THE ACTION OF FLOWING STREAMS. 739 



Kev. E. Hill was glad to hear a paper on physical geology. The 

 two parts of the paper appeared to be separate. The dependence 

 of the velocity of the stream upon the coarseness of its burden 

 appeared to be a paradox, and perhaps was put forward as such. 

 The alternation of " fan " and " canal," or, as Mr. Oldham called it, 

 " reach," is well illustrated in the Alps, and must be produced 

 whenever a succession of steps is traversed. 



Prof. Blake suggested that Mr. Oldham might mean that it 

 depended on the coarseness or fineness of the material introduced 

 into the stream, whether it was retarded or not in its lower reaches 

 and so made to alter its velocity. 



Dr. Blanfokd said that he understood Mr. Oldham to express 

 the view that the velocity of a stream was dependent upon the 

 coarseness or fineness of the solid materials transported, a view in 

 favour of which the speaker did not think Mr. Oldham had brought 

 forward valid evidence. The observations on the alternation of 

 " fans " and " reaches " were interesting, and alternations of a 

 similar nature, of faster and slower areas, occurred in all parts of 

 rivers. It was, however, unfortunate that Mr. Oldham's critical 

 illustrations were taken from localities where the course of the rivers 

 had been afiected by the Ganges canal-works. 



The President regretted that Mr. Oldham's paper was heard at 

 a disadvantage, as the Author was not present to reply to the 

 remarks made. 



