638 Mr. mann’s 'treat if e 
compared to that in the Seine, is lefs than it fhould be in. 
proportion to their refpedtive declivities, which is very 
juftly attributed to the much greater depth in proportion 
to the breadth of the Seine, above what is found in 
the Loire. This laft river is remarkably broad, and fo 
111 allow that in many places it is hardly navigable for 
boats. Now this, according to the principles laid down 
above (N° 27, 8ec.) muft very much diminifh the fwift- 
nefs of the current, which it fhould otherwife have from 
the great declivity of its bed. In confirmation of this it 
is moreover obferved, that in great falls of rain, which 
equally increafe the volume of water in both thefe rivers, 
the velocity in the Loire augments in a much greater 
proportion than it does in the Seine ; and this oblervation 
is likewife conformable to the principles above laid down 
(N° 12. 28. &c.). 
77. The river Doux, after paffing by Befanqon, falls 
into the Saone above Chalon; the Saone joins the Rhdne 
at Lyons. This river, from Befanyon to its mouth in the 
Mediterranean fea, is one of the raoft rapid in the known 
world : the velocity of its current is at leaft double to that 
of the Seine or Loire, and its courfe is almoft in a ftraight 
Hue. The difference of elevation of this river at Befan- 
qon, above that of its mouth in the Mediterranean fea, 
after a courfe of about eighty-fix French leagues, has 
been 
