208 
POPULAE SCIENCE EEVIEW. 
level than the well. The importance of all these conditions 
being present can hardly be better illustrated than by a re- 
ference to the unsuccessful experiment of the well on the 
Southampton Common^ alluded to above. The permeable 
stratum upon whose water supply reliance was placed was the 
Upper Green Sand^ between the Chalk Marl, and the 
Gault, both of them impervious to water. Although the 
outcrop of this formation is not large, being confined to the 
margin of the irregularly shaped oval basin which the chalk 
forms in this district, it was considered sufficient to supply the 
wants of the town ; and if by any unforeseen contingency this 
stratum should fail to yield a sufficient water supply, there lies 
below it the Lower Green Sand, which has a more extensive 
outcrop still. The conditions of elevation were considered 
equally satisfactory. The mean level of the outcrop of the 
Upper Green Sand is about 300 feet above that of the mouth 
of the well, so that if no natural vent for the water in it 
existed at a lower level than the well, it must rise in it to the 
surface. These facts having been determined upon reliable 
geologic data, and there being no positive evidence of any 
break in the strata by w'hich the waters of the Upper Green 
Sand could pass into lower strata, operations w^ere commenced, 
and carried on until a d.epth of 1,313 feet was reached, and an 
outlay, as has been stated before, of upwards of £19,000 ex- 
pended. But, to the surprise of every one, not even the 
JJiyper Green Sand had been arrived at ; the bore, after 
traversing 848 feet of the chalk, was still in that formation, 
and from a comparison of data it was probable that from 20 
to 50 feet more of the chalk would have to be perforated before 
the Upper Green Sand was tapped. Then the question began 
to be discussed, supposing that the Upper Green Sand were 
reached, was it certain that it would contain a sufficient supply 
of water, or any water at all? In the attempt to bore an 
Artesian well at Calais both the Upper and Lower Green Sand 
were passed through without any water being found. In that 
of St. Grenelle, at Paris, the supply came from the Lower 
Green Sand only. It was known that there was a fault or 
irregularity in the chalk in the neighbourhood of Winchester, 
and it was just possible that this might so far have disturbed 
the Upper Green Sand as to allow its v/aters to pass into the 
strata below. Should this be the case the boring would have 
to be carried probably 250 feet lower down, at an additional 
cost of £3,000. Nor did it follow that when the Lower Green 
Sand was reached and found to contain w^ater that the water 
would rise to any height in the boring, for it might have a 
natural vent at a level lower than the month of the well, such, 
for instance, as would be provided by the termination of that 
