452 PLATEAU OF CAXAMARCA. 



alone decide the much discussed problem either affirmatively or 

 negatively. That will be done at last which should, and, had my 

 advice been taken, would have been done in the first instance. 



( 19 ) p. 436. a That which is awakened in us l>y childish impressions 



or ty tlie circumstances of life." 



On the incitements to the study of nature, compare Cosmos, bd. 

 ii. s. 5 (English edit. vol. ii. p. 5). 



( 20 ) p. 437. " Of importance for the exact determination of tlie 



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 Fitz Roy in the Expedi- 

 tion of the Adventure and Beagle, Lartigue found Callao 5h. 

 17m. 58s., Duperrey 5h. 18m. 16s., and Fitz Roy 5h. 18m. 15s. (all 

 west of Paris). As I determined the difference of longitude be- 

 tween Callao and the Cpnvent 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 6' 3" W. from Greenwich). 

 Compare my Recueil d' observations astron. vol. ii. pp. 397, 419 and 

 428, with my Relat. hist. t. iii. p. 592. 



POTSDAM, June, 1849. 



