108 
Transactions of the Royal Society of South Africa. 
At the foot of Table TV will be found the total rainfall by months ; from 
which we deduce the average fall per hour of rain given in the following line. 
Rain tends to fall heaviest in February. It falls lighter in October than in 
any other of the seven months September to March. This is of course due to 
the peculiarity of Kimberley rain — as yet unexplained — that a fall exceeding 
an inch a day in October is uncommon. The only heavy falls per twenty-four 
hours from 1897 to 1919 have been: In October, 1902, 1 05 in. ; in October, 
1906, 1-56 in. ; in October, 1915, 1-14 in. ; in October, 1918, 1-17 in. 
There are records of heavier falls than these, in one day, in most of the 
other months. 
The following table shows the monthly percentages of — 
(1) day thunderstorms to night ones ; 
(2) day rain hours to night ones ; 
(3) day rainfall to night ; 
"day" being counted from 8 a.m. to 8 p.m., and " night" from 8 p.m. to 
8 a.m. 
Thunderstorms 
Eain Hours 
Eainfall 
(%). 
(%). 
(%)• 
January . 
371 
125 
148 
February . 
361 
122 
159 
March 
230 
112 
128 
April 
236 
109 
107 
May 
336 
94 
101 
June 
55 
87 
99 
July 
100 
62 
111 
August 
59 
67 
63 
September 
124 
80 
158 
October . 
356 
142 
244 
November . 
439 
190 
296 
December . 
546 
163 
198 
Year 
306 
117 
152 
We see from this that it rains more often by day in the summer at 
Kimberley, and more often by night in the winter. But the total fall in the 
winter is on the whole about the same night or day ; so that with the 
exception of August the rate of fall is always greater during the day. At 
midwinter, also, thunderstorms favour the night hours. 
On the average of the year, for every hour of night rain the fall is '044 
inch, and there is '235 hour of thunderstorm ; while for every hour of day 
rain the fall is '057 inch, and -616 hour of thunderstorm — not forgetting 
that the hour of rain is not the duration, whereas the hour of thunder- 
storm is. 
