Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

502 RAINS — COLNETT MOISTURE. Oct. as in most places near the equator. The time of the year for the rains is in November, December, and January : then there is oftentimes excessive dark tempestuous weather, mixed with much thunder and lightning. Sometimes before and after these months there are moderate refreshing showers ; but in May, June, July, and August, the weather is always very fair." ' I can add nothing to this excellent description, except that heavy rollers occasionally break upon the northern shores of the Galapagos during the rainy season above-mentioned though no wind of any consequence accompanies them. They are caused by the ' Northers,' or ' Papagayos,' which are so well known on the coast between Panama and Acapulco. Col- nett also gives a good description of these islands : — in his voy- age, p. 58, he says, " I consider it as one of the most delightful climates under heaven, although situated within a few miles of the equator." The buccaneers often resorted to them for re- freshments, and as a place where they might refit their vessels, share out plunder, or plan new schemes of rapine, without any risk of being molested. Striking instances of the manner in which high land deprives air of its moisture may be seen at the Galapagos. Situated in a wind nearly perennial, those sides only which are exposed to it (the southern) are covered with verdure, and have water : all else is dry and barren, excepting such high ground as the pass- ing clouds hang upon indolently as they move northward. In a similar manner may Ave not conclude that western Peru is deprived of rain— since the easterly trade wind which carries moisture, and consequent fertility, to eastern Peru, is drained, or dried, as it crosses the Andes ? And may we not extend this reasoning to other countries similarly situated, such as Patagonia, perhaps Arabia, and even Africa, upon whose arid deserts no moist wind blows.'' Currents of air, moving from ocean to land, convey vapour ; but as these currents pass over * During the rainy season, or from November to March (which is not, however, at all to be compared to a continental rainy season) there are calms, variable breezes, and sometimes westerly winds : though the latter are neither of long duration, nor frequent.