HAIL. 319 



by solar rays in its course, and also a slight mixture with less cool 

 strata of air. 



" This being granted, one easily understands that, as at the 

 extremity of South America, in latitudes where temperatures of 

 12, 15, or even of 20 below zero (centigrade) are occasionally 

 possible in winter on the surface of the ground and near the level 

 of the sea, a strong wind, that is to say, a great mass of air moving 

 W.S.W. to E.N.E., beat against the mass of the southern Andes, 

 where, by its acquired velocity, it ascended, still keeping its E.N.E. 

 direction. . . . Then, in the higher current, its northerly move- 

 ment was retained, and by terrestrial rotation it gradually lost its 

 easterly direction, until, after a long westerly movement, it finally 

 became a south wind. For this frozen wind to gain at once the 

 latitude and level of the plateau of Barbacena, it is now sufficient 

 ... to meet favourable circumstances to extend northwards. . . . 

 Thus we see that for this phenomenon there was needed a rare 

 combination of numerous and fortuitous circumstances over a 

 considerable journey." 



I will next translate a few extracts concerning other meteoro- 

 logical phenomena ; but space prevents my giving more than very 

 short summaries, and excludes my detailing the causes, for which 

 I refer those interested to M. Liais's exhaustive work. 



HAIL. 



" The hailstones are large, very hard, and I have seen them 

 take three or four minutes to melt. In 1862, I observed four 

 falls of hail in November. There are, according to the inhabi- 

 tants, on an average twenty in a year. At Rio de Janeiro falls of 

 hail are rare. I have only known four from 1858 to 1864, of 

 which I saw three ; and two others from 1865 to 1871. The first 

 fall was on February 22, 1859, when there were only a few hail- 

 stones mixed with a heavy storm of rain. Two others were on 

 October 22 and 30, 1863, during heavy storms, accompanied by 

 thunder. The hailstones were lenticular. I measured some, 

 eighteen millimetres in diameter, and one millimetre thick. They 

 produced a general surprise ; and I have seen persons of sixty 

 years of age who never remembered having seen the like. But 

 the fourth fall was the most remarkable. It occurred October 10, 



