in Colombia between the Years 1820 and 18S0. 13 



on the table lands of the equator and the coast of the Pacific, 

 we find it to vary from 0° in the damp forests of Esmeraldas 

 to 97°' 1 on the elevated plain of Cayambe; the experiments 

 in both places being made during June and July, the summer 

 months both of the coast and mountains. The average me- 

 dium for the low lands is 23°-85 ; for the Cordillera 44°-36 of 

 the hygrometer constructed upon Leslie's principle ; but we 

 are in want of sufficient data for those elevations which ap- 

 proach to the limit of perpetual snow. To judge, however, 

 from a small number of observations made on the mountain 

 of Cayambe at 12,705 and 14,217 feet of elevation, and at 

 the hut of Antisana at 14,520 feet, where the hygrometer 

 was found to give 16°'5, 13°'9, and 30°*3, it would not seem 

 that the dryness of the atmosphere increases in ratio of the 

 elevation; at least in the neighbourhood of snowy mountains, 

 where a continual moisture is exhaled, and heavy mists sweep 

 over the soil towards evenings even of the fairest days. 



To estimate the general distribution of temperatures through 

 the vast territory of Colombia, we may conveniently consider 

 it as divided into five zones. 1st, That of the level, or nearly 

 so, of the ocean. 2nd, That of the small elevations, from 500 

 to 1500 feet. 3rd, That of the slopes of the Cordillera, from 

 2000 to 7000 feet. 4th, That of the elevated plains, or table 

 lands, from 8000 to 10.000 feet; and 5th, That of the jmra- 

 mos, from 11,000 feet to the limit of perpetual snow. 



1. The degree of heat at or near the level of the ocean is 

 modified by a variety of local circumstances, which may be 

 ranged under the following heads : proximity of the sea ; of 

 great rivers or lakes; of lofty ridges of mountains; of exten- 

 sive forests; of contiguous elevations which impede the circu- 

 lation of air, and produce reflected heat. The various com- 

 binations of these circumstances may be considered as afford- 

 ing a rule of the increase or diminution of temperature. Thus, 

 La Guayra, situated on a sandy beach backed by a perpen- 

 (Ucular wall of rocks, has no counterpoise to the excess of 

 heat but the sea breeze, and the remote influence of the ridge 

 of the Silla, which nowhere reaches the limit of perpetual 

 snow. Humboldt considers it in consequence as the hottest 

 place on the shores of the New World (Personal Narrative, 

 vol. iii. p. 386.), the mean aimual temperature being 82°*6; 

 yet the observations I made during some months' residence 

 in Ma'racaybo give an annual mean of 84°*63. Nor is this 

 surprising, when we consider the localities of both places. In 

 Maracaybo the sun's rays are reflected from a barren sandy 

 soil, scantily sprinkled with Miinosas and prickly plants. The 

 mountain chains are too remote to have any iiiHuenceon the 



