[78] Hall (The Soil, p. 66) gives for the minima in the case of soils examined by him the following figures: coarse sandy soil, 22.2, light loam, 35.4, stiff clay, 45.6, sandy peat, 52.8. These figures are very much higher than for apparently similar materials used by the writer, and the differences exceed those between the maxima given for the same. This discrepancy I am unable to account for.
[79] Physics of Agriculture, p. 135.
[80] Rept. Cal. Expt. Sta. 1897-08, pp. 65-96.
[81] The quiet seepage from the banks and beds of streams plays a much more important part in the increase of volume of flow than is commonly supposed, because unperceived save by measurement of the tributaries and comparison with the main streams. This is especially true of the drainage in the arid region, where the deep and pervious soils favor diffuse seepage as against definite spring flow.
[82] Toumey (Yearbook U. S. Dep’t Agr. 1903) states that in the San Bernardino mountains in southern California, the first rainfall (in December) was absorbed to the extent of 95% in forested areas, against only 60% in the non-forested; but that later, after the soil had been partially saturated, 60% only was absorbed in the forested land, against 5% in the non-forested. While it is generally admitted that forests diminish the runoff, Rafter (Relation of Rainfall to Runoff, U. S. Geol. Survey Paper, No. 80, p. 53) contends that in New York State the reverse is true.
[83] Open Range and Irrigation Farming. R. H Forbes, in Forester, Nos. 7, 9, 1902.
[84] This effect is well illustrated by the behavior of a dry brick laid upon a wet sponge. It will quickly absorb all the liquid moisture contained in the latter, while the sponge will be wholly unable to take any moisture from a fully-soaked brick.
[85] Rep’t Calif. Exp’t Station for 1898 to 1901, p. 165.
[86] The exact record of these observations was unfortunately destroyed by fire; the soil was a heavy clay, and it took ten days before the water disappeared from the lowest hole.
[87] In contradistinction to other levels or “streams” of water which may usually be found lower down, separated from the first water by some impervious stratum of clay, hardpan or rock, and very commonly under sufficient pressure to rise somewhat higher than the point at which it was struck, owing to connection with higher-lying sources of supply. When such pressure is sufficient to cause an overflow at the surface of the ground, we have “Artesian” water as commonly understood.