XX Proceedings of the South African PUilosophiccil Society. 



An examination of the 44 cases in which the wind was E.'ly 

 at Port Nolloth showed that the simultaneous wind at O'okiep was 

 N.E. 14 times, E. 12 times, N.W. 5 times, N. 3 times, S. 

 3 times, and S.W. twice, while it was calm there on 5 occa- 

 sions. These winter N.E.'ly or E.'ly winds at O'okiep are cold 

 when blowing over the plateau as far as Klipfontein, situated on 

 its western edge, at an elevation of 3,004 feet (railway measure- 

 ment). They are experienced as hot winds at Anenous, 6 miles 

 further west {i.e., 48 miles from Port Nolloth), at the base 

 of the plateau, at an elevation of 1,770 feet, where they blow at 

 times wdth almost hurricane force, occasionally filling a railway 

 cutting with drift sand, and blocking traffic. This wind may 

 increase in temperature the further west it blows, culminating at 

 Port Nolloth, or it may die out as a hot w^ind before reaching there. 

 These E. winds may continue for a few hours, but mostly last two 

 or three days at Port Nolloth, while the N. E.'ly and E.'ly winds at 

 O'okiep may prevail for weeks. 



Mean barometric pressure during these winds is found to be 

 relatively high at both places ; the observers stated that at O'okiep 

 the barometer usually rises with this wind, and commences to fall 

 before the wind blows out ; while at Port Nolloth the reverse 

 usually occurs, that is, the barometer falls with E. wind and rises 

 before the wind blows out. A comparison of the barometric 

 readings during these E. winds with those of the preceding days 

 shows that this does occasionally occur, but also shows that there 

 may be [a) a simultaneous rise or fall at both places ; {h) rise at 

 Port Nolloth, fall at O'okiep ; (c) a steady barometer at O'okiep, 

 with fall at Port Nolloth. The mean temperature at 9 a.m. for the 

 nine months was 55*8° at Port Nolloth and 63-7° at O'okiep. This 

 state of the relative temperatures w^as reversed in June-August, 

 especially in July, when Port Nolloth had a mean temperature of 

 4*1° E. above that of O'okiep. This reversal is due to the hot E. 

 winds which may start to blow during day or night, and actually 

 raised the temperature to 83*2° at 9 a.m. on one occasion. Another 

 reading gave dry bulb, 78-2°; wet bulb, 59*3"; dew point, 52*3°; 

 relative humidity, 40 per cent. On the same day the observations 

 at O'okiep were : dry bulb, 48'0° ; dew point, 37*7° ; humidity, 

 67 per cent. 



When the E. wind at Port Nolloth has a force of only 1 on the 

 Beaufort scale of 0*12 the temperature there is, with few exceptions, 

 lower than at O'okiep, but when it is 2 or more, the temperature at 

 Port Nolloth is the higher. 



These E. winds at Port Nolloth arc usually succeeded by N.'ly or 



