660 COSMOS. 



in the atmosphere, aiad of the quantity of rain owing to 

 the destruction of forests ;* 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 perpetual 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 nevadas 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 Anghiera, an account of the expedition of Colme- 

 nares, that the tropical snow region visible on the mountainous 

 shore of the Caribbean Sea, acquired a great and, we might 

 say, a cosmical importance. A connexion was now established 

 between the lower limit of perpetual snow and the general re- 

 lations 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 

 (opp dydwKpa}, 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 re- 

 garded by physicists, is contained in the celebrated inscrip- 

 tion of Adulis, which is considered by Niebuhr to be later than 

 Juba and Augustus. The knowledge of the dependence of the 

 lower limit of snow on the latitude of the place,f the first in- 

 sight into the law of the vertical decrease of temperature and 



* The Admiral, says Fernando Colon (Vida del Aim. cap. 58), as- 

 scribed 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 

 whilst 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 become much 

 more rare." This warning has remained almost unheeded for three cen- 

 turies and a half. 



t See vol i. p. 386, Examen crit., t. iv. p. 294; Asie 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 traveller 

 sinks up to the knees," 



