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Traitté du mouvement local et du ressort. Dans lequel, leur nature, & leurs causes, sont curieusement recherchées, & ou les loix qu’ils observent dans l’acceleration & les pendules, & encore dans la percussion & la reflexion des corps, sont solidement establies.

Lyon: chez Anisson, et Possuel, 1682.

Collation: 12mo: *⁶ A–T¹² V⁶ (V6 +1), 234 leaves, pp. [xii] 465 [5], errata on V5v and V6r, V6v blank, final inserted leaf ‘Extrait du privilège’, verso blank. Woodcut device on title, woodcut headpieces and initials, woodcut text diagrams.
Condition: 159 x 88mm. Paper a little discoloured as usual.
Binding: Contemporary sprinkled calf, gilt spine, lettered direct in second compartment, red and brown sprinkled edges. Head and tailcaps chipped, corners and joints rubbed.
Provenance: Earls of Macclesfield with South Library Bookplate and embossed crest on prelims (Sotheby’s 14 April 2005, lot 1383).
References: Baillie 111; Sommervogel II, 1044,7.
Price: £1,500

First and only edition. This copy has a Privilège leaf which is not normally present inserted in the final gathering.

¶ A detailed treatise on the physics of springs, pendulums and the percussion of bodies,  which seems to have been overlooked by historians. It was his last work, found among his papers after his death.

Hutton called the Jesuit Dechales ‘an excellent mathematician, mechanist, and astronomer... generally admired and beloved at Paris, where for four years together he read public mathematical lectures in the college of Clermont.’ He later moved to Marseilles and was afterwards professor of mathematics at Turin where he died in 1678. His Cursus mathematicus (3 vols folio, Lyons 1674) was a popular and widely used text-book, as was his edition of Euclid. The only recent study of Dechales is the article by Nardi cited below which deals with Dechales work on accelerated motion in the Cursus. Deschales supported Galileo’s time-squared law of uniformly accelerated motion, and anticipated Newton’s concept of gravity related to the free fall of bodies. Yet this later work on related topics is not discussed by Nardi, and is not noticed by William Schaaf in his article on Dechales in DSB.