At Hamburg and Altona the water is generally tolerably clear, but at times of flood the Elbe becomes very turbid, and the amount of mud deposited in the sedimentation-basins is considerable. At Dresden, several hundred miles up the river, I have repeatedly seen the river-water extremely turbid with clayey matter, the color of the clay varying from day to day, corresponding to the color of the earth from which it had been washed. At Budapest, where filters were used temporarily, the Danube water was excessively muddy with clayey material. At first very high rates of filtration were employed and the results were not satisfactory. Afterward the rate of filtration was limited to 1.07 million gallons per acre daily, and good results were secured. There was no preliminary sedimentation. Professor Nichols reports the average suspended matters in the Danube at 32.68 parts in 100,000, but does not state at what place. Many of the French and German rivers drain prairie country not different in its general aspect from the Mississippi basin, and the soil is probably in many places similar. There is no reason to suppose that the turbidities of these streams in general are materially different from those of corresponding streams in the United States, although it is true that, other things being equal, the average turbidity of water taken for water-works purposes will increase with the size of the stream; and it may be that some American streams, especially the Ohio, Missouri, and Mississippi rivers, are of larger size than European streams, and consequently that the turbidity of the water taken from them for water-works purposes may be greater. The following are the drainage areas of a number of European and American streams yielding more or less muddy waters at points where they are used for public water-supplies after filtration, with a few other American points for comparison. The results are obtained in most cases from measurements of the best available maps.