Note 60 — THE PLATEAU OF CAXAMARCA, THE ANCIENT CAPITAL OF THE INCA ATAHUALLPA: AND THE FIRST VIEW OF THE PACIFIC OCEAN, FROM THE CREST OF THE ANDES.

p. 302.—“Of importance for the exact determination of the longitude of Lima.”

At the period of my Expedition, the Longitude of Lima was given in the maps published in the Deposito hidrografico de Madrid, from the observations of Malaspina, which made it 5h. 16m. 53s. from Paris. The transit of Mercury over the Sun’s disk on the 9th of November, 1802, which I observed at Callao, the Port of Lima, (in the northern Torreon del Fuerte de San Felipe) gave for Callao by the mean of the contact of both limbs 5h. 18m. 16s. 5, and by the exterior contact only 5h. 18m. 18s. (79° 34´ 30´´). This result (obtained from the Transit of Mercury) is confirmed by those of Lartigue, Duperrey, and Captain FitzRoy in the Expedition of the Adventure and Beagle. Lartigue found Callao 5h. 17m. 58s., Duperrey 5h. 18m. 16s., and FitzRoy 5h. 18m. 15s. (all West of Paris). As I determined the difference of longitude between Callao and the Convent de San Juan de Dios at Lima by carrying chronometers between them four times, the observation of the transit of Mercury gives the longitude of Lima 5h. 17m. 51s. (79° 27´ 45´´ W. from Paris, or 77° 06´ 03´´ W. from Greenwich). Compare my Recueil d’observations astron. Vol. ii. p. 397, 419 and 428, with my Relat. hist. T. iii. p. 592.