on the Climate of the Canary Islands. 97 



astonishment would they have seen mountains in motion, than 

 such matters brought to them through the air from the west. 

 But, by this striking occurrence, the returning current in the 

 upper regions was proved, and with it the theory of the trade- 

 winds, for which we are indebted to Hadly (Phil. Trans, vol. xvi. 

 p. 151.), was become something more than conjecture. With 

 not less certainty can this current be daily observed in the Ca- 

 nary Islands ; for the Peak of TenerifTe is high enough to reach 

 it even in the middle of summer. There is scarcely any account 

 of a journey to the top of the Peak, in which mention is not 

 made of the violent west-wind blowing there. Humboldt as- 

 cended it on the 21st of June ; and, when arrived at the brink 

 of the crater, the raging west- wind scarcely allowed him to stand 

 ^on his feet, (Relat. i. 132.) Had such a wind blown at this 

 season at Santa Cruz, or at Orotava, people would have been as 

 much alarmed by the circumstance as they were in Barbadoes 

 by the clouds of ashes. I found a similar, though somewhat 

 less powerful, west-wind at the summit of the Peak on the 19th 

 of May ; and George Glass, an attentive and accurate observer, 

 who, as a seaman, had for many years carefully explored the winds 

 of these islands, says in his work, which still contains much valu- 

 able information, that strong west-winds always blow upon the 

 heights of these islands, when those from the north-east prevail 

 below, '' which,'' he adds, "• takes place, as I believe, in allparts 

 of ike world in which there are trade-winds^ " I venture not,*" 

 he farther adds, " to explain this circumstance, but it certainly 

 is so on the Peak of Teneriffe, and on the heights of some others 

 of these islands,'' (History of the Canary Islands, p. 251.) 

 Glass knew the islands too well not to speak here from his own 

 experience. 



These winds descend gradually upon the mountains from 

 the high regions of the atmosphere, as is evidently seen from the 

 clouds, which, after October, cover the top of the Peak from the 

 south, and which appear always lower till they rest on the 

 range of mountains, more than 6000 feet high, between Oro- 

 tava and the southern coast, and there break out into dreadful 

 thunder-storms. After that, perhaps, a week may pass, or more, 

 before they are felt on the sea-coast. There they continue to 

 APRIL — JULY 1826. G 



