^82 COSMOS. 



Bacon ;* to the decrease of humidity in the atmosphere, and 

 of the quantity of rain owing to the destruction of forests ;f 

 to the decrease of heat with the increase of elevation above 

 the level of the sea ; and to the lower limit of the line of per- 

 petual snow. The fact of this limit being a function of 

 geographical latitude was first recognized by Peter Martyr 

 Anghiera in 1510. Alonso de Hojeda and Amerigo Vespucci 

 had seen the snowy mountains of Santa Marta ( Tierras 

 "levadas de Citarma) as early as the year 1500 ; Rodrigo 

 Bastidas and Juan de la Cosa examined them more closely in 

 1501 : but it was not until the pilot Juan Vespucci, nephew 

 of Amerigo, had communicated to his friend and patron An 

 ghiera an account of the expedition of Colmenares, that the 

 trojjical snow regioji visible on the mountainous shore of the 

 Caribbean Sea acquired a great, and, we might say, a cosmical 

 importance. A connection was now established between the 

 lower limit of perpetual snow and the general relations of the 

 decrease of heat and the differences of climate. Herodotus 

 (ii., 22), in his investigations on the rising of the Nile, wholly 

 denied the existence of snowy mountains south of the tropic 

 of Cancer. Alexander's campaigns indeed led the Greeks to 

 the Nevados of the Hindoo-Coosh range {ppr] dydvvKpa), but 

 this is situated between 34° and 36° north latitude. The 

 only notice of snow in the equatorial region with which I am 

 acquainted, before the discovery of America, and prior to the 

 year 1500, and which has been but little regarded by physi- 

 cists, is contained in the celebrated inscription of Adulis, which 

 is considered by Niebuhr to be later than Juba and Augustus. 

 The knov/ledge of the dependence of the low'er limit of snow 

 on the latitude of the place, $ the first insight into the law of 

 the vertical decrease of temperature, and the sinking of an 



* An observation of Columbus. (Vida del Almirante, cap. 55 ; Ex- 

 amen Crit., t. iv., p. 253 ; and see, also, vol. i., p. 316.) 



t The admiral, says Fernando Colon (^Vida del Abn., cap. 58), ascrib- 

 ed the extent and denseness of the forests which clothed the ridges of 

 the mountains to the many refreshing falls of rain, which cooled the air 

 while he continued to sail along the coast of Jamaica. He remarks in 

 his ship's journal on this occasion, that " formerly the quantity of rain 

 was equally great in Madeira, the Canaries, and the Azores; but since 

 the trees which shaded the ground have been cut down, rain has be- 

 come much more rare." This warning has remained almost unheeded 

 for three centuries and a half. 



t See vol. i., p. 329 ; E.xamen Crit., t. iv., p. 294 ; Aste Centrale, t 

 iii.. p. 235. The inscription of Adulis, which is almost fifteen hundred 

 years older than Anghiera, speaks of " Abyssinian snow, in which the 

 traveler sinks up to the knees." 



