59 
(drawing No. 2) from which it will be seen that the stream 
traverses for a distance of about four miles the Inferior Oolite, 
and for about one mile the Great Oolite. In both of these, 
especially in the loose rocks of the Inferior Oolite, there is 
considerable loss of water from the stream hereinafter more 
particularly described. 4 
Taking the basin of the river) at 55 sq. miles, and the 
standard flow of 12 cu. feet per sq. mile, we should obtain a 
daily flow of the Churn, at the junction with the Thames, 
near Cricklade, of 5,940,000 gallons, taking 7 cu. feet per 
sq. mile, the ascertained minimum flow of the Thames at 
Lechlade, we should obtain 3,465,000 gallons per diem ; but it 
does not, I think, attain this volume even, or probably much over 
‘two millions of gallons per diem in a very dry season. I have 
carefully gauged the Boxwell springs at such times where the 
waters lost from the river in the upper levels, or some of them, 
again re-appear and re-establish something of a river, and 
found them yielding at one time, on August 5th and 6th, 1864, 
an average of 1,108,800 gallons per diem, and on Oct. 10th of 
the same year 1,121,758 gallons per diem. These springs are 
of a very interesting character; they boil up ata number of 
places in a withy bed, and uniting, form a strong tributary, 
quickly joining the Churn, three miles from its junction with 
the Thames. Their artesian rise is on a line of fault, shown 
on the Ordnance Geological Map, running a little north of 
South Cerney, nearly east and west, apparently from a con- 
siderable depth. 
The waters lost from the Churn, in traversing the Inferior 
Oolite between Colesbourne and North Cerney, a distance of 
four miles, as ascertained by gaugings made by the late Mr 
Suueson, President Inst. C.E., and myself, in October, 1859, 
amounted to 267 cu. feet per minute, equal to 2,403,000 gallons 
per diem. Such waters, as they pursue a subterranean course 
down the valley, are imprisoned between the clays of the 
Fuller’s Earth and the Upper Lias beds. Again, in traversing 
the Great Oolite, near Baunton, water is also lost, from the 
stream similarly becoming subterranean and imprisoned between 
