74 Transactions of the Boyal Society of South Africa. 
following a heavy rain over Kimberley (5 inches in 12 hours) on 
March 20, 1910: — 
TABLE 1. 
Daily Average Deviation of the Horizontal Pendulum to 
THE West. 
March 20 40*4 mm. 
21 37-7 
22 26-3 
23 18-8 
24 14-5 
25 10-3 
This indicates a great depression of the east end of the level, due no 
doubt to the fact that a great deal of the storm water both ran directly off 
the ridge on which Kimberley is built as well as percolated downwards to 
the lower land eastwards, thus increasing the load and depressing the level 
on the side where it settled. Later on there was a gradual recovery. 
The pendulum, being reset to somewhere near its first value, recorded the 
following daily average readings : — 
TABLE 2. 
Daily Average Deviation of the Horizontal Pendulum to 
the West. 
March 26 
43-2 mm. 
April 3 
April 11 , , 
27,,, 
,,,43-1 
4 
44-7 
12 
...56-1 
28... 
41-2 
5.. 
44-4 
13,,, 
.,,56-3 
29 
40-8 
6,, 
, 44-6 
14 
56-4 
30 , 
41-1 
7, 
,...47-3 
15,.. 
.,57-2 
31, , 
41-2 
8 
48-4 
16... 
.,,58-6 
April 1 . . . 
42-8 
9 , 
49-8 
17,,, 
, 60-1 
2 
43-7 
10 , 
., 51-5 
18 
...60-4 
It appears, therefore, that the movement of the pendulum to the 
east lasted ten days, the recovery to the west taking at least twice 
as long. 
To show the effect of the passage of a barometric depression upon the 
level, forty-four fairly typical and well-defined depressions were selected, 
and the average barometric pressure on five successive days — the third of 
