41 



" 1. As the aforesaid rivers are fed mainly by the brooks and streams which flow 

 into them, there must have been also in these a continued decrease in the quantity of 

 water delivered by them for a great many years, from which we may further conclude 

 that if observations had been' made on the levels of the different feeders, similar to those 

 which have been made on the five large rivers named, and these had been compared, they 

 would have supplied results similar to those at which we have arrived concerning these. 



" The correctness of this allegation receives confirmation from the fact that many 

 manufactories, etc., which have been built during the last fifty years, on rivulets and 

 streams, have experienced a marked diminution in the quantity of water coming through 

 their water-leadmgs, and it has been found necessary to employ steam-engines to meet 

 the deficiency of their water-power, which was originally sufficient for the work they had 

 to do. 



" 2. As it is possible that the causes which have produced the effect of the lowering 

 of the water level, and diminution of the quantity of water delivered in these five 

 river basins, operate equally in the basins of the other rivers and streams in Europe, and 

 not only so but in the most populous and cultivated districts of the other three quarters 

 of the globe — it may be assumed that in most of the streams and rivers on the surface of 

 the earth, a similar lowering in the lowest and mean levels of the body of water delivered 

 by them has taken place ; while the high floods in the same, reaching a higher point, and 

 becoming of more frequency, discharge a greater quantity of water, and produce more 

 extensive devastating inundations than previously was the case. 



" 3. If the causes which have operated in producing the decrease in the usual water 

 flow of the streams and rivers, with the rapid overflowing of them in times of flood, in 

 the course of the last 140 years, were to continue to operate also in the future, it is 

 evident from what has taken place that in brooks, and streams, and rivers, the lowest 

 and the mean level of these may be expected to be lowered still further in the future. 

 And the question forces itself upon every one involuntarily to what degree may this 

 diminution in the quantity of water thus delivered by the several streams and rivers be 

 carried 1 , 



" A consideration of the three rivers — Weser, Elbe, and Oder — makes clearly mani- 

 fest a reduction in the quantity of water delivered by them, and a silting up of the river- 

 bed with sand. It has been calculated that if the Elbe continue to diminish in the future 

 at the same rate at which it has been diminishing up to this time, it will soon be impossibe 

 for heavily laden ships to pass by it. Nor is it otherwise with the Oder ; in the very 

 dry year 1858, there were only eleven days in which the navigation of the Oder in Silesia 

 could be carried on with full force. The Weser delivers the smallest body of water of the 

 three. One principal reason for this is the destruction of forests which has taken place 

 on the heights which are found alongside of the river, and which the Government have 

 latterly taken steps to prevent ; but still more than what has resulted from the destruc- 

 tion of forests has been the consequence of the rectifications of the river-bed, which it has 

 become a general practice to carry out. 



" After weighing fully the collected observations on the water level, and consequences 

 deduced from them in the foregoing treatise, I think no Hydrotechnik will venture to 

 call in question the correctness of the allegations advanced by the distinguished hydro- 

 grapher Dr. Berghaus, in the year 1835, which allegations have been confirmed and 

 established by myself, that in the brooks, streams, and rivers in Central Europe, within 

 the period of observations, extending over about 140 years, high floods now appear and 

 attain a greater height ; on the contrary, the lowest, and the mean levels of the rivers are 

 falling, and consequently the delivery of the water by these streams and rivers is being 

 continuously diminished to a very great degree." 



There follows an expression of the views of the author on the great practical importance 

 of the fact brought to light. In the second chapter he describes the reduction observed 

 in the flow of springs and in the quantity of water yielded by them, and after citing 

 numerous facts, illustrative of these points, he thus concludes : — 



