j 1 j. THE ANTARCTIC. 



the southern quadrant occasionally bring clear weather 

 interrupted by snowstorms, whilst the northern winds 

 generate dense fogs, and Bruce says the same thing. 



Most commonly precipitation takes the form of snow, 

 rain is comparatively rare, and dew and hoar frost make 

 considerable contributions. Ross noticed on 31 per cent, 

 of the days some rainfalls in form of passing showers at 

 a latitude south of 70° S. ; persistent rain on the 11th 

 of February, 1842, at 70° 6' S. and 178 18' W., and the 

 last rain altogether on the 29th of January, 1841, in yy° 

 47' S. and 1 76° 43' E. Wilkes and Dumont d'Urville 

 also experienced heavy rainfalls, but at the considerably 

 lower latitudes of Wilkes Land and Louis-Philippe Land. 

 Hail, on the other hand, occurs but rarely ; Wilkes alone 

 reports two instances — he mentions also sleet, and draws 

 special attention to the important part played by the 

 formation of dew. On one occasion he observed that 

 during a fog a crust of ice nearly a quarter of an inch in 

 thickness had been formed within a few hours. 



The snowfall is of far more importance in Antarctic 

 regions than all the other forms of precipitation, since 

 it is even in the open sea by no means restricted to the 

 winter season. Ross observed in the southern summer 

 of 1840-41, south of latitude 70 S., that it snowed on 

 57*6 per cent, of the days of observation ; in the summer 

 following on 62 per cent, of the days, and finally in the 

 summer of 1842-43, when he was east of Graham's Land, 

 on 68*8 per cent, of the clays. The form of the snow- 

 crystals depends, of course, on the temperature, yet 

 full-shaped large flakes of the familiar crystals apparently 

 occur but rarely ; most commonly the snow assumes the 

 shape of small fine ice-needles. These, no doubt, pre- 

 ponderate on land, as seems proved by the occurrence 

 of snow-drifts at Mount Haddington and Wilkes Land, 

 as well as the formation of snow-mounds on Adelie Land, 

 and a glance at the low temperature fully explains this. 



