1803.] On Draining and Watering. 249

are liable to shew a condensation of aerial yapour sooner than other places on the same level.-

As mountains are colder in proportion to their height, the evening mist sometimes commences sooner on them than in the valleys; but is seen earlier in these situations over the moister places, if they are on the same level with the drier ones, exactly as on the plains or valleys; and may therefore indicate the existence of springs, unless these moister places consist of hollow basons containing water, which if not at- tended to, may in all situations deceive the observer.

“Another observation for detecting springs may be made in rimy mornings; for as moist earth is a better conductor of heat than dry earth, the rime will sooner melt on those parts of the soil, which are kept moist by springs under it, than on other parts; as the common heat of the eaith, which is 48 in this country, will sooner be conducted upwards in moist places to dissolve the rime on the surface. On this account the rime is frequently seen on frosty mornings, when the heat of the air is not much above 32, to lie an hour longer on dry cakes of cow- dung, oron bridges, or planks of wocd, than on the common moist ground; as the latter much better conducts the common heat of the earth to the incumbent rime, which is in contact with it.

But as the heat of the common springs in this country is 48, where they exist, the rime is sooner dissolved than on the stagnant moisture of bogs or morasses. And as the springs about Buxton and Matlock, and at Bath and Bristol, are so wwuch warmer than common springs; it is highly probable, that where these waters approach the surface of the soil, they must much sooner dissolve the rime on frosty mornings; which may probably be observed in situations much higher than their present apparent sources; as they slide down_be- tween the interior strata of those hills, beneath the summit of which they are condensed from the steam of water boiling at great depths in the earth; which rises up through those per- pendicular clefts of the rocks, which were formed at their ori- ginal elevation.’ veh

In the winter months the rise of springs may be detected in moist ditches by the presence of aquatic plants, as of water- cress, water-parsnip, brook-lime; as in those ditches, which become.dry in the summer, these plants do not exist; and when those ditches with springs in them are nearly dry, it may be discovered which way the current has formerly descended by the direction of the points of the leaves of the aquatic plants as certainly as by a level; an_observation which[ jearnt from Mr. Brindley, the great canal-conductor of Stat- tordshire.:

Ag, Mag. Vol. 8. Mm