Influence of 
rain on Bourne 
flows. 
22 
It should be observed that with regard to the 
influence of rain on a Bourne flow, that it is the rain 
that falls immediately preceding a Bourne flow which 
really governs its future appearance and volume. This 
is very clearly seen from the fact that so great an 
authority on Bourne flows as the late Mr. Cuthbert 
Johnson, who stated clearly that there could be no 
Bourne flow in 1877, having regard to the fact that 
there had not been 30 inches of rain at Croydon in the 
preceding year, and that it was only when 30 inches 
of rain fell during the preceding year that a Bourne 
flow at Croydon occurred. If, however, rain is tabu- 
lated over the six months from October in one year to 
March in the following year, it will be seen that it 
corresponds with the volumes of the Bournes which 
have occurred. 
The following figures give the rainfall at Croydon 
between October and March for all the years of Bourne 
flows between 1865 and 1904. 
