250 The Edinburgh New Philosophical Journal. 



stream to its exit from the mountains, a distance of fifty 

 miles. The five great branches of the Brahmaputra emerge 

 from lateral fissures in the Himalaya into the valley of 

 Assam by as many gaps or Doars. We have never ap- 

 proached sufficiently close to any of them to become 

 acquainted with their local scenery, but this is probably 

 equal to the pass of the Gogra, if not still more magnifi- 

 cent. It does not appear from the papers of MM. De Luc 

 and Hoffmann that any attempt has been made to assign 

 a cause for this universal peculiarity, although we think 

 it may be accounted for by the following consideration. 



Mountain chains are usually extended along the centre 

 of continents, where they run more or less parallel with seas. 

 The waters which their lofty summits attract from the at- 

 mosphere would thus be conducted along their narrow 

 vallies, instead of falling from their sides to fertilize, as 

 they do, extensive portions of the earth, which would other- 

 wise be uninhabitable. We cannot be surprised therefore 

 that Addison, De Luc, and others, should have perceived 

 something like the hand of Providence in directing the course 

 of the Rhine through the chasms that appear to have open- 

 ed for its escape, and that the attention of philosophers 

 should be now awakened to equal indications of design in 

 the lateral defiles by which nearly all the great rivers of 

 the earth emerge from their mountain barriers. With the 

 exception of MM. De Luc and Hoffmann, we are not 

 aware of the subject having specially occupied the minds 

 of geologists, and they seem to have merely noticed 

 the effect, without regard to the causes to which it may be 

 ascribed. 



The power of water in overcoming resistance, is in pro- 

 portion to the velocity of its current, or the obliquity of its 

 fall; the fall must always be more rapid in a direct than 

 in a circuitous course, and hence there must be a tendency 

 in all rivers to effect the shortest passage to the sea. Where 

 mountain barriers are in question, no hydrostatic power 



