FLOODS. The mean annual precipitation over the entire basin is estimated by Humphreys and Abbot at 29.8 inches. The estimated discharge of the river is 610,000 cubic feet of water per second. The precipitation, however, is subject to great variations at different seasons—which fact, together with the sudden melting of the stored-up snow in the spring, causes considerable variations in the volume of the various tribu taries. Fortunately, all are not at their highest at any one time; for if they were, probably noth ing artificial could resist the force of the accunm lated waters. The regions from which the floods come are so far apart and differ so widely in cli mate that, as a rule, one floofl passes before an other comes. As it is. the volume of the floods that come is sufficient to make a variation of over fifty feet between high and low water marks. The greatest difference recorded at Cairo is 53.2 feet, and at Vicksburg there has been known to be a difference of 55 feet. At flood times the water at Cairo is 320 feet above the mean tide water at the mouth of the river. At low water it is 274 feet above mean tide. This fall in a channel 1097 miles long fully accounts fur the great velocity of the current, which varies from three to six feet a second, according to existing conditions. In high floods the river formerly overflowed nearly all the surface between the mouth of the Ohio and the Saint Francis River in southeastern Missouri and eastern Arkansas, filling the lakes and lagoons of that region, and then flowing by numberless channels to the White River and Arkansas, the Bayou Macon, Washita, Red, and Atchafalaya rivers into the Gulf. Even since the levees have been built
(see below), the river sometimes breaks through these; its waters then flow down the slope of its ridge, and collect in the lowlands. forming lakes. These rise gradually, extending up the slope of the ridge, and so flooding the farms and planta tions. In the spring of 1807 a flood created many crevasses in the levees and swept over a great tract of territory, causing heavy losses in stock, crops, and other property. On March 14th the water reached the highest point ever recorded at Memphis, Tenn. On April 5th. according to an official statement of the Department of Agricul ture. the total area under water was 15,800 square miles, the submerged land being for the most part in Missouri, Mississippi, Tennessee, Arkansas, and Louisiana. Further damage was subsequently caused by breaks in the levee at Biggs and La Fourche Crossing, La., which resulted in the flooding of large tracts of land below Vicksburg, Miss. It was estimated toward the close of April that 20,000 square miles, containing 46,936 farms, according to the census of 1800, were under water. According to some estimates, from 50,000 to 60.000 persons suffered serious losses from the floods. The Citizens' Relief Committee of Memphis cared for large numbers of the refu gees. The destitution was so widespread, how ever, that President McKinley sent a special message to Congress, which appropriated $200,000 for the immediate relief of the sufferers.