484 TRANSACTIONS OF SECTION E. 



explorer's observatioas should contribute most largely, and where therefore their 

 material should be utilised with the best results. Even here there is room for 

 much more work of the detailed and critical type, which is not merely general 

 and descriptive, but starts from the careful collection of data, proceeds to the 

 critical discussion of them, and continues by a comparison of the results with 

 those obtained in similar observations in other regions. 



To take a single branch of Physical Geography, the study of Eivers, the 

 amount of accurate material which has been adequately discussed is small. In 

 our own country the rainfall of various river basins is well known through the 

 efforts of a meteorological Association, but the proportion of it which is removed 

 by evaporation, and of that which passes into the soil, has only been very 

 partially studied. Passing to the run-off, which is more easy to determine satis- 

 factorily, the carefully measured discharges of streams and rivers are not nearly 

 so numerous as they should be if the hydrography of the rivers is to 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 fina.1 

 value but without 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 requires the more detailed information if he _ is 

 to co-ordinate satisfactorily the volume discharged with local rainfall, 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 under- 

 taken 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 

 jjiece of work may be, I should much prefer to see the hydrography of a tribu- 

 tary of a river system worked out by a geographer 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 centred in these subjects. 



In the same way we still know too little of the amounts of the dissolved and 

 suspended 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 provide the opportunity for 

 much useful study, which may be extended as information 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 movement of flood waves, in determining the amount of matter transported 

 both in suspension 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 ascei-taining the loss of water by seepage in various parts of its 

 course, and generally in studying tlic hundred 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 account 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 

 oTi some of the English lakes, so that excellent examples of how such work 

 should lie done are available as a guide to anyone who will devote his spare 

 time for a year or two in making a thorough acquaintance with the charac- 

 teristics and phenomena of any lake to which he has access. 



Coast-lines provide another class of geographical control which repay."; 

 detailed study, and presents numberless opportunities for systematic investiga- 



