282 IFater Supply. 



beneath. If the well or boring were carried deep into the sub- 

 jacent rock and were perpetually flowini^, the water might be 

 cleansed of its impurities ; but those specimens which I have met 

 with and tested have been hopelessly impure. 



Lower in the oolitic series there are instances ot successlul 

 artesian borings. Thus at Bourn, in Lincolnshire, a large supply 

 has been obtained from borings through the Forest marble and 

 Bradford clays, to a depth of about 90 feet, whence the water 

 overflows the surface. The distribution and presence of these 

 day-beds and the fre([uent faults in the oolitic strata are so 

 complicated, that it is imj)ossible to lav down any rules for 

 guidance. 



The same may be said of the lias clays which underlie the 

 oolitic rocks. The marlstone, generally charged with water, 

 which intervenes between the upper and lower lias clays, would 

 seldom yield its water except to wells sunk in the ordinary v/ay. 

 At Chipping Norton the h)wer lias clav was pierced to the depth 

 of 500 feet, in the hope of obtaining water from the underlying 

 new red sandstone formation : the attempt was abandoned at that 

 depth. Again, much the same may be said of the red sandstone 

 formation, which forms so large a part of the surface of western 

 England, though it may and often does yield its subterranean 

 water when deeply pierced. At York water so raised was too 

 much charged with iron and other mineral substances to be of 

 any real value. The well-known salt and other mineral springs 

 in this formation point to the ])robabilitv of their existence else- 

 where. 



As artesian wells derive their supply from deep-seated or main- 

 springs, the existence of such sources of water has, to a certain 

 extent, been anticipated, though it is quite necessary to speak 

 separately of main-springs. 



Maix-sppjngs, 



As the term land-spring is usually applied to sources of water 

 flowing from superficial beds of drift, sand, or gravel, resting on 

 impervious substrata, the term main-spring usually indicates those 

 deep-seated supplies found in the recognised geological forma- 

 tions, such as the chalk, greensands, oolitic, some beds of lias, 

 new red sandstone, and any other stratum into Avhich the water, 

 falling on its surface, will freely sink through cracks or crevices, 

 forming beds of water which rise in these strata till they find 

 vent in valleys and depressions, and so Ibrm the natural perennial 

 sources of rivers, or hidden supplies, which are reached by sinking 

 shafts or wells, whence water is raised by artificial means. 



To advance our knowledge of the presence oi these supplies, 

 the localities and depths at which they may be found, tlieir eco- 



