Pocket Case of Drawing Instruments Signed Martel

This miniature sharkskin pocket case is lined with green cardboard. An emblem of cherries is imprinted on the top and bottom of the case. The case holds 3-1/4" silver and steel fixed-point dividers; a hollow silver scribe with a pen point that inserts into the tube and a pencil lead inside the tube; and a 3-5/8" silver French-style sector. (See http://americanhistory.si.edu/collections/object-groups/sectors.)

One side of the sector has double scales of chords, running from 10 to 90, and for inscribed regular polygons, from 12 sides to 3 sides. A scale for diameters of bullets, running from 1/4 to 30, is along the outer edge of both legs. This side is marked: MARTEL (/) A GENEVE.

The other side has double scales of equal parts, running from 10 to 100, and for the specific weights of six metals. The outer edge of both legs has a scale for the caliber of shot, running from 1/4 to 27. A scalloped piece fits between the arms of the sector and may be used to lock the instrument into position. A square piece inside the hinge has a pinhole for a plumb line, although no plumb line is present.

Pierre Martel (1706–1767) was a Swiss engineer, mathematics teacher, maker of mathematical instruments, and geographer who used his own instruments to observe and explore glaciers in the Alps in 1742. He worked in Geneva from 1723 to 1743, in London from 1743 to 1746, and in Jamaica from 1746 to 1761.

References: Peter H. Hansen, The Summits of Modern Man: Mountineering After the Enlightenment (Cambridge: Harvard University Press, 2013), 32–33; Adler Planetarium, Webster Signature Database, http://historydb.adlerplanetarium.org/signatures/.

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