National Geographic : 1897 Dec
THE DELIA OF THE MISSISSIPPI RIVER to experts in other lines, for the work in hand pertains mainly to ascertaining the quantity of supply, its variations, and its use. The facts which have been put on record are those concerning the source and quantity of water in the river, the location and character of the polluting agencies, and inferentially the degree to which the sewage or waste is diluted by the annual flow of the stream. Until state or national legislation can be secured to regulate such matters, the Potomac, as in the case of all interstate streams, must serve as a sort of sewer into which town and manufactur ing establishments empty their refuse, and this fact must be borne in mind in all considerations of water supply. The im provement of water supplies from this source should begin at both ends-that is to say, pollution should be prevented as far as possible and the water supply for a city should be filtered. The state of Massachusetts has set the example in this respect, preventing the pollution of streams by gradually forcing towns to provide suitable sand filters for sewage before allowing it to discharge into certain rivers, and also by providing similar sand filtration for the water which is to be used for municipal pur poses. The system of intermittent sand filtration has been found to be efficacious not only in taking out visible particles but in nitrifying and destroying the smaller organisms apparently so potent in matters of public health. THE DELTA OF THE MISSISSIPPI RIVER* By E. L. CORTHELL, C.E., D.Sc., etc. The Mississippi delta proper extends over 100 miles by the course of the river above the city of New Orleans. The materials composing this great mass of sedimentary deposit have been partly disclosed by numerous artesian wells which have from time to time been driven for the purpose of obtaining, if possi ble, potable water. The most notable instance, and where prob ably the most careful observations were made, is the artesian well at Lafayette square, New Orleans. At a depth of 1,042 feet the tool was broken and the work ended, but driftwood was pumped up at the last foot. *Abridgment of paper read before the Geographical Section of the British Associa tion for the Advancement of Science, Toronto, August 24, 1897.