Selection of Books & Manuscripts
COURTANVAUX, Francois Cesar le Tellier, marquis de (1718-1781); [LE ROY, Pierre] Journal du voyage de M. le marquis de Courtanvaux, sur la fregate l'Aurore, pour essayer par ordre de l'Academie, plusieurs instrumens relatifs a la longitude. Mis en ordre par M. Pingre, nomme par l'Academie pour cooperer a la veerification desdits instrumens, de concert avec M. Messier.
A Paris: A Paris : De l'Imprimerie royale., MDCCLXVIII  FIRST EDITION. Quarto. Recent full calf binding, central lozenge design, spine in blind tooled panels with gilt lines and contrasting morocco title label, some very light browning and occasional light spotting. Pagination pp. , viii, 316, , collated and complete with 5 engraved plates (4 folded) and the folded engraved map. [National Maritime Museum Catalogue v.I. 1149a; Norman 1335].
Courtanvaux had been destined for a military career until ill-health forced him to resign in 1745. He subsequently took up the the study of the natural sciences, and was elected to the Academie des Sciences in 1764. The present work is his report of a voyage in the frigate l'Aurore - a vessel that Courtanvaux fitted out at his own expense to allow for the accurate assessment under everyday conditions of the various competitors for the prize offered by the Academie (for the first successful method of accurately measuring longitude). The main contender assessed was the Horloger du roi from 1754, Pierre Le Roy (1717–1785). He had invented a completely original marine chronometer in the 1750s, which he perfected over the next decade and presented to Louis XV in 1766. In 1767 Le Roy entered his machine, which "embodied all the principles upon which later marine chronometers were constructed" (Norman), in the competition. The present voyage between Le Havre and Amsterdam was the first practical trial to which it was subjected. Le Roy was awarded a double prize in 1768, for his chronometer and for his memoir describing it. The first four chapters give a detailed account of the different methods employed from the 15th to 18th centuries to determine longitude. The rest of the work, written by Courtanvaux, Pingre and Messier, describes the voyages and the experiments carried out. The final chapter is devoted to a recapitulation of Le Roy's marine clocks.