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JOURNAL OF THE PLYMOUTH INSTITUTION. 
plentiful supply at one side or other, or both, as circumstances 
determine. 
A large cutting in Mount Gould through the blue and white 
rocks has also shown the very prescribed limits enjoyed by under- 
ground water. Only three or four springs have been met with, so 
sound is the rock, with very little spar and few changes. Some- 
times a bed or mass of broken rock is come upon, the rock not 
having been removed from its original position, but fractured in 
situ ; such broken rock always carries water. 
One other instance to show how clearly defined the water chan- 
nels are. During the construction of the Devonport Railway at 
Stoke, an excellent well was destroyed, and had to be replaced, 
a new one having to be substituted. A first attempt failed ; on 
observing, however, a "weeping" in the face of the cutting, 
another well was put down six yards from the first, and success- 
fully. 
On the whole, the well-sinker's dictum, " water can only be 
looked for at a change of ground," is correct ; and as spar is 
generally associated with an extensive change of ground or dis- 
turbance we can understand their prediction, that when spar is 
struck there is every chance of a plentiful supply of water. Many 
wells bear out the perfect truth of these statements. A well near 
the top of Stoke Hill was sunk for the first 1 0 feet through a firm 
clay, then through shillat, and was perfectly dry, till at a depth 
of 15 feet from the surface a bed of spar was struck, from which 
a plentiful supply was obtained without sinking farther. 
Stoke generally has abundance of water underground, from wells 
sunk on an average 25 feet deep. The bands are not very broad ; 
here and there is a frequent occurrence of fissures containing spar. 
Similarly, at Torpoint, there are many excellent wells, due to the 
same formation. Returning to Plymouth, we find the same to hold, 
more or less, for all the district near the North Road, and eastwards 
to the summit of the hill on which stands the Prison. 
A well at Endsleigh Place, in the yard of Mr. T. Jinkin, con- 
tractor, may be taken as a fair specimen of the better class of com- 
mon wells in this district, and indeed in the shillat generally. Here 
the ground rises towards the north, falls rapidly to the south, is 
level on the east, and falls on the west. There is an abundance of 
water, but this abundance was secured by driving a heading north 
against the dip for 12 feet, at a depth of 24 feet from the surface. 
