394 AMAZONIA AND LA PLATA. 



always prevail in Patagonia, where norf.li-west winds set regularly for a part of 

 the spring and throughout the whole of the summer season. They blow at times 

 with such fury that riders are unable to keep the saddle, and have to dismount 

 and seek shelter in some cleft of the rocks. In these caùadones an arborescent 

 vegetation is able to maintain itself ; but on the arid storm-swept plains nothing 

 can thrive except low growths, bush, and herbage. The gales usually rise with 

 the sun, and continue to increase in violence till the afternoon, when they subside, 

 a dead calm often prevailing at night. 



In the extreme south the aerial currents are far more capricious in the 

 labvrinth of fiords, inlets, sounds, and narrow channels of Tierra del Fuego than 

 on the open Patagonian steppe lands. As had already been observed by the 

 navigator Anson, in the seventeenth century, fine weather never lasts very long 

 in these high southern latitudes. The very clearness of the atmosphere is an 

 indication to the weather-wise of j^ending storms. 



As a rule, the rainfall decreases gradually in the direction of the south. On 

 the Tucuman plains it is heavier than in the Argentine Mesopotamia, more copious 

 in this region than in Bue.nos Ay res, in Buenos A y res than in Patagonia. There 

 is also a falling oiï in the direction from east to west, aridity increasing with the 

 distance from the seaboard. Here dews are copious, and fine drizzly rains occur, 

 like the "Scotch Mists " of EurojDC. But farther inland, and notably in the San 

 Juan district, such plienomena are almost unknown, and are replaced by tre- 

 mendous downpours, at times accompanied by thunder and hail-storms. Such ■ 

 heavy showers appear to be an abnormal phenomenon, which is attributed to the 

 conflict of opposing aerial currents. At Buenos Aj'res, and on the surrounding 

 plains, snow is of extremely rare occurrence. Nevertheless, Hermann Burmeister 

 was able to record the fall of a few flakes, as an exceptional event, in the year 

 1871. 



Taken as a whole, Argentina, even on the seaboard, lacks sufiicient moisture for 

 agricultural pursuits. The people of Buenos Ayr es have not yet forgotttm the 

 gran seen, " great drought," which prevailed from 1827 to 1831, and during which 

 only a few passing showers fell on the plains. In the interior these droughts 

 last even longer ; but here the settlers depend not so much on the rainfall as on 

 the melting snows of the uplands, which feed the irrigation rills, and on the 

 artesian wells that have been sunk to a depth of 300 feet and upwards in many 

 districts. 



It would, however, almost seem as if the climate has everywhere become drier, 

 snow being apparently less abundant than within a recent epoch. To the lack of 

 moLsture, whether under the form of snow or rain, is due the exhaustion of so 

 many rivers on the northern plains and in Patagonia. In the " accursed lands " 

 traversed by the Bios Colorado and Negro, mere channels destitute of any aflluents, 

 showers are extremely rare, and at times not a drop falls for years together. The 

 stations on the railway lines in the solitudes south of Buenos Ayres receive their 

 water supply rcgularl}^ with each train. Elsewhere travellers have to put up with 

 the brackish fluid that oozes in many places from the ground. In these districts 



