First edition of one of the earliest scientific expeditions to California, sent out by the French government much to the consternation and suspicion of the Spanish, spurring the dispatch of Gaspar de Portolá in 1769 and hastening settlement of Upper California. Streeter describes the work as “A thrilling account of a race against time to reach Lower California before the transit of Venus occurred. After nerve-racking delays, which began in Spain, and narrow escapes from disaster, the goal was reached late in May. Two days after the transit was observed a malignant fever spread through the little group and Chappe d’Auteroche [1728-1769], who nursed the sick and dying, took it himself and died on the first of August. Mr. Cowan is quite incorrect in his note on this book, saying ‘this celestial phenomenon was visible only upon the coast of California.’ It was in fact visible throughout the western hemisphere and expeditions to observe it were sent to numerous stations. Also Spain not only knew of the expedition, but in the end co-operated in every way to make it a success.” According to most sources, the engraved map of Mexico City probably was based on one by José Antonio Alzate y Ramírez. Howes C299; Streeter Sale 2443 (for 1st edition). Bookplate of James Douglas on front pastedown, that of Jose Ramon de Velasco on verso of front free endpaper. Old ink signature of B. Dalton to top of title-page.