ABSTRACT
I made two sets of observations, the one in the month of August, and the other in November. The apparatus I used was very simple, but answered the purpose perfectly…. It consisted of a stone bottle, capable of containing about a gallon, furnished with a cork covered with leather, and greased; a weight of about 10 lb. was attached to the bottom of the bottle by a rope, of such a length, that, when the weight touched the ground, the mouth of the bottle might be at the desired distance from the bottom of the river. A rope was attached to the ear or handle of the bottle, by which it was let down, and a string was fastened to the cork. As soon as the bottle had reached its destined position, the cork was withdrawn by means of the string, the bottle became filled with the water at that particular depth, and was then instantly drawn up. The water, as soon as drawn up, was emptied into glass jars, on which I had previously marked a certain measure. The quantity of water on which I intended to operate, was a cubic foot, or 1000 ounces, and I collected it at different times; for instance, after one-third of a cubic foot had stood in the jars for some days, I drew off the clear water with a syphon, and another third of water, fresh taken from the river, was added to the sediment left at the bottom of the jars from the first; that was allowed to stand,
the clear water was again drawn off, and the last third was added in the same way. When this had stood a sufficient length of time, the accumulated sediment was removed to an evaporating dish (a common saucer will do quite well), and carefully dried in a gentle heat. The dried mass was the amount of solid matter held in suspension in a cubic foot of water, and now in the state of indurated mud. (Horner, 1834-5, p. 103)
(First observation-August, 165! from the left bank, 6! from the river bottom.) A cubic foot of distilled water weighs 437500 grains, therefore the solid matter
amounted to Part of the cubic foot of water. (Horner, 1834-5, p. 104) (Second observation-November, Middle of river, 1! below the surface.) The
residuum, when dried in the same manner, weighed 35 grains, which is Part of solid matter in one cubic foot of the water. (Horner, 1834-5, p. 104)
The above experiments shew, that the quantity of solid matter suspended in water, which, in the mass, has a turbid appearance, may be very trifling. But the extent of waste of the land, and of the solid materials carried to the sea, which even such minute qualities indicate, is far greater than we might be led to imagine possible from such fractions. It is only when we take into account the great volume constantly rolling along, and the prodigious multiplying power of time, that we are able to discover the magnitude of the operations of this silent but unceasing agency. In the absence of more accurate data for my calculations, for the sake of shewing how large an extent of waste is indicated by water holding no more solid matter in suspension than is sufficient to disturb its transparency, I shall assume that the Rhine at Bonn has a mean annual breadth of 1200 feet, a mean depth throughout the year of 15 feet, and that the mean velocity of all parts of the stream is two miles and a half per hour. These assumptions are probably not far distant from the truth. I shall take the average amount of solid matter in suspension to be 28 grains in every cubic foot of the water. (Horner, 1834-5, pp. 104-5)
We have 145,980 cubic feet of stone carried down by the Rhine past the imaginary line every twenty-four hours, …a mass greater in bulk than a solid tower of masonry sixty feet square, and forty feet in height. If we multiply 145,980 by 365, we have 1,973,433 cubic yards carried down in the year, and if this process has been going on at the same rate for the past two thousand years,—and there is no evidence that the river has undergone any material change during that period,—then the Rhine must in that time have carried down materials sufficient to form a stratum of stone of a yard thick, extending over an area more than thirty-six miles square. (Horner, 1834-5, p. 106)
Besides these lone precursors of the quantitative school many useful discoveries were made about the processes concerned in the shaping of river beds. J.Yates in an informative paper to the Geological Society distinguishes the various sources of the alluvial deposits and traces how they reach their present positions and assume their present shapes. Weathering he recognized to be an active agent of distintegration which supplied most of the material transported by the rivers. He also appreciated that the rivers in turn sorted this material out, carrying the finer particles in suspension; rounding and rolling the larger fragments along the bottom. Another aspect which he noted was the
effect of changes in the level of the river bed and to this cause he attributed the occurrence of alluvial cones and shallows wherever a tributary at a higher level joined the principal stream.
