WATER-BEARIXG STRATA. 335 



The debris was afterwards raised by a miser weighing 1| 

 tons, with flap valves above which the debris was forced, 

 and so drawn up to the surface. 



The depth of the wells was 100 feet, costing £5 14s. 6d. 

 per foot for each well. 



The chalk being of a friable nature, it was found necessary 

 to line them with tubes of mild steel, 1 inch less in diameter 

 than the wells, and | inch thick. 



These were made in 6-ft. lengths in two segments, with 

 butt joints, and inside covering strips and flush outside ; holes 

 were left in the plates at side to allow of free ingress of 

 water. 



The tubes were lowered into place by their own weight, 

 and the cost of lining was £780. The total cost of the 

 bored wells was £1,700 ; one of equal area sunk in the 

 ordinary way would have cost £2,500. 



The hardness of the waters in the chalk is 16° to 18^, 

 mostly temporary. 



New Red Sandstone Wells. — The New Red Sandstone 

 formation both in the Keuper and Bunter series is always 

 looked upon as an area which can be relied upon for yielding 

 supplies of water of abundant and good quality. 



I do not know that any computation of the area has been 

 made, but taking it approximately from the Geological Map 

 of England and Wales, it covers an area of about 12,000 

 square miles, chiefly in England, and situated mostlj'- in the 

 Midland, North Western, and Western Counties ; and if 

 that covered by the Lias (which the Sandstone possibly 

 underlies to a large extent) be taken into account, the area 

 would be increased by 6,000 square miles. 



The New Red Marls and Sandstones of the Keuper are 

 geologically situated in the Trias formation, and immediately 

 under the Lias and Rhoetic or Penarth beds. 



