394 REPORT— 1895. 



and, like it, is not subject to natural filtration, and, unlike it, has not 

 the advantage of the purifying effect of sunlight on its passage. 



5. When porous rocks of different characters are separated by thin 

 beds of impermeable material, it is often possible to ol)tain several classes 

 of water from one well, suitable or unsuitable, as the case may be, for the 

 brewing of ale or stout, the dilution of spirits, or the exigencies of the 

 wool or the indigo dyeing trades. 



6. Where wells are pumped at the same daily rate without ajjstracting 

 what the late Mr. Hawksley called ' water of cistonage,' the hardness is 

 reduced after a year's pumping, and this remains stationary over proved 

 periods of forty years. If the pumps are lowered, and the apex of the 

 'inverted cone' be placed still deeper beneath the mean sea-level, the 

 width of the base of the cone is extended, and a new concentric circle of 

 supply is added to the contribution ground ; the water then hardens for a 

 time, but after the soluble salts have been pumped out the degree of hard- 

 iiess remains constant as before. 



7. Faults in porous rocks of whatever thickness, which were originally 

 overlaid by porous rocks, no matter how great their throw may be, are no 

 obstacles to the passage of underground water. 



8. Where the same are, or have been before subsequent denudation, 

 overlaid by impermeable material, the fissure of the fault is filled with 

 irnpermeable material, and it forms a natural puddle trench sej^arating the 

 district into distinct watertight zones. 



9. Where faults of the latter class exist, and tlie area on one side of 

 the fault joins the sea, and a quantity of water is annually abstracted, 

 exceeding the quantity absorbed by rainfall, the excess is derived from 

 the sea, a reversal of the underground current takiiig place ; and as this 

 goes on the rock becomes surcharged with salts, and can no longer act as 

 a filtering medium, and the water pumped daily approximates more and 

 more to the sea water from which it is derived. 



10. Engineers and architects, in many cases, do not realise the danger 

 of placing public pumping stations where the area of supply includes 

 sewage farms and objectionable trade refuse. It is exceedingly desirable 

 that the officials of the Local Government Board should have their atten- 

 tion strongly drawn to this important matter. 



11. This report is adopted by the Committee: they approve of the 

 suggestion of the reporter, that the digest of the previous reports he has 

 prepared be offered to the Geological Survey of England and Wales for 

 publication, and they recommend that, .should this offer be declined by 

 the Survey, the digest l)e dealt with by its author as he may find expe- 

 dient, and they recommend that in either case all blocks and plates used 

 in the previous reports be placed at the recorder's disposal for the purpose 

 of reprint. 



APPENDIX. 



SECOND CHRONOLOGICAL LLST OF WORKS REFERRING TO UNDER- 

 GROUND WATER, ENGLAND AND WALES. 



By W. Whitaker, B.A., F.KS., F.G.S., Assoc.Inst.C.E. 



Since the publication of the list in the Thirteenth Report of the Com- 

 mittee, which ended with the year 1887, 37 additional titles for the years 

 1819 to 1887 have come to hand, of which 2 are different versions of 



