356 Reviews—Daglish and Forster, 
few formations in British geology the water-bearing properties of 
which are so remarkable. Previous to 1818, when the Durham 
Coal-measures were wrought only to the west of the Magnesian 
Limestone, the quantity of water in that rock and the underlying 
‘Lower Red Sandstone’ does not seem to have been suspected; but 
in the first attempt to win coal below the limestone, near Hetton-le- 
Hole, such immense bodies of water were encountered on reaching 
the ‘Lower Red Sandstone,’ that the shaft had to be abandoned. 
The skill of the northern engineers, of course, ultimately prevailed, 
both here, and where other pits were subsequently put down, but 
only after severe struggles,—a first and second shaft having some- 
times to be given up as failures before the Coal-measures could be 
reached ; and 1,000, 2,000, and even 10,000 gallons of water a 
minute had sometimes to be pumped from the shafts in order that 
the sinkers might work. 
But what is so great an evil and such a source of expense to the 
coal-owner has been turned to a great good, and a source of wealth, 
to the inhabitants and capitalists of the district; for, availing them- 
selves of the knowledge so dearly bought by the former, the latter 
have sunk deep wells to these subterranean reservoirs, and so 
obtained a plentiful supply of pure water. The towns of Sunder- 
land, South Shields, Jarrow, and Seaham, besides numerous villages, 
are all furnished with water in this manner. The aggregate supply 
at these places, combined with the quantity taken from the same 
sources by private wells, is probably at the present time very little 
under 5,000,000 gallons daily. : 
The water is usually met with in the form of powerful feeders ;— 
a feeder being a joint or fissure filled with water. Messrs. Daglish 
and Forster suppose that a very slight supply is derived from the ~ 
percolation of water through the mass of the rock itself ; and this 
undoubtedly holds good, as the question is practically viewed by 
them. But there is just as little doubt that water percolates more 
or less the whole mass of the Magnesian Limestone and the under- 
lying Sandstone, and that below the water-level these deposits are 
kept thoroughly saturated according to their capacities of saturation. 
The capacity of these rocks for retaining water varies. Some of 
the crystalline varieties of the limestone absorb very little. Others, 
less crystalline in character, hold 3°45, 6-0, 13:18, 14°87, and even 
17:0 lbs. of water to the cubic foot. The sandstone varies less in 
this respect ; 10 lbs. of water (or a gallon) to the cubic foot being 
about its usual point of saturation. With the lower strata of the 
limestone and the sandstone thus saturated, all cavities and empty 
spaces in their mass naturally become filled with water. Open 
joints and fissures, of which there are many, more especially serve 
as receptacles for it ; and from their wide ramifications they form 
great subterranean reservoirs ready for the use of man—or for his 
annoyance, as the case may be. They, moreover, not only serve as 
natural reservoirs, but also, from the extensive areas offered by their 
walls as surfaces of collection, as a means for the rapid accumulation 
of supplies from the main stores of water held in the mass of the 
rock. 
