MR. H. B. WOODWARD ON A WELL-SINKING AT SWINDON. 287 



23. Account of a Well-sinking made hj the Great Western Rail- 

 way Company at Swindon. By Horace B. Woodward, Esq., 

 F.G.S. With Lists of Eossils by E. T. Newton, Esq., E.G.S. 

 (Read March 10, 1886.) 

 (Published by permission of the Director General of the Geological Survey.) 



1. Particular account of Well. 



2. Lists of Fossils. 



3. Remarks on Strata. 



4. Saline Waters. 



5. Fresh Water. 



6. General Conclusions. 



1. The Great Western Railway Company being desirous of obtaining 

 a good supply of water for use in their locomotive and stationary 

 engines at Swindon, determined, in 1883, to sink a well. The spot 

 chosen for this undertaking is on the northern side of the railway, 

 and at the western end of the Company's works. 



Two shafts have been sunk, very close together — one known as the 

 South Well, to a depth of 246 feet, and the other as the Xorth Well, 

 to a depth of 736 feet 2 inches. The details of the strata passed 

 through in the two sinkings, to the depth of 246 feet, are practically 

 the same, the shafts being 8 feet in diameter and sunk the entire 

 depth. The object of the additional shaft was for convenience in 

 pumping and in carrying away the material excavated. The surface 

 of the ground is 329 feet above the Ordnance datum. 



The formations proved in the jN'orth Well are as follows (see sec- 

 tion, p. 296) : — 



ft. in. 



Made ground 8 



Kimeridge Clay 64 1 



Corallian beds 40 1 



Oxford Clay and Kellaways Rock .... 572 9 



Cornbrash 18 3 



Eorest-marble 33 



736 2 



From a practical point of view this well has not been altogether 

 successful ; for, although the promoters did not actually get into hot 

 water, they tapped a supply of luke-warm and very saline water. 



The Corallian beds, which occur between the depths of 72 and 

 112 feet, yielded the first supply of water, which issued at the rate 

 of about 1000 gallons per hour; but neither in quality nor in 

 quantity was it deemed satisfactory. It contained 144 grains of 

 saline matter per imperial gallon. 



Water again was met with at the depth of 730 to 736 feet, 

 rising from the Forest-marble at the rate of about 2000 gallons per 

 hour, and having a temperature of 64° E. This water, unfortunately, 

 proved to be much more saline, containing over 2000 grains per 

 imperial gallon, and was therefore utterly unfit for use in the loco- 

 motive and stationary engines. 



