WOODEN SURVEYING SQUARE, French, c. second quarter 19th century, signed “Castex Aine a Toulouse.” The turned walnut(?) instrument measures 4-3/4″ (12 cm) tall, with integral staff fitting and orthogonally cut sighting slits to lay out right angles for fields, buildings, etc. It is an unusual all-wood instrument, in very fine condition. This “Castex the elder” maker is probably connected with the balance maker listed by Marcelin, working in Toulouse in 1852.
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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]