STATKWKNI BY HERE WEX. 185 



considerable deepening of the bed of the stream, consequent upon 

 extensive rectifications of the river by cuttings. 



" Further, although it must not be concealed that the different 

 water-levels measured, and deliveries calculated, cannot be relied on 

 as absolutely correct, and it is unquestionably the case that the 

 deepening of the bed of the stream had a great effect upon the 

 lowering of the level and the reduction of the delivery, stiU it must 

 be noted that the fall and diminution in the one and the other, which 

 have been determined, have been brought to light by the same 

 method, and are in any case approximately correct ; from which it 

 follows as a consequence, that in the latter period (embracing 28 

 years), at the pegel at Germersheim, the body of water delivered by 

 the Rhine has considerably diminished. 



" Along with this mnst be noted the very remarkable &ct, that 

 the beautifully rectified course of the Rhine firom Manheim upwards 

 toward Basle, converting it almost into a regular canal, has now become 

 in a great measure unnavigable : in consequence — first, of the 

 numerous persistent and extending beds of silt in the bed of the 

 . river, and resting in the concave sweep ; and next, of the con- 

 tinuallyincreasing serpentine character of the course of the stream; and 

 finally, of the low depth of water in the many crossings of the stream 

 from one concave bay to another, aU which can now be accounted 

 for by the feet that the normal breadth of the river-bed was originally 

 taken to be greater than it actually is, from which it follows that the 

 current, in consequence of the diminished water-flow, has not now 

 the force necessary to remove these masses of silt, and to lodge 

 them only on the convex or projecting shores of the river-bed. 



" The forgoing results of observations made on four gauges on the 

 Rhine, serve to strengthen my allegations in regard to this river j 

 and I proceed to the consideration of the information obtained in 

 regard to the other rivers of Central Europe." 



There are given in an appendix the several tabulated observations 

 and diagrams referred to. There foUow discussions similar to those 

 which have been quoted in detail : 1. Of observations made on the 

 Elbe, with a tabulated statement of observations of the highest, Tnean, 

 and lowest levels of the river at Magdeburg, with the calculated means, 

 and a diagram representative of the same, from the year 1 728 to 1869, 

 a division of the former of these being made into periods of 50 years ; a 

 diagram representative of the calculated delivery of the Elbe in the 

 several months of the year during the two periods from 1 731 to 1780, 

 and from 1781 to 1830 ; and a diagram representative of the depth in 



T 



