i8 PHYSIOGRAPHY. [chap. 



crossing these hills, then, we have passed from the basin of 

 the Thames into that of the Severn. The high land which 

 forms the divisional line between two contiguous river-basins 

 is called the water-parting. 



Instead of " water-parting," some writers employ the 

 term watershed ; but although the two words originally 

 meant precisely the same thing, the latter has become 

 rather ambiguous. " Watershed " is a word which has been 

 borrowed from German geographers. The verb scheiden 

 signifies " to separate," and die Wasserscheide is simply the 

 "water- separation " or the "parting of the waters" — the old 

 Divortitmi- aquarum. But many writers, looking at the 

 common meaning of the English verb " to shed " have 

 used the term "watershed" to denote the surface from 

 which the waters are shed, or the slope along which they 

 flow ; hence it is not uncommon to hear such expressions 

 as " the crest of the watershed." To avoid this double use 

 of the word "watershed," the term "water-parting" has 

 been introduced as the English equivalent of the German 

 Wasserscheide, or the boundary-line between two adjacent 

 river-systems. Such a line was called by Professor Phillips 

 " the summit of drainage ; " and in the north of England, 

 where it often separates one estate from another, it is known 

 as " the heaven-water boundary." To avoid all ambiguity 

 it is perhaps best to set aside the original meaning of 

 " watershed," and employ the term to denote the slope 

 along which the water-flows, while the expression "water- 

 parting " is employed for the summit of this slope. Thus 

 the ridge of a roof is the water-parting ; and the slates or 

 tiles on each side, down which the water drains, will form 

 the watershed. It must be remembered, however, that the 

 water-parting is not necessarily the summit of a range of 

 hills, like the ridge of a roof. Frequently, indeed, the 



