308 MK. H. JB. WOODWAKD 01^ A WELL-SINKING AT SWINDON. 



of the Trias disappeared from north to south. He also pointed out 

 how the thickness assigned, from calculation, by the Geological Sur- 

 vey in a published section, to the Jurassic beds near Swindon pre- 

 cisely agreed with the facts now disclosed. From the ascertained 

 composition of saline springs in various formations, he showed that 

 the water at Swindon was much less salt than the brines of the 

 Keuper marls, and less so than those of the Coal-measures. Mr. 

 Mylne was making a boring about three miles from Swindon, and 

 the information thus obtained would be a useful addition to that in 

 the present paper. 



Mr. Mylne said that the boring just referred to by Mr. De Eance 

 was commenced at the bottom of a shaft in the Cretaceous beds, of 

 the thickness of which he gave some details. The Portland Sand 

 was wanting, and the Kimeridge Clay was not completely bored 

 through. 



Prof. Maskeltne said that the country was well known to him, 

 and that in several wells near Swindon saline water was found, and 

 he instanced one case near Purton where traces of iodides had been 

 met with. The abundance of gypsum in the Kimeridge and Oxford 

 Clays explained the abundance of calcium sulphate. He believed 

 the water in the part of the Swindon well where the Coral Rag 

 was penetrated would be improved by pumping, and cited instances 

 of good water having been procured from the Coral-Rag beds in 

 the neighbourhood by sinking through the Kimeridge Clay. The 

 head of the Thames is an instance of a beautiful spring derived from 

 beds fed by the water percolating the upper part of the Great Oolite 

 north of Cirencester and Tetbury. 



Mr. H. B. WooDWAUD, in reply, said that for many months 

 pumping had been resorted to at Swindon without success in ob- 

 taining better water. After pumping had been discontinued, the 

 water from the lower strata gradually rose to within about 25 feet 

 of the surface. 



