. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 1844.] THE CIVIL ENGINEER AN ARCHITECT'S JOURNAL. Ill 77-5 21 008 100- a trace wlietlipr it is not advisable to savf the drainage waters, and after evaporating, by some means, to restore tbem to the soil, as doubtless they must contain these salts, which would be so beneficial to the crops. The shrinkacc of soils in dry weather seems to be in proportion to the clay or'orRanic matter present. Clays and peats in drying shrink one-fifth of their bulk. This action is of grea
. The Civil engineer and architect's journal, scientific and railway gazette. Architecture; Civil engineering; Science. 1844.] THE CIVIL ENGINEER AN ARCHITECT'S JOURNAL. Ill 77-5 21 008 100- a trace wlietlipr it is not advisable to savf the drainage waters, and after evaporating, by some means, to restore tbem to the soil, as doubtless they must contain these salts, which would be so beneficial to the crops. The shrinkacc of soils in dry weather seems to be in proportion to the clay or'orRanic matter present. Clays and peats in drying shrink one-fifth of their bulk. This action is of great utility, by increasing capillary aclion, and by forming conduits, by which the supeiduous water may run off. Of course this does not take place in sandy soils. The absorption of heat by the soil during sunshine is very great, some- times raising its temperature 30° or 40° over that of the air. When the air has been at 70' or 80'. the soil has been observed, during sunshine, at 100' or 120°. Black lands will rise rather higher in temperature than those of a lighter colour, but not so much so as might have been imagined ; the greatest difference observed having been 10'. When a chalk was observed at 100', a neighbouring black loam was at 110°. The difference of absorption of heat by different colours may be illustrated by placing pieces of phosphorous on three pieces of tin, one with its own surface, one coloured white, and the other coloured black, and placing a hot iron ball between them at an distance, to represent the sun. The phosphorus will be ignited first on the black, next on the wdiite, and lastly on the metallic surface. Those soils which absorb the quickest, radiate the quickest, and consequently would be coldest at night. The subject next claiming attention is the atmosphere, and which here in- troduces an important division of the subject; for as the soil has Ijeen con- sidered as being the source of the inorganic part of plants, so the atmosphere is co
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