The Rainfall of South Africa. 
377 
Section (c). — There are only 2 cases, 1 followed by rain and 1 by dry 
weather. Eainfall was only 0*06 in. 
Prediction for Division. — Dry weather. 
SUB-GEOUP (L). 
This is an important condition ; it can be brought about by an advan- 
cing winter type depression, or by one pushing down from the north after 
the centre has passed Clanwilliam. It can also happen when an existing 
depression to the south surges back by deepening. When L'Agulhas is 
actually lowest and the glass is low, a winter type depression is sure to be 
affecting us and rain is almost certain, but when the glass is either mean 
or high a depression from the north is more than likely the cause of the 
disturbance, when rain is not likely to fall. With the barometer lowest at 
the Royal Observatory or Clanwilliam, summer type conditions may be 
prevailing and rain not probable. 
DIVISION (1). 
Section (a). — This condition came about upon 27 occasions, and dry 
weather followed only 5 of them ; wind was generally from a westerly 
direction. Looking at these 5 cases I find that each was in connection 
with a winter type depression, and that rain would have been predicted. 
In 4 cases rain did come as an accompaniment to the depression, but not 
under 48 hours. 
Prediction. — Wet weather. 
Section (b). — Here we have 11 cases with westerly winds prevailing ; 
only on 3 did rain follow, in 1 instance being only 0'02 in. 
Prediction. — Dry weather. 
Section (c). — This happened upon 14 occasions, and rain followed 4 of 
them ; no rain would have been looked for as following any of these 4 
cases. 
Prediction. — Dry weather. At the same time the glass and 
sky should be carefully watched, to see if there is any indication 
that the yielding pressure is due to an advancing winter type 
depression, when slight rain is probable. 
DIVISION (2). 
Section (a). — 2 cases ; dry weather followed. 
Section [b). — 2 „ ,, ,, ,, 
Section (c). — 4 ,, „ ,, ,, 
Prediction for Division. — Dry weather. 
