Having briefly examined the sedimentary character of the Mississippi, some investigations as to the proportion of sediment to water may be of interest. And it is well to state here that a mean stage of flow is taken as the basis upon which to start the experiments. The experiments and analysis of the water were made by Professor Riddell, at intervals of three days, from May 21st to August 13, 1846, and reported to the Association of American Geologists and Naturalists. The water was taken in a pail from the river in front of the city of New Orleans, where the current is rather swift. That portion of the river contains a fair average of sedimentary matter, and it is sufficiently distant from the _embouchure_ of the last principal tributary to allow its water to mix well with that of the Mississippi. 'The temperature,' says the Professor, 'was observed at the time, and the height of the river determined. Some minutes after, the pail of water was agitated, and two samples of one pint each measured out. The measure graduated by weighing at 60 degrees Fahrenheit 7,295.581 grains of distilled water. After standing a day or two, the matter mechanically suspended would subside to the bottom. Nearly two thirds of the clear supernatant liquid was next decanted, while the remaining water, along with the sediment, was in each instance poured upon a double filter, the two parts of which had previously been agitated, to be of equal weight. The filters were numbered and laid aside, and ultimately dried in the sunshine, under like circumstances, in two parcels, one embracing the experiments from May 22 to July 15, the other from July 17 to August 13. The difference in weight between the two parts of each double filter was then carefully ascertained, and as to the inner filter alone the sediment was attached, its excess of weight indicated the amount of sediment.' As the table may be interesting, showing the height and temperature of the water as well as the result of the experiments at the different times, we introduce it complete: TABLE _showing the Quantity of Sediment contained in the Water of the Mississippi River_. Date of Height Temperature. Grains of Sediment Experiment. of River in a Pint of above Water. Low Water.