310 THE CLIMATE OF LOURENQO M AROUES. 



come inland, by preference from the S or SW, and not from 

 the N, also that they do not travel across South Africa from west 

 to east, etc., etc. 



I lack, however, sufficient data for a detailed study of these 

 depressions, and such would not come within the scope of this 

 paper, which I do not intend making too long. 



Wind. 



In Lourenco Alarcjues the hours of calm are very rare, and 

 this fact, combined with the prevailing sea-breezes, contributes to 

 a great extent to make the climate more pleasant. 



From 1909 to 191 2, 24, 2, 29, 61 hours of calm respectively 

 were registered, this being very insignihcant, and not reaching an 

 average of 30 hours per annum. 



The Anemometers at the Observatory are placed over the 

 building, which is situated on very even ground ; for many kilo- 

 metres around there is nothing higher than the 01)servatory 

 itself. 



In Table No. VII, giving the means for four years, one sees 

 that only in a limited number of days is the wind light, that 

 strong winds are even less fre(|uent, and that onlv moderate 

 winds are really very frequent. 



As to the variation of the direction of the wind, it would be 

 an easy matter to foresee, on account of the position of, Loureni:o 

 Marques on the littoral, the very jjronounced influence of the 

 land and sea-breezes. Land breezes make themselves felt par- 

 ticularly from April to August, and not so much in November 

 and December; they begin at about XXIII, and generalh go 

 down after IX, and not later than XT. It is most rare to get 

 wind from the W quadrant after noon, except when there is the 

 NNW hot zvind. 



During the months w'hen this system is well estal)lislied. it 

 is only when the N or S wind blows violently that it does not 

 veer to the W quadrant during the night. 



According to the rule ap])lying to circumstances such as are 

 peculiar to Lourengo Marcjues, the velocity of the wind is higher 

 in the day time than at night ; it is weaker between the hours 

 O and III, and increases steadily vmtil XVI, and a fresh wind 

 prevails until XIX. As will be seen, the velocity of the wind is 

 connected with the variation of temperature, but when the latter 

 decreases, the velocitv of the wind does not usually immediately 

 diminish. 



Two facts shovdd be mentioned : at XI the velocity of the 

 wind generally decreases, and this may be explained by the influ- 

 ence of the land and sea-breezes, as the decrease is more pro- 

 nounced from April to August, and it is at this time that the 

 wind generally changes. The more pronounced decrease in wind 

 velocity from XXI to XXIII is perhaps due to the same cause. 



The rule as to land and sea-breezes being more intense in 

 the months of greater variation of temperature and the smaller 



