32 DE RANCE : UNDERGROUND WATERS IN LINCOLNSHIRE. 
of water. The chief motion of underground water takes place along 
cracks and fissures in underground defined channels, rather than 
through the pores of the rock. Two very adverse conditions arise 
from this: First, that when water passes through fissures, and not 
through pores of the rock, the natural process of filtration is not 
exerted. Second, that in works of this class (as will be seen in the 
chalk) there is an unsatisfactory element of chance as to whether 
any particular boring may intercept a fissure along which water is 
travelling or capable of travelling. In the case of the Lincolnshire 
Oolites, as they are carried by the dip under overlying Oolite and 
Cretaceous rock under the German Ocean, there is no probability of 
the beds appearing at the margin under the sea, and consequently 
the water is passing under the overlying strata, though fully charged 
with water previously absorbed, and an artesian pressure which 
varies in amount according to whether the head of water rises after 
rain or sinks after drought, as is seen in Dunholme Boring, which 
increases in flow after rain, the rain in question having been absorbed 
several miles to the west. This ready response to rainfall is a 
most unsatisfactory element in the Lincolnshire Oolite, and is well 
evidenced by the great variability in the springs gauged by Mr. 
Teagne, C.E., at Welton, running in — 
August, 1878 ... ... ... 105,000 gallons 
June, 1887 ... ... ... 168,000 „ 
June 15, 1891, after heavy rainfall ... 2,800,000 „ 
July 29, 1891 ... ... ... 759,600 „ 
Sep. 16,1891 ... ... ... 493,560 „ 
The whole of the rainfall absorbed by the Lincolnshire Oolite 
is thrown out as springs, which act in direct response to the rainfall, 
and any wells or artesian boreholes to obtain a large supply will have 
to pump at a greater rate than the water can naturally flow out at 
the springs at the high level, and it is doubtful whether the pumps 
could do this, unless they should be fortunate enough to be placed in 
a line of natural fissure. Regarding the springs as interest and the 
water stored under the clay area as capital, it follows that no water 
can be permanently pumped beyond the capacity of the springs, and 
then only at their expense. 
