October 29, 1915] 



SCIENCE 



593 



be adequately discussed; for although the 

 more important rivers have been gauged 

 by the authorities responsible for them in 

 many cases, the results have usually been 

 filed, and the information which has been 

 published is usually a final value but vrith- 

 out either the original data from which it 

 has been deduced, or a full account given 

 of the methods of measurement which have 

 been employed. For the requirements of 

 the authority concerned such a record is 

 no doubt adequate, but the geographer re- 

 quires the more detailed information if he 

 is to coordinate satisfactorily the volume 

 discharged with local rainfaU, with changes 

 in the rates of erosion or deposition, and 

 the many other phenomena which make 

 up the life-history of a river. Here too it 

 is usually only the main stream which has 

 been investigated; the tributaries still 

 await a similar and even fuller study. A 

 valuable contribution to work of this kind 

 exists in the hydrographical study of the 

 Medway and of the Exe which has been 

 undertaken by a committee of the Royal 

 Geographical Society during recent years, 

 and this may serve as a guide to other 

 workers; but, however welcome such a 

 piece of work may be, I should much pre- 

 fer to see the hydrography of a tributary 

 of a river system worked out by a geog- 

 rapher as a piece of individual work, just 

 as the geology or the botany or the zoology 

 of a single restricted area is investigated 

 by those whose interests are centered in 

 these subjects. 



In the same way we still know too little 

 of the amounts of the dissolved and sus- 

 pended matter which is carried down by 

 our streams at various seasons of the year 

 and in the different parts of their course. 

 This class of investigation does not need 

 very elaborate equipment, and may pro- 

 vide the opportunity for much useful 

 study, which may be extended as infor- 



mation is increasingly acquired. In this 

 way when numerous individual workers 

 have studied the conditions prevailing in 

 their own areas, and traced them through 

 their seasonal and yearly variations, we 

 shall possess a mass of valuable data with 

 which we may undertake a revision of the 

 results which have been arrived at in past 

 years by various workers from such data 

 as were then at their disposal. 



In this one branch of the subject there 

 is ample scope for workers of all interests 

 in the measurement of discharges, in the 

 determination of level, and of the move- 

 ment of flood waves, in determining the 

 amount of matter transported both in sus- 

 pension and in solution, in tracing out the 

 changes of the river channel, in following 

 out the variation of the water-table which 

 feeds the stream, in ascertaining the loss 

 of water by seepage in various parts of its 

 course, and generally in studying the hun- 

 dred other phenomena which are well 

 worth investigating, and which give ample 

 scope for workers of all kinds and of all 

 opportunities. There is work not only in 

 the field, but also in the laboratory and in 

 the library which needs doing, for the full 

 accoimt of even a single stream can only 

 be prepared when data of all classes have 

 been collected and discussed. 



On the Scottish lakes much valuable 

 scientific work has been done, and also on 

 some of the English lakes, so that excellent 

 examples of how such work should be done 

 are available as a guide to any one who 

 will devote his spare time for a year or 

 two in making a thorough acquaintance 

 with the characteristics and phenomena of 

 any lake to which he has access. 



Coast-lines provide another class of geo- 

 graphical control which repays detailed 

 study, and presents numberless opportun- 

 ities for systematic investigation and ma- 

 terial for many profitable studies in geog- 



