A MIDDAY-LINE RECKONER, Austrian, c.1900, signed “Neuhöfer & Sohn in Wien.” Made of heavy brass, finely machined and standing 4-1/4″ (11 cm) high, this unusual form of noon mark has a pinhole on top and a vertical scribe line passing through it and down to the base. In use one can plot, on a leveled plane table, the meridian sun’s projection through the pinhole, giving the direction to geographic North. Placing a trough compass along this line immediately gives the magnetic declination, i.e., the local deviation between magnetic North and geographic North. An unusual device, reminiscent of the monumental noon mark projections in cathedrals, in very fine condition complete with instructions and card box.
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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@example.com.