1042 REPORT—1885. 
large supply of water from the Chalk, galleries being driven (in one case to the 
length of 800 feet) at about low-water level, so as to cut the fissures and intercept 
the water on its way to the sea. 
The whole of the works (shafts and galleries) are in the White Chalk, with but 
few flints in the bedding-planes, but with many oblique layers along joint-planes. 
The supply comes chiefly from a few powerful springs, and, though small contribu- 
tions issue between these, it is noteworthy how far a tunnel has sometimes been 
driven before reaching a fissure of large yield. Under these circumstances borings, 
or even shafts, might have failed to yield a large supply. 
The roof of the north-eastern gallery is throughout of one bed, rarely needing 
support, a thin brittle layer of flint at its base being cleared away. 
