(2) Transpiration also disposes of an ap preciable amount of rainfall in some localities through grasses, grains, other vegetation, shrub bery and trees and by them returned to the at mosphere. Bulletin No. 285 of the Bureau of Plant Industry of the United States De partment of Agriculture shows the water re quirements of various cereals and plants. Prof. Adolph T. Meyer states that 'For grasses and grains the ratio of pounds of water used to pounds of dry substance pro duced varies from 300.1 to 600.1.' B. E. Livingst.n has undertaken to show (40 Botanical Gazette 31) that there is a direct re lationship between transpiration and the weight of vegetables produced. The Depart ment of Agriculture of the United States has also undertaken to show that the yield of grain of an area is approximately proportionate to the water consumed. It will thus be seen that large quantities of water are taken up by the growing vegetation and forests of the earth and returned to the atmosphere. Growing crops absorb from 9 to 10 inches of rainfall and brush and trees from 4 to 12 inches of rain fall according to estimates made by Professor Meyer. Nearly all such water escapes from the stomata of leaves into the air, for the amount retained is very slight. Raphael Zon of the United States Forestry Bureau re ported in 1913, that one acre of oak forest in Austria absorbed upwards of 2,227 gallons of water daily, which was equivalent to a rainfall of l2)4 inches in a period of five months. These figures indicate the enormous quantities of water given off by forests into the air.
The United States Department of Agricul ture collected data in Central Europe showing the transpiration from forests to equal one fourth the rainfall there. Froth deductions of M. W. Harrington it appears that much of the rainfall is transpired Into the atmosphere by green crops and three-fourths of it from some forests and less than one-third from bare soil. During the growing season plants and trees draw moisture and water from the subsoils and thence it escapes into the atmosphere. The amount of water so taken from the ground by the capillary attraction in vegetation, plants and trees and by them transpired into the at mosphere varies greatly under different phys ical conditions, but enough has been stated to indicate that an appreciable part of the pre cipitation is thus disposed of and under some conditions that amounts to 20 (3) The runoff from different watersheds also varies greatly, depending upon their physical characteristics, including their geologi cal structures and configuration. Sandy faces freely absorb water and from them there is -le runoff. whereas clay and rocky soils ab 5 hut little rainfall and from such stir i• the runoff is large. Steep slopes also th. hater freely, wherejts forest-clad areas ref •1, absorb and retain a large part of the rai II. The following data will illustrate the an It .4 water disposed of in the localities tae 'ned by runoff. The runoff waters from of -Went areas or watersheds accumulate in pn •', Ponds, lakes and rivers and become one of two available sources of water supply, the tiler being ground-waters. From the Ge Lee River at Mount Morris, N. Y., ire 1.992 to the runoff ranged from 6.67 to .38 inches. averaging about 12 inches.
Prof. Adolph F. Meyer in his work on 'cements of Hydrology says that evapora tion and transpiration dispose of 15 to 25 Inches of rainfall and the remainder represents rur-ff which in. hides seepage and percolation.
Th !atter will be considered under the next set le. From the map of the Geological Sul ry prepared by Henry Gannett, it appears tha • he surface runoff over different water sbe ranges from three inches in the States CAS !. the Rocky Mountains to 60 or 80 inches in northern I'acific States. In the Central an •astern States, it approximates 20 inches.
Eai watershed, however, must be independ ent studied to determine its runoff. This vat ,, greatly in the different months and nee ,sanly averages much less than the rain fall Where the mean precipitation over the Mississippi reservoirs was 24.62 inches, the mc.m runoff was only 3.61 inches and the per .tilon averaged 14.7 inches. Over rite watershed it averaged 5.31 inches, or .early 25 per cent of the rainfall. The rat f runoff to rainfall ranged from IS pert arn - the Missouri basin to 24 per cent in the Oh In Ohio it amounted to 22 inches, At paint Croix, Wis., it was 9.6 inches, at Roo .ke. Va., it was 11.7 inches. In the Yazoo am -mit Francis basins, the runoff was 90 per eta f the rainfall. Over the Connecticut 161 where the precipitation for nine years aye 36 inches, the runoff averaged 21.9 inc From the James River watershed for tlry years, it averaged IA inches. At Ta kon Creek for 24 years, it averaged 26.10 tad .-% At Tombigbee, Miss., it averaged 17.10 inci at Sacramento, Cal., it averaged 20.4 Inc Over the Sudbury River, where the Pre station for 2a years averaged 45.4 inches, the was 21.5 inches. In the State of Neil York it averaged about 45 per cent of the John C. Hoyt and Robert Anderson in their 'Hydrography of the Susquehanna River Drainage Basin,' reported that the runoff in that part of the basin above Harrisburg from 110)1 to 1904, averaged from 49 to 55 per cent of the rainfall and at other places in the basin from 49 to 63 per cent of the rainfall. Over the Nashua River where the precipitation lot 13 years averaged 47.3 inches, the runoff averaged 219 inches. The runoff averages nearly SO per cent of the rainfall in New England. Over the Croton River, where the precipitation for 43 years averaged 4R.9 inches, the runoff averaged 23.3 inches. Over the Mil lain-Massapequa watershed, Long Island, N. Y , wiser, the mean precipitation was 4641 inches the runoff was about 30 per cent thereof. Over the Susquehanna River, where the pre cipitation for 10 years averaged 38.4 inches, the runoff averaged 21.3 inches. Over the James River in Virginia, where the precipita tion for 14 years averaged 42.3 Inches, the run off averaged 17.9 inches. Over the Potomac River, where the precipitation for 14 years averaged 37.4 inches, the runoff averaged 14.4 inches. Over the Muskingum, where for seven years precipitation averaged 4121 inches, the R runoff averaged 1420 inches. Over the ock River, Illinois, where the precipitation for five years averaged 33.88 inches, the runoff averaged 10.03 inches. George W. Rafter in 'Water Supply and Irrigation Pa No. 80 United States Geological Survey' pers gives the runoff for various years over 12 watershed., and it averaged from one-third to one-half the rainfall.