made in Colombia between the years, 1820 and 1830. 153 



annual mean is 82°*20 ; that of Cumana is, according to 

 Humboldt, 81°-0. The breezes which sweep from the gulf of 

 Paria over the wooded Birgantine chain probably contribute 

 to lower the temperature. 



We have thus, on a calculation of six points on the Atlantic 

 coast of Colombia, a mean annual temperature of 82°'56*. 

 The shores of the Pacific, as far as the latitude of Payta, are 

 subjected to other influences, being almost entirely covered 

 by damp luxuriant forests; while the ocean itself is cooled, as 

 Humboldt observes, by the winds which blow constantly from 

 the south. This, however, is more perceptibly the case from 

 latitude 8° to 13°, where the air is cooled to an average of 

 71°-8. Betwixt 9° north latitude and 3° south latitude, if we 

 may trust to observations made at the five points of Panama, 

 Esmeraldas, el Morro, the island of Puna and Guayaquil, the 

 annual mean is 80°* 11, being 2°-45 less than the mean of the 

 Atlantic coast. A notable difference also arises from the su- 

 perior elevation of the Pacific chain of the Andes, and its more 

 immediate vicinity to the coast ; while the Venezuelan branch, 

 with the exception of the Santa Marta ridge, is both lower 

 and more inland. 



2. On penetrating into the interior of the country and ex- 

 amining the temperature of small elevations, we may take as 

 forming an aggregate specimen of the whole country, 1st, 

 the damp wooded valleys of the Orinoco and Magdalena; 

 2nd, the forests which border on the Pacific; and, 3rd, the 

 immense plains of Venezuela, alternately flooded and parched 

 with excessive heat. Humboldt assigns to the valley of the 

 Orinoco a mean temperature of 78°*2 The small number 

 of observations I have made on that of the Magdalena, would 

 give a mean of nearly 83°, which I should scarcely think too 

 high, considering the localities of the river, which flowing 

 from south to north, affords no channel to the sea breezes. 

 Its mass of water is also much less considerable than that of 

 the Orinoco, while its numerous sinuosities, and the low ridges 

 which border it in the upper part of its course, contribute to 

 render the air stagnant and suffocating. The temperature of 

 Honda, at 1200 feet of elevation, is as high as that of any 

 part of the coast, except Maracaybo. The unbroken forests 

 which extend from the roots of the Quitenian Andes to the 

 shores of the Pacific have a much lower temperature, caused 

 by the proximity of the snow-capped Cordillera, and the hu- 

 midity which prevails throughout the year. Accurate observa- 



* I have not included Cartagena, because the number of observations 

 is, perhaps, too limited to draw a conclusion as to the yearly temperature. 

 If we take them into the calculation the annual mean would be 82°-86, 

 which is probably too high. 



