Voyage fait par ordre du Roi en 1768 et 1769, à différentes parties du monde, pour éprouver en mer les horloges marines inventées par M. Ferdinand Berthoud. Première[-seconde] partie, ... Paris, Imprimerie Royale, 1773. 2 volumes. Large 4to (27 x 20.5 cm). With 5 numbered folding engraved plates in volume 1 (4 maps of the Atlantic Ocean, the Canaries, the Azores, etc., and 1 plate with topographic diagrams), 1 folding engraved plate with geometrical figures illustrating the determination of latitude[!], and 5 folding letterpress tables in volume 2. Contemporary gold-tooled mottled calf.

[2], LXXIX, [1 blank], 803, [1 blank]; [2], 622, XL, [2 blank] pp.First edition of an account by Charles Pierre Claret, Count Fleurieu (1738-1810), of the first voyage made to test the chronometers invented by his mentor, Ferdinand Berthoud (1727-1807). They were developed to keep accurate time at sea in order to solve the problem of the determination of longitude, to make it possible for ships to easily determine their position. Berthoud closely followed the work of Harrison in England, who had already proven the efficacy of his chronometer no. 4 in 1761, but refused to allow Berthoud and others to examine it. During the voyages described in the present work, Fleurieu tested Berthoud's chronometers as well as his own instruments on board the ship Isis, travelling to Cadiz, the Canaries, the Antilles, Santo Domingo, the Atlantic Ocean, Madera, and several other places. The results showed their success even beyond his own expectations. The present work is complete with the appendix.With an owner's inscription on both title-pages. With only some minor, mostly marginal water stains at the beginning of volume 2. Folios e2 and e3 misbound at the end between 4I1 and 4I2. In very good condition.l Bibl. horlogère de Monsieur R.P. 196; Chadenat 2617; Gould, p. 96 note; Tardy, p. 99.