ON THE CIRCULATION OF UNDERGROUND WATERS. 69 



As to the Mode of Circulation of Underground Waters. — A few minutes' 

 consideration will show that the supply to a well or bore cannot arise through 

 general percolation through the pores of the walls or internal surfaces of the 

 well or bore. According to Mr. Isaac Roberts's experiments, quoted in your 

 1st Report of 1875, a pressure of 10 lbs. to the square inch, which I suspect, 

 exceeds any hydraulic pressure actiug on the pores of the rocks in any of 

 the wells of which I have returns, gives 4| gallons of water per hour per 

 square foot of sandstone 10 inches tbick, or 108 gallons per foot per diem. 

 If wo take the total area of the surface of the three wells and bore-holes of 

 Messrs. Gaskell, Deacon, and Co., at Widnes, which is the largest well-sur- 

 face, compared with the yield of water, that I have recorded, it amounts to 

 4428 superficial feet, which, with 500,000 gallons per diem, gives 113 gallons 

 per superficial foot per diem, assuming the water to ooze out at the same rate 

 from top to bottom, which is manifestly absurd ; if, on the contrary, we take the 

 Green Lane one recorded in your Report of 1875, p. 123, we find it has an 

 area of only 95 superficial feet of surface and a yield of 817,000 gallons per 

 diem, or 8600 gallons per foot per diem. 



It is tbus evident to me that the rain-water is absorbed generally by the rock 

 at the surface, and that it percolates very gradually to underground fissures, 

 traverses planes of bedding and jointing, and so circulates and is drawn off at 

 the well. It is, in fact, a large rock-filter, with veins and ramifications ex- 

 tending in various directions, which enable us to tap and draw off the supply; 

 and it is this freer circulation than what would take place through homoge- 

 neous rock that enables us to draw in some cases those immense supplies, 

 such as is obtained at Green Lane, of 3,243,549 gallons per diem as a maxi- 

 mum, the average quantity for 1876 being 2,903,712 gallons per diem. 



Source of the Supply : Rainfall. — The enormous aggregate yield of wells 

 in a given area of the New Red has set many speculating as to the source of 

 the underground water, some being unwilling to admit rainfall as a sufficient 

 source of supply for the wells ; consequently ingenious theories have been 

 devised to account for it. Mr. Joseph Boult, to whom I am indebted for 

 much information, does not believe the supply is from surface-percolation ; 

 and Mr. Robert Bostock, an excellent practical geologist, of Birkenhead, 

 believes that sea-water is decomposed by filtration through the rock, and 

 that the water of the sea is the main source of the supply. Unfortunately, 

 when tested, none of these theories will themselves " hold water ; " and 

 whatever difficulties there may be in " surface-percolation," there are, in my 

 opinion, tenfold greater difficulties in any other theories. Again, many 

 Cassandra-like water-prophets cry out that because the water-level is reduced 

 in Liverpool, therefore we are drawing on capital, and are gradually exhaust- 

 ing Nature's storehouse, or rather " store-cistern." A little calculation would 

 show this latter fear to be groundless. 



According to information supplied me by Mr. G. J. Symons, which I append, 

 the maximum rainfall taken by Mr. Briggs at Sandfield Park, near Liver- 

 pool, for 10 years ending 1874, was 34-90, and the minimum 22-64, the 

 average for the 10 years being 30-14. Roughly, 25 inches of rain over a 

 square mile of surface gives a supply of 1,000,000 gallons per diem ; there- 

 fore if we assume that 10 inches are absorbed independently of evaporation 

 (and I think this is not an unreasonable assumption in a fiat absorbent dis- 

 trict like Lancashire), it would take a contributing area of 7-5 square miles 

 to supply 3 million gallons per diem. It must also not be lost sight of that 

 rivers having their sources in other strata — the carboniferous system for 



