i 



ANNOTATIONS AND ADDITIONS. 125 



covered Andes, but rather to the fogs (garua) which veil 

 the solar disk, and to a cold sea current which, commenc- 

 ing in the antarctic regions and coming from the south-west, 

 strikes the coast of Chili near Valdivia and Conception, and 

 thence streams rapidly along the coast to the northward, as 

 far as Cape Parina. On the coast, near Lima, the tempera- 

 ture of the Pacific is 12.5 Keaumur (60.2 Fahr.), whilst 

 in the same latitude out of the current it is 21 E. (79.2 

 Fahr.) It is singular that so striking a fact should have 

 remained unnoticed until my visit to the shores of the 

 Pacific, in October 1802. 



The variations of temperature of different regions depend 

 in a great degree on the character of the bottom of the 

 "aerial ocean," or on the nature of the floor or base, 

 whether land or sea, continental or oceanic, on which the 

 atmosphere rests. Seas, often traversed by currents of 

 warmer or colder water, (oceanic rivers), have an effect very 

 different from that of continental masses, whether unbroken 

 or articulated, or of islands, which latter may be regarded 

 as shallows in the aerial ocean, and which, notwithstanding 

 their small dimensions, exert, often to a great distance, a 

 notable influence on the climate of the sea. In continental 

 masses we must distinguish between sandy deserts devoid of 

 vegetation, savannahs or grassy plains, and forest-covered 

 districts. In Upper Egypt and in South America, Nouet 

 in the former, and myself in the latter, found respectively 

 at noon the temperature of the ground composed of granitic 

 sand 54.2 and 48.4 Reaumur (154 and 1 41 Fahr.) Many 

 careful observations in Paris have given, according to Arago, 

 40 and 42 Reaumur, 122 and 120.5 Fahrenheit, (Asie 



