348 On Draining and Watering.[April,

inch and a half in diameter, and was bored about fifteen yards deep through the uppermost stratum of marl into the sand be- neath it, and supplies Dr. Darwin’s house with two or three hogsheads of water aday. And Mr. Strutt, near St. Peter’s Bridge, has sunk a well for the use of his steam-engine about 200 yards from the former, which passes through the same upper stratum of marl, and is three feet in diameter at the bot- tom, and supplies, when required, a hundred hogsheads in a ay.

‘The knowledge of this part of geology leads to another use- ful purpose, the discovery of springs, concerning which some have pretended to possess secret or my stical intelligence, both in England andin France. When the eminences of a coun- try were raised out of the primeval ocean by subterraneous fires, some of them were raised nearly equally on all sides, like the limestone mountain at Breedon in Leicestershire; in which the central stratum may be seen to stand nearly erect or verti- cal, and those on all sides at considerable inclination. Other mountains were abruptly broken off on one side only from the adjoining earth, like those which form the high torr at Mat- lock; which rise with one of their sides perpendicular asa wall by the Derwent side; so that the strata of the former of these mountains may be represented, as before mentioned, by the bur, which would be made on some folds of paper, if a very hard blunt instrument was thrust through them; and the latter by raising up one edge of such folds of paper, so as to incline the whole of it at some angle with the horizon.

As the springs consist of the water, which slides between these inclined strata; itis evident, that in some eminences of ground they are only to be met with on one side of the moun- tain; and in other eminences of ground on all sides of it. In searching for springs therefore attention should be given to the inclination of the strata of that part of the country, which may be often seen in marl-pits, gravel pits, or im hollow lanes. But they may in general be found above any moist or morassy plain or valley; the moisture of which shews, that springs ex- ist in the strata on that side of the mountain.

A second observation for the purpose of detecting springs may be made on misty evenings; as those parts of the ground where the mist commiences, are moister than those in their vicinity on the same level; and in consequence may generally, if they are not hollow basons, possess springs nearer the sur- face; for these moister parts of the ground, having evaporated more during the day, are become colder on their surfaces than the drier ground in their vicinity; and in misty evenings, which are at the same time calm, the stationary air over these moist parts of the ground is also more loaded with‘the evaporated moisture; and on both these accounts these moister situations