302 MK. H. B. WOODWARD ON A WELL-SINKEN^G AT SWINDON. 



sufficient for every purpose." From experiments made by Dr. 

 Gibbes, this water was found to hold in solution " the same salts as 

 the other well, and in still larger proportion" *. 



At Holt, between Melksham and Trowbridge, saline waters were 

 discovered towards the close of the 17th century in sinking a well. 

 An account was published by H. Eyref, who states that the water 

 contained " mixed salts," in the proportion of 3 drachms, 1 scruple, 

 and 19 grains in 1|- gallons of water ; no particular analysis, how- 

 ever, was given. The details of the strata passed through were 

 noted by the Eev. Mr. Lewis as follows : — 



^ 



" After they had passed the upper turf they came to a blue Clay, which 

 held about 3 foot ; then they met with a yellow, brittle Clay, very much 

 like ochre, used by painters, about 2 foot in thickness ; and next with a 

 loam of a looser texture, which sparkled with a kind of talc, called by 

 the naturalists Selenites, and was intermixed with yellow ochre. . . . 

 " Below this, at about 10 foot deep, they came to a bed of stones, of a/ 

 2j \, large size, and very hard texture [Septaria] . . . 



S, ^ f "Here the springs come in, and below this the Clay was darker 



% "^ I coloured, and interlaid with small shells of the Oyster, Escallop and 

 ;^ g -^ Muscle kind, and with a few Belemnites curiously shaped. Here they 

 g Ph I met with stones of a very close texture, which when washed seemed to 

 Mj \^ be nothing but a mass of shells jumbled and embody ed together"]:. 



In connection with this subject it is interesting fo note that 

 saline or brackish water was also met with in a well made at 

 Trowbridge (March 11, 1870, not finished). The well was sunk 

 160 feet and bored 40 feet " into Lias." The water was found to 

 contain the following ingredients : — 



Total solid impurity (in parts per 100,000) 144-34 



Chlorine 36-70 



The following appears to be the only account of this well at 

 present published : — 



" In sinking the shaft a salt spring was tapped and afterwards 

 stopped out, but we were informed that some water came in at 

 about 20 feet from the surface. Our analysis, given at page 105, 

 shows the water to be excessively hard, and to contain a considerable 

 proportion of common salt (6 lbs. in 1000 gallons, 3oz. in this 

 volume of water being about the usual proportion in good potable 

 water), besides a rather large proportion of organic elements " §. 



'No details of the strata are given. The well was probably com- 

 menced in the Cornbrash (if not Oxford Clay), and if carried into 

 the Lias it shows a great diminution in thickness of the Lower 

 Oolitic strata. It is very likely, however, that the term " Lias "^ 

 was that used by the well-sinker, and the well was simply carried 

 through the Forest-marble into the Great Oolite. 



* The Melksham Guide, 1815. Britton and Brayley, ' Beauties of Wilt- 

 shire,' vol. iii. p. 221. 



t A brief Account of the Holt Waters in Wiltshire. 12mo. 1731. 



+ Phil. Trans, vol. xxxv. p. 489 (1728). 



§ Sixth Eeport of *he Eivers Pollution Commission, pp. 104, 105. 



