422 Scientific Intelligence. — Meteorology. 



non produced in other places, and upon a very extensive scale ? 

 I say upon a great scale, because it appears to me beyond doubt 

 that the land breeze which is regularly perceived during the 

 night in certain seas, and the sea breeze which succeeds it in the 

 morning, are likew^ise winds of aspiration or of suction. 



Saussure, during his sojourn at the Col-du-Geant, was assail- 

 ed by the wind of an extremely violent tempest, which inter- 

 vals of the most perfect calm periodically interrupted. As the 

 stormy winds suddenly changed their direction to the extent of 

 30 or 40 degrees, the illustrious philosopher of Geneva explain- 

 ed the strange intervals of calm which he witnessed, by suppos- 

 ing that sometimes the wind blew according to the direction of 

 one or other of the Alpine ridges which protected his station at 

 the Col. 



This explanation of the intermission of the wind cannot be 

 general, for Captain Cook has observed the same phenomenon 

 in the open sea. Thus he writes in his second voyage. " When 

 the ship was in 45° S. lat., and 28° 30' E. long, from Paris, the 

 night proved exceedingly stormy. The wind blew from the 

 south-west in most violent squalls. In short intervals between 

 these, the wind almost completely died away, and then recom- 

 menced with such fury that neither our sails nor rigging could 

 stand it." 



Captain Duperre has stated that he has sometimes seen the 

 same thing : and this forms one curious subject of observation. 

 It is also desirable to attend to the winds upon land, which often 

 blow for whole days in the plains, if not with intervals of per- 

 fect calm, at least with changes in intensity, which Saussure 

 estimated at the half, or at least two- thirds, of the usual intensity. 



Meteorology and physiology have still much to gain from the 

 zeal of travellers on the subject of the hot winds of the desert, 

 known in Africa under the names of Seimoum, of Kamsin^ and of 

 Harmattan^ winds which, in attaining the several islands of the 

 Mediterranean, or the coasts of Italy, France, and Spain, become 

 the Sirocco. The description which certain travellers have given 

 of the effects of the seimoum are evidently exaggerated. It also 

 appears evident that these effects, whatever they are, depend in 

 a great degree upon their high temperature, and the extreme dry- 

 ness which the shifting sands communicate to the atmosphere ; 



