62 
before the Geological Society on March 10th, 1886, that the 
saline waters may have escaped from a ridge of Paleozoic 
rocks, against which the Lower Oolitic rocks abutted, as they 
do on the Mendip hills. In this view it would probably have 
been better had the sinking been located two or three miles 
further north, some way beyond the fault between Purton and 
Rodbourn Cheney, shown on the Ordnance Geological Survey 
Maps; but of course the presence of such a brine spring as 
that tapped in the Forest Marble could not have been antici- 
pated, and it may be “‘tubbed out” should good water from 
the sands before referred to be reached below. 
I approach now a subject of interest, particularly to our 
Stroud friends, the river Frome, of which river I have taken 
periodic gaugings during many years, at various points. I have 
plotted some of them on the Hydrological Charts, now on the 
table, (see Drawings Nos. 3 and 3a) which show the flow of that 
river at Iles Mills, Chalford, and at Brimscombe Port, during 
periods of 1878, 1879, 1880, 1881, and 1882. It is remarkable 
that whilst the apparent drainage area to Chalford is but 23 
sq. miles, which, according to the Thames standard, would 
produce 276 cu. feet per minute, we have a minimum flow there, 
and that only for a short period, during 1881, nearly three times 
that quantity,* an ordinary flow exceeding 1000 cu. feet per 
minute, and a maximum flow of about 8000 cu. ft. per minute. 
From this it would appear that the variation in the discharge 
of these springs is between 1 and 10 approximatively. 
The large volume of water issuing from the Chalford springs 
clearly shows the subterranean character of the Frome in 
traversing the fissured and cavernous rocks of the Inferior 
Oolite from a point about a mile below Miserden to Chalford, a 
distance of six miles. The river at Edgeworth mill downwards 
to the bottom of the Golden Valley is practically dry during 
seasons of drought, then within a distance of three quarters of 
a mile it again breaks forth from a number of spring tributaries, 
* The flow of the river Churn at Colesbourne, due to 16 miles of 
drainage area, was found to be 312 cu. ft. per minute, being nearly 20 cu. ft. 
per minute per sq. mile, as before noted. ; 
