TREATISE BT HEEK WEX. 189 



that since the dearing away of many forests, more especially in the 

 mountains, deluges of rain and rain-spouts occur more firequentiy ; 

 further, while the rain-water, in lands devoid of trees, sinks less into 

 the son, it at the same time more speedily reaches the brooks 

 and streams and rivers, and fills and overflows these water-courses ; 

 and finally, the body of water, now tearing along with rapidity, cuts 

 up the mountain sides cleared of forests, and fills up the beds of the 

 brooks and streams and rivers with earth and sand and rubbish, and 

 so raises the bed of the liver — whence a higher level is reached by the 

 water-surface. 



" The correctness of this aU^ation is being attested, in a way 

 which it is saddening to contemplate, by the ever more frequently 

 recurring inundations in Italy, in the south of France, in Hungary, 

 in Bohemia, and in many other lands. 



" The aforementioned phenomena of high floods led a distingnished 

 meteorologist to express to me the conjecture that the great increase 

 of the body of water passing along our water-courses, in high floods, 

 may be about equal to the diminution observable in the low and 

 mean levels. 



" This conjecture, however, is not in accordance with the fects of 

 the case, because, as I have already shown, in the case of the Bhine 

 and of the Elbe, the annual delivery is approximately represented by 

 the mean water-levels, which, even in aU these five rivers named, is 

 on the decrease. But the incorrectness of the conjecture is more 

 particularly manifested by the tabulated observations by the p^el at 

 Orsova, in as much as, from the geographical position of the very 

 extensive basin drained by the Danube, it frequently happens that 

 the high floods of several of the laige affluents coincide in time with 

 that of low water level in several other important accessories of the 

 river, and yet there is not an equivalent compensation for the lesser 

 supply coming from the one class of affluents, in the greater supply 

 coming from the other, in as much as, even at Orsova, the average 

 of the floods of the mean and of the lowest levels have fallen stiU 

 more than have these in the four other rivei3 named. 



"But even i^ iu accordance with this conjecture, in particular years 

 with repeated extraordinary high floods, some such eqxiaUsation of 

 the increased and the diminished delivery of a river should occur, 

 this would supply but little consolation for man, as the great evils 

 consequent on the diminution of the delivery of water at the lowest 

 and the Tnean levels are not obviated by the more frequent occurrence 

 of the greater delivery during high floods, but are being more than 



