192 On the Causes u'hkh have operated 



chain of alluvi;i which, 7na?/^re Mr. Farcy's denial, does now 

 actually accompany the course of every stream from its 

 source to its termination, and which constantlv coi scspondj 

 with the strata traversed by the streams; — the innumerable 

 intcrseciioiis of valleys at the confluence of streams, iu 

 angles gcnerned strictly by the general fail of the country, 

 and the uniform levels on which these frequeiU ir.tersections 

 of valleys and streams meet; — eviucing with all the preci- 

 sion of mathematical demonstration, that such a niulti- 

 tudiuous unison of ei^ccts over the whole surface of the 

 globe cannot possibly be referred to any other natural cau.se 

 than the simple, obvious, and necessary operation of the 

 streams themselves. 



'i'hese were live clear, precise, and definite data on which 

 I resud the proof of the streaitis having every where exca- 

 vated their own vallevs. The references and the reasoning- 

 were necessarily general, because the question itself is one 

 of the most general that can be acitated, including the ex- 

 cavated vales in the course of every stream throughout every 

 country; and vet this widely extended case, Mr. Farey 

 would have to lie determined bv the datum of a solitary 

 valley, or a local spot : and by frittering the natural magni- 

 tude of the question down to the suborduiate and puny 

 case of what has become of the excavated materials. Now 

 admitting, in its fullest exten!, all that Mr. Farey has ad- 

 vanced on this laiter head, what would the whole infer, 

 but either that the vallevs have never been excavated at all, 

 or that the materials carried off have been removed to situa- 

 tions and distances where we can no longer trace them ? So 

 stronnlv iiicon j.ruous and unphilosophical are many of his 

 notions of valleys, that, probably enough, he mavdeiiy the 

 excavations altogether, althouiih there does not exist a 

 quarry or gravel pit in the kingdom, that bears more un- 

 equivocal indications of excavation than do our numerous 

 ranges of valleys. But, on the other hand, if Mr. Farey 

 admits of the excavation of valleys, in that admission 

 he fully accedes to tlie removal of the missing materials : 

 and by what practical or <-vcn possible direction will he 

 contrive to carry them off, other than downv^ards in 

 tbe same direction with the streams, where, however, he 

 so obdurately denies thev have ever travelled ? His avowal 

 that he is proud to repeal his beliefin the probability, that 

 valleys have been purposely and specially formed for the 

 streams wliich now flow through them, and that it is en- 

 gaging much of his attention, really surprises me. That 

 the (ihamiel of a canaJ has been purposely and specially 



formed 



