172 OBSERVATIONS ON 



direction from the table land in the neighbourhood of 

 Charter House and Priddy. And, again, on the north slope 

 of the Mendips, at Banwell, we have another instance of 

 one of these large outlets of the drainage area of the Men- 

 dips, probably from a south-east direction. This outlet, in 

 the middle of the Banwell pond, I have myself gauged in 

 1885, and the uprush of water through an inverted cone, 

 which is very discoloured after heavy rains and throwing 

 up a constant collection of sand and grit and shell or 

 limnsea, is equal to a quantity of 5-10 million gallons per 

 day, according to rainfall. 



There are further illustrations of springs in the neigh- 

 bourhood with which we are more familiar, viz., in the 

 spring issuing on the south side of the Avon just below 

 the Suspension Bridge. This has its gathering ground 

 doubtless in the south-west area of the Carboniferous 

 Limestone around Failand in the outcrop of Mountain 

 Limestone superposing the Old Red Sandstone formation. 

 This is an intermittent spring, which flows about half a 

 million gallons per diem in wet seasons, sinking to nil in the 

 summer, as in 1887-1893, when it stopped entirely, and is not 

 perennial like the Sherborne spring before mentioned, which 

 I have never known lower than one million gallons per day. 

 Again we have the Hotwells spring and Buckingham 

 and Hichmond springs, over the site of which the original 

 Waterworks Company sunk wells to supply parts of Clifton ; 

 this is a case where the evidence of water-bearing strata 

 is augmented by sinking deeper for the purpose of in- 

 creasing or opening out the yield of underground water. 



With reference to sinking and boring wells, I have be- 

 fore, in connection with our local Engineering Society, 

 treated upon wells sunk in the New Red Sandstone ; but 

 I thought it would be interesting to members to see some 



