Water in deep 
‘wells in 
higher district 
rise first. 
Yield of strata 
constant under 
same con- 
ditions, 
18 
higher parts of the district is considerably lower than at 
the lower parts of the same district, it follows that the 
amount of evaporation would be less in the higher 
districts, and therefore the quantity of rain percolating 
‘the ground would be proportionately greater in the 
higher districts. The Author succeeded in establishing 
a Meteorological Station under the care of the late 
Mr. W. Foster, of Henley, Chelsham, at an elevation of 
610 feet above ordnance datum, which was kept going 
for 33 months in the years 1881, 1882, and 1883. In 
this time Mr. Eston calculated the diminution of 
temperature in ascending the North Downs was one 
degree for every 231 feet of elevation. 
Owing to the very much larger amount of rain which 
falls on the higher district, and its less liability to waste, 
it has been found that the water in the deep wells in 
the higher parts of the district always begins to rise 
before the water in the wells in the lower part of the 
district. This may appear rather curious to some 
persons that the top of the basin should begin to fill 
before the bottom, but when it is considered that a much 
larger amount of water percolates into the ground in 
the higher district, and that there is considerable 
resistance offered by the strata to the water flowing 
rapidly away from tle upper part of the basin, it is 
sufficient to account for what really occurs which 
enables the Bourne flow to be predicted some con- 
siderable time before it breaks out. 
It may be taken as an absolutely ascertained fact. 
that with the same height and fali of the water in the 
ground the quantity of water yielded by a particular 
area will always be the same, and knowing the height 
to which it is necessary for the water to rise before a 
Bourne will make its appearance, this height may pro- 
