SHORT NOTES. 215 



A commanding point, well fixed in the early part of the 

 route, may afford most valuable assistance in checking the work 

 further on. 



The difficulty, however, of identifying a peak on a range 

 of mountains from different points of view, is very great, and 

 considerable care and attention is required to turn such a feature 

 to good account. 



Altitudes. 



(IX.) — With regard to altitudes, much the some considera- 

 tions apply as in the case of the traveller's route. If possible, 

 some place of known height should be selected to start from ; 

 the series of observations should be unbroken, and should close 

 on some other place of known height. 



It is very desirable that the original observations should be 

 sent home to be worked out afresh. 



In any case the traveller should explain what datum point 

 he has taken, what height he has assig^ned to it, and on what 

 authority, what instruments he used, and how he took his obser- 

 vations. 



If any heights are entered on the sketch of his route, he 

 should append a note to say whether they denote relative heghts 

 or heights above sea level. 



Importance of mapping the drainage systems 

 met with. 



(X.) — Every effort should be made to delineate the drainage 

 system of the country. Even now it is not unusual to see 

 sketches of routes crossing rivers with nothing to show which 

 way the water flows. Whenev^er possible, the traveller should 

 state where the rivers rise and where they flow to. If it is 

 impossible for him to work this out himself, he may do much 

 from native information, while any notes he may make as to the 

 width and depth at various seasons will assist the identification. 



In many countries rivers have different names at various 

 points of their course, and it occasionally happens that the travel- 

 ler hits upon a river which he assumes, wrongly, to be some 

 well-known one, and which he, consequently, calls by that name. 

 To guard against confusion of this sort, he should always insert 

 the local native name, and if he identifies it with any other river 

 he should state his reasons for doing so. 



