UNUSUAL CALIPERS / FOLDING RULE, French, 19th century, 7″ (18 cm) overall (closed), of brass with iron fittings and end stops. The folding rule is divided from 0 to 12 French inches, by twelfths, and from 0 to 10 centimeters, by millimeters. The hinge center has a charming pierced iron six-pointed star, and the rule closes on shaped stellate designs. A sliding clampable cursor fits over the rule, forming outside calipers with readout in old and new (i.e., metric) measures. The cursor is pierced with a six-pointed star on one side, and with a “G” (for the maker), on the other. Condition is good noting some corrosion to the iron. We have seen only one other example of this folding combination, that clearly by the same maker, and in fact signed “Gillot.”
Ask the Dealer
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 firstname.lastname@example.org.