MH. H. B. WOODWAKT) ON A WELL-SINKING AT SWINDON. 303 



Again at Road, between Trowbridge and Frome, a mineral water 

 was discovered more than 100 years ago. An account of it was pub- 

 lished by S. Williams, who stated that it contained " steel, sulphur, 

 and natron," but no analysis was given*. The water was probably 

 obtained from the Cornbrash or Forest-marble. 



Important evidence of saline water is that furnished by an artesian 

 well made in 1832 at St. Clement's Brewery, Oxford. Attention 

 has been directed to this water by Prof. Prestwich. The well was 

 carried to a depth of 420 feet, through Oxford Clay 265 feet, and 

 Great Oolite, &c., below ; but no detailed account of the strata has 

 been preserved. Chloride of sodium was most abundant in this 

 water, and sulphate of soda came next in quantity t. (See analysis, 

 p. 299.) 



The conclusions to be drawn from these records are that in certain 

 localities, as at Melksham and Trowbridge, at Swindon, and at St. 

 Clement's, Oxford, where the Great Oolite series has been reached, 

 the prevalent salt is chloride of sodium ; and that while saline water 

 has been found at higher levels in the Corallian beds, the water 

 obtained is less saline, and the prevalent salt is in several cases 

 sulphate of soda. 



The occurrence of the saline water is suggestive of the proximity 

 of Triassic rocks, as remarked by Prof. Prestwich in connexion with 

 the well at St. Clement's, Oxford. He points out that the Chelten- 

 ham waters, which contain much chloride of sodium, issue from 

 the Lower lias, " but as the upper beds of the jS'ew Red Sandstone 

 crop out a few miles west of Cheltenham, and pass under the Lias, 

 geologists have concluded that the wells traverse the Lias and reach 

 the New Red, and that it is from those beds that the saline water 

 comes." Prof. Prestwich concludes " that the water at St. Clement's 

 has its origin in the JSTew Red Sandstone, and not in the Oohtic or 

 Liassic strata, as would otherwise, from the depth of the boring, be 

 the natural inference. If the water were from the Oolitic strata 

 we should expect to find it much purer, and its solid matter to 

 consist chiefly of carbonate of lime ; if from the Marlstone or Lias 

 to be more ferruginous and calcareous." 



Curiously enough the water of the new Swindon well has yielded 

 no carbonate of lime, very little sulphate of lime, and very little 

 ferruginous matter. Moreover the saline waters found in the dis- 

 trict vary very considerably, so that if the mineral matter be 

 originally derived from Triassic rocks, the water is diluted and 

 modified by other waters with which it has come in contact in 

 rising towards the surface. 



Concerning the position of the Triassic rocks we may make a few 

 remarks. The deep boring at Signett, south of Burford, in Oxford- 

 shire, is about seventeen miles north of Swindon, and there the 

 following strata were penetrated : — 



* An Experimental History of Koad Water in Wiltshire. 8vo. London, 

 173L 



t Ashmolean Soc. 1876. 



