COUNTY RAINFALL. 8 
Derby and east of Chesterfield at least) have an annual average 
rainfall of less than 30 inches, but more than 25, and that the 
amount of rain increases fairly regularly towards the north- 
west and north. It probably exceeds 35 inches everywhere 
north-west of a line drawn through Dronfield and Matlock, and 
does not probably fall short of 40 inches in any part of the 
County lying North-west of a line drawn from Buxton to near 
Sheffield. It is probable that average falls exceeding 50 inches 
in the year occur at several points in the high ground; but it is 
unlikely that so great a rainfall as 60 inches is reached. 
The distribution of the rainfall thus sketched is arrived at 
solely from the consideration of the actual amounts measured at 
a number of stations, and it is found to shew a close relation- 
ship to the physical features of the land. The area within which 
the rainfall exceeds 40 inches contains all the highest land in the 
County; and as the hills sink southward, eastward and westward 
to the Central Plain of England, the mean annual rainfall on 
their slopes diminishes steadily. Again, as might be expected 
from the fact that the prevailing rain-bearing winds come from 
the south-west, the western slopes are found, as an almost invari- 
able rule, to be wetter than the eastern. 
In this relation it is interesting to notice how all the rivers 
radiating from the southern extremity of the Pennine Heights 
derive their waters from a narrow region of high rainfall, and 
distribute them broadly over the plain. It is natural also that 
the ring of manufacturing towns on the New Red Sandstone 
plain encircling the hill country should derive their water supply 
from the unpeopled uplands which bring down the moisture borne 
by the winds from the Western Ocean. 
In conclusion, attention may be directed to the average distri- 
bution of rain throughout the months of an average year at two 
typical and contrasted stations, situated just beyond the county 
boundary in the south and in the north. 
