobs and side mounting block. The calculator has four concentric circular scales (labeled A, B, C, and D), divided on silvered brass, the numerals colored in red and black. Two of these scales are independently rotatable by the knobs; no cursor is used. Condition is very fine and functional, noting a little wear to the finish. Lord’s sturdy pocket calculator is quite rare — even Hopp records only its existence, without details.
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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].