Colomhia hehceen the Years 1820 and 1830. 5 



contiguous elevations which impede the circnlation of air, and 

 produce reflected heat. The various combinations of these cir- 

 cumstances may be considered as affording a rule of the increase 

 or diminution of temperature. Thus, La Guayra, situated on a 

 sandy beach backed by a perpendicular wall of rocks, has no 

 counterpoise to the excess of heat but the sea breeze, and the re- 

 mote influence of the ridge of the Silla, which no where reaches 

 the limit of perpetual snow. Humboldt considers it in conse- 

 quence as the hottest place on the shores of the New World, 

 (Personal Narrative, vol. iii, p. 386,) the mean annual tempera- 

 ture being 820-6; yet the observations I made during some 

 months' residence in Maracaybo give an annual mean of 84Q-63. 

 Nor is this surprising, when we consider the localities of both 

 places. In Maracaybo the sun's rays are reflected hom a barren 

 sandy soil, scantily sprinkled with Mimosas and prickly plants. 

 The mountain chains are too remote to have any influence on the 

 atmosphere, so that several years frequently pass without any 

 regular fall of rain. The vicinity of the lake, no doubt, acts 

 slightly as a refrigerant; but the city is built on the border of 

 its outlet to the sea, where it is both narrowest and shallowest, 

 and is consequently heated nearly to the temperature of the in- 

 cumbent atmosphere. Add to this, the small sandy elevations to 

 the north, which intercept the partial eff"ect of the sea-breezes, so 

 that they are scarcely felt, except in the months of December and 

 January, when the thermometer sometimes sinks to 73° ; yet the 



um even of these two months is not less than 81°; while 

 that of La Guayra from November to December at noon, is, ac- 

 cording to Humboldt, 75°-8, and at night 70°-9. (Personal Nar- 

 rative, vol. iii, p. 387.) Rio Hacha is situated on a sandy beach ; 

 the sea-breeze blows with such violence that boats can scarcely 

 land between ten in the morning and four in the afternoon. 

 These winds, however, sweeping over the hot plains of Core and 

 Maracaybo, have but a partial effect in lowering the temperature, 

 the annual mean of which is l°-98 less than that of Maracaybo. 

 I never saw the thermometer lower than 75°, nor above 89°. 

 In Santa Marta the average of the coolest months is 82° -25. The 

 thermometer, however, never rose during my residence there 

 above 87°. The soil is sandy, and the city is surrounded by 

 bare rocky heights to the north and south, which counterpoise 

 the cooling influence of the Sierra nevada, (snowy mountains.) 



med 



