Imperial Valley press., 1909-05-15
EVAPORATION TESTS
Observations at salton Sea to Deter. mine Formula of Value to lrrias.
 ton Engineers.

Problems of evaporation, the solu- ton of which is expected to be Of great value in irrigation projects, ar being studied by the United States Weather Bureau at Salton Sea. The station at which the observations will be taken is located on the Southern Pacific near Salt Creek bridge, about one mile from Durmid and three and one-half miles from Salton.
 A preliminary examination was made in 1907 of the SaltCsf Sea and it's neighborhood, with q view to it's availability for extensive research in- to the laws controlling the rate of evaporation of water in the open air over large lakes and reservoirs. The tests showed that it is a splendid field for that purpose.
 The sea is nearly fifty miles in length and eighteen wide. Although the Alamo and New rivers are still discharging into it, there has been a subsistence of the water amounting to about seven feet.
 This great basin can never be drain ed because it is below the level of the sea. How long it will take the water to dry up under the slow pro- cess of evaporation is a problem diff1- cult of computation. Soundings re- gently made show that the sea in places is seventy eight feet deep.
 Four towers, for the purpose of ob- servation, have been erected. These are of open frame work, about 40 feet high. One is located on land, about 1500 feet from the sea; another stands in twenty-five feet of water, about 450 feet west of the railroad bridge; the third is about one-half mile from the bridge, in forty feet of water, and the fourth, a mile and q half from the shore, in 55 feet of water A gasoline launch has been provided to carry the observers and supplies to and from the towers.
 There are platforms every ten feet on the towers, and on each platform is a galvanized iron pan, two feet in diameter, and filled with water. Ob- servations will be taken every four hours. The data will show the amount of water lost by evaporation, it's tenn perature; that of the air at the sur face of the pan and of the air above the pan. Computations will also be
 made as to humidity and the yapor tension.
 As the velocity of the wind is an important factor, anenlometers will be placed at the top of the towers and near the surface of the water. More scientific experiments will be made as the work progresses and self-record- ing apparatus will be installed.
 In addition to the work at the main station observations will be taken at Mecca, on the upper shore of the sea; at Brawley, in the Imperial Valley, and at Mammoth, ill the desert.
 The object of this extensive re- -earch is to determine a formula for evaporation that will be of practical value to engineers. In irrigation pro-
 ects it is important to know just what volume of water will be lost by eyap- oration under normal conditions in or 1 der to build reservoirs large enough to meet all emergencies. The determin- ation of this formula has proven much more difficult task than was an Jicipated. The working out of prac- tical evaporation formula is in the hands of Prof. Frank Bigelow. Experiments to date have shown that the vital terms in a practical for mula are the temperature of the wa ter surface, the temperature of the air, taken by both wet and dry bulb thermometers, and the velocity of the wind. Besides these are, according to Prof. Bigelow, some unknown terms which may involve certain difficult phy- sical processes, like diffusion and | mixture of gases. It is the search for these unknown terms that is now being prosecuted.