THE CIRCULATION OF UNDERGROUND WATERS 393- 



r/*e Circulation of Jjnderriround Waters. — I'irenty-Jirst Report of the 

 Committee, consisting of Dr. E. Hull (Chairman), Sir DoUGLAS- 

 C4ALT0N, Messrs. J. Glaisher, Percy Kendall, Professor G. A. 

 Lebour, Messrs. E. B. Marten, G. H. Morton, Professor Prest- 

 wicH, Messrs. I. Roberts, Thos. S. Stookes, G. J. Symons, 

 C. Tylden-Wright, C. Wethered, W. Whitaker, and C. E. 

 De Rance {Secretary). (Drawn up by C. E. De Range.) 



Appexdix. Second List of Works. By W. Whitaker .... page .S94 



YoTTR i-eporter has not received any reports from the Corresponding- 

 Societies since last year's meeting, but he has good reason to believe that 

 valuable results have been collected, and locally published. These will be 

 doubtless of great local value, and it is a source of satisfaction to see that 

 the work originated by the Committee is likely to be permanently carried 

 on by the local societies on the lines initiated by the British Association. 

 Your reporter, however, would again point out that the collection of 

 sections and details of water supply, by some central body, would be of 

 great value to engineers, contractors, and others, who have neither time 

 nor opportunity to seek the records of the various provincial proceedings, 

 and it appears desirable that it be a suggestion to the Corresponding 

 Societies that they annually send up the details they have obtained to the 

 offices of the Geological Survey of the United Kingdom, 28 Jei-myn Street,, 

 London, where a section-book is now kept, and every facility daily given 

 to those seeking information. 



Your i-eporter has not received any information from any member of 

 the Committee during the past year, and therefore thinks it unadvisable 

 to do more than present this formal report, without appendices of infor- 

 mation personally collected by himself, as has been done on several previous; 

 occasions. 



This being the final Report, it may be, in conclusion, advisable to state- 

 that the Committee have had the same chairman and secretary during the 

 whole of their twenty-two years' labours, and they have arrived at the- 

 following general results, some of which are self-evident, but it is necessary 

 to state, through simple conditions, not always universally understood. 



1. The source of all water supply, whether in streams, wells, or natural 

 springs, is the I'ainfall falling on the area, or that adjacent to it. 



2. The quantity of water to be obtained under all three heads is that 

 annually falling, less the quantity evaporated, and less natural loss through 

 retention after natural filtration. 



3. The quantity of underground water to be obtained in sandstones- 

 and grits is governed lay the cubic content of the interspaces between the- 

 grains ; the larger the spaces, the greater facility for the storage and pas- 

 sage of water, coarse grits amounting to 12 inches of the annual rainfall. 



4. In calcareous rocks, as Carboniferous and Magnesian Limestones,, 

 oolitic calcareous rocks, and Chalk, the grains are exceedingly small, the 

 spaces almost microscopic, and the passage of water through the rockr 

 exceedingly slow, but waters so passed are naturally and eftectually 

 filtered. But in rocks of this class open spaces, following lines of joint, 

 faults, and other planes of weakness, constitute fissures and caverns, 

 through which water flows freely in defined channels, as on the surface,. 



