574 Correspondence — Mr. H. M. Soworth. 



under ; but it will have done its work. All I claim to have done is 

 to have framed an hypothesis which will meet all the facts known 

 to me. I have not shirked or wilfully evaded any, and I hope I 

 have accumulated a very considerable number as the basis of every 

 step in the argument. Further, the position I am fighting for is 

 only partially mine. I have merely tried to extend to all the beds 

 which are confessedly on the same horizon, however different in 

 texture, an explanatory cause which such great authorities as Mur- 

 chison, Belgrand, and Prestwich, have agreed in assigning to par- 

 ticular cases, and to show that the evidence is convergent and cumu- 

 lative. If I have misstated or misread facts, there is nothing will 

 be more grateful to me than to have my slips pointed out ; and if the 

 position is shown to be untenable, it will be surrendered at once, for 

 there is not time in seventy years, which is our portion here, to 

 fight for prestige. Of course when v^e take a new departure we 

 must adopt the jDositiou of Ishmael. We are bound to struggle with 

 those who already monopolize the ground, and I know of few better 

 examples to point the moral than Mr. Tylor himself He has defended 

 his Pluvial period with ingenuity and skill. He has written about 

 it in a way which has been a delight to myself to read, and although 

 he has not convinced many people that he is right, he has not done 

 the cause of science any the less good service by presenting certain 

 neglected aspects of a difficult problem in a striking light. Mr. Tyler's 

 second and third paragraphs I do not quite understand the apposite- 

 ness of. In answer to his arguments that the denuding influence of 

 a river upon its channel increases many fold with the increase of its 

 water, I urged that this does not follow, because the motion of a 

 river, especially of a deep full river, is largely limited to the upper 

 and central portions of its current, that it decreases as we get nearer 

 the bottom, while that portion in contact with its channel is nearly 

 quiescent. Do I understand Mr. Tylor to dispute this elementary 

 hydrostatical position, which is not a theoretical one, but has been 

 amply proved experimentally by a succession of observers, and 

 especially by Defontaine and Eaucourt? If not, I do not understand 

 the drift of his remarks. I may add hy the way that I have found 

 since I published the suggestion that the quiescence of the funda- 

 mental layers of water in a river may account for northern rivers so 

 frequently first freezing at the bottom, that the same suggestion had 

 been previously made, unknown to me, by Arago, and I willingly 

 shelter behind his aegis. 



Mr. Tylor's claim to have suggested as early as 1853 that the 

 crumpled gravels in the valleys of some of the French rivers were 

 produced by the mouths of these valleys having been gorged with 

 ice, is quite just; but in quoting Mr, Belt I was looking not at this 

 local fact, but at the important theory he formulated which proposed 

 to explain the valley terraces, etc., as lacustrine deposits, the Euro- 

 pean lake being embanked and pounded back by ice. 



Derby House, Eccles, Manchester, Henet H. Howorth. 



October, 1882. 



