Gnomonique Elementaire

A. Lille et A. Paris: Chez Vanackere et Chez Courcier, 1806. First Edition. Wraps. Very Good. First Edition. [6], 26 pages plus 10 figures on four folding plates. Plates marked "Durig, a Lille" 8vo. Original pink wrappers. Marginal worming not affecting text or images. Spine paper cracked, cords holding. Rare in the original wrappers. Wraps. Gnomonics (The art or science of dialing, or of constructing dials to show the hour of the day by the shadow of a gnomon.) was of great interest in France during this period. After the theory of dialing was published in the Royal Academy of Sciences in 1707, many treatises on the subject appeared in the 18th century. (see Recreations in Mathematics and Natural Philosophy ... by Ozanam for a useful discussion).

A pencilled note "par Delezenne", suggests a likely attribution to Charles Delezenne (1776-1866) of Lille, a scientist and mathematician who wrote various scientific treatises later in his life. Delezenne returned to Lille in 1805, replacing Testelin as the Chair of Mathematics. Houzeau & Lancaster 11704 corraborates this attribution. While rare (only few copies listed in OCLC/Worldcat and one for sale as of this writing), this treatise is fairly late for a work on the mathematics of the subject.