1S99] THE LIVES OF STREAMS 333 



River development is so complex a subject, requiring to be considered under 

 so many headings, and the various phenomena so interact among themselves 

 that the difficulty of a concise arrangement may be granted. Nevertheless 

 that is just why it is important. Such a work seems to require division into, 

 for instance, (1) river mechanics, (2) river growth, individually, (3) river life- 

 history, throughout a geographical cycle, and (4) growth and decline of 

 what may be called river groups. 



Now, while the author has admirably considered the first of these divisions, 

 he seems not to have made sufficiently clear distinctions in regard to the others. 

 To indicate what is implied it seems necessary to turn to biological language. 

 Thus our second suggested division may be called river ontogeny — the growth 

 from source to sea ; the third, river phylogeny — the phases of development 

 during a geographical cycle ; the fourth, geographical distribution — territorial 

 expansion or contraction. For a river's capture of territory is a phenomenon 

 capable of separate consideration from that of river phylogeny, though of course 

 it has an important bearing thereon. 



The author often speaks of the lives of streams. He implies thereby the 

 life throughout the geographical cycle. He speaks of young streams to imply 

 those existing at an early date of the cycle. But this seems to lead to a certain 

 want of precision, because one is apt to think of young streams as those near 

 the source — the head-waters — irrespective of the phase of development of the 

 geographical cycle. And so with other ages. A little reflection will show the 

 importance of making distinction between the growth of a stream itself, on its 

 way to the sea, and the sequence of phases which it exhibits as the geographical 

 cycle runs its course. 



These criticisms are not intended as fault-finding. They are to point 

 out how much may be gained by keeping the phases of river development 

 distinct. 



One fault, however, does run through this work. The author introduces a 

 term " corrasion " (p. 29) to denote "the deepening and widening of a stream 

 channel." Etymologically it is most unfortunate. For corrado means to scrape 

 or rake together. It might suitably be applied to the process whereby a 

 stream makes a gravel-bed ; it cannot denote the processes by which a stream 

 carries material away. 



The author is not responsible for the terms composed of combinations of 

 " sequent " which he uses. Yet these are unfortunate ; because they are apt to 

 clash with ordinary non-technical words, so that it is difficult to avoid saying, 

 not of course in a sentence, but on a page, that an obsequent stream arises 

 subsequent to and consequent on the growth of a subsequent, which is a 

 subsequent event to a consequent. It reminds me of a child's question — " Is a 

 donkey called a donkey because it is a donkey 1 " — a delightful confusion of 

 concrete, abstract, and qualitative senses of a word. 



Speaking of subsequent streams, the author does not fully discuss their 

 development (p. 185), partly for the reason that he only takes an outcrop 

 plain into consideration. In regard to obsequent streams he is certainly at 

 fault. He says, in effect, that when a stream is beheaded a portion of the 

 down side stream is reversed to make an obsequent. But the slope of the 

 channel would not permit this. What does happen is the result of a slow 

 process, of the growth of a new drainage, whereby an altogether new stream is 

 started. 



But though exception may be taken in such matters, the book may be 

 thoroughly commended as one which puts before the reader a most interesting- 

 amount of detail concerning river development. Particularly may it win 

 approbation for some charming photographs. Unfortunately the same cannot 

 be said for the maps ; they are not at all clear. S. 



