suspended in the Water of the Rhine. 105 



into account the great volume of water constantly rolling along, 

 and the prodigious multiplying power of tivie, 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 sus- 

 pension than is sufficient to disturb its transparency, I shall as- 

 sume 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 dis- 

 tant 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. 



If we suppose a mass of water of a foot in thickness, 15 feet 

 in depth, and 1200 feet in length, we shall have a column across 

 the river containing 18,000 cubic feet; and 18,000 x 28 give 

 504,000 grains of solid matter in that column. 



A cubic foot of distilled water weighs 437,500 grains, and if 

 we take the solid matter as having a specific gravity of 2.50, a 

 cubic foot of it would weigh 1,093,750 grains. 



If the river run with a mean velocity of two miles and a half 

 in the hour, 13,200 such columns would pass a line stretched 

 across the river every hour, and 316,800 such columns every 

 twenty-four hours ; 



(1760 yards in a mile = 5280 feet, x 2^ = 13,200 

 and 13,200 x 24 = 316,800.) 



If 316,800 columns be multiplied by 504,000 grains, and the 

 product 159,667,200,000, be divided by 1,093,750, (the num- 

 ber of grains in a cubic foot of the solid matter), 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 last two 

 thousand years, — and there is no evidence that the river has un- 

 dergone any material change during that period, — then the 



