The Climate of East London, Cape Colony. 



229 



In view of these differences it will be safer to regard the numbers in 

 the previous Table as more or less approximate ratios. 



The annual incidence of heavy rain is curious. It seems that in 

 May and June more than 10 per cent, of the number of daily falls 

 exceed an inch, whereas in October only 3 per cent, are so great. 

 This confirms for East London what has previously been found for 

 Kimberley, namely, that October differs in the character of its 

 climate from all the other months." 



The Table below gives the direction of the wind, and of the cloud 

 currents, immediately before and after rain in number of times 

 observed, and for comparison the relative frequency of all winds : — 





Normal 



Rain Wind. 



Rain Cloud. 





Wind 



Frequency. 





















Beginning. 



Ending. 



Beginning. 



Ending. 



N 



19 



8 



11 



4 



8 



N.E 



47 



43 



33 



32 



44 



E 



9 



2 



6 



1 



4 



S.E 



5 



3 



3 



2 



5 



S 



16 



5 



7 



22 



28 



S.W 



49 



89 



70 



100 



97 



W 



39 



49 



69 



25 



15 



N.W ... 



22 



7 



7 



2 



1 



We see from this that while the normal frequency of south-west 

 winds is 49 times out of 206, the frequency before rain begins 

 increases to 89 times. In fact, rain simply elongates the normal 

 mechanical resultant in a south-westerly direction. During rain 

 there seems to be a tendency for the vane to shift slightly, pointing 

 more landwards. 



The Tables at the end give in twelve columns, for each day of the 

 year, the following elements : — 



1. The date. 



2. The mean barometric pressure at 32°. 



3. The greatest pressure observed in 21 years. 



4. The least pressure observed in 21 years. 



5. The mean maximum temperature in the shade for the 24 hours 

 ending 8 a.m. of the opposite date. 



6. The absolute maximum. 



7. The mean minimum temperature in the shade. 



8. The absolute minimum. 



* See J. R. Sutton, "An Introduction to the Study of South African Rainfall," 

 Trans. S. A. Phil. Soc, vol. xv., 1904. 



