in its relation to Agricnlture. 
427 
tlircctlv into the ocean : the Scvre, which flows almost exclusively 
through J urassic strata ; and the Charente which waters districts 
chiefly belonging to the lower chalk formation. These two rivers 
converge at their outlet into the sea, opposite the Isle of Rhe. 
Finall}', in the extreme south the river Adour, flowing from the 
western extremity of the Pyrenean chain, empties its waters into 
the Bav of Biscay at Bayonne, close to the Spanish seaboard. 
The whole length of the river Loire exceeds 800 miles. It 
drains at least one-fourth of the whole surface of French terri- 
tory. Its sudden fieaks and temfic overflowings are too well 
known to need more than a passing notice. I shall refer in a 
subsequent paragraph to the nature of its waters and that of its 
principal affluents. 
The Gironde, together with its two great affluents, the Dor- 
dogne and the Garonne, drain an area of at least twelve million 
acres. 
The river Rhone is, so to speak, the only channel through 
which all the waters of the immense Mediterranean basin are 
conveyed into the sea. I have already described the boundaries 
of that extraordinary water division, so boldly and so strikingly 
delineated by the lofty range of mountains which surround it on 
all sides, from the eastern extremity of the Pyrenees to the 
southern buttresses of the Alps on the western limit of the 
Gulf of Genoa. 
The river Rhone takes its source in one of the glaciers of the 
Saas Mountains west of St. Gothard, at an altitude of nearly 
GOOO feet above the level of its mouths. The length of its 
course, including its passage through the Lal:e of Geneva, from 
which it gushes forth purified and refreshed like a mighty giant, 
is no less than 600 miles. Its principal affluents are the Arve, 
just below Geneva, which brings all the water from the western 
slopes of the Savoisian Alps, from the heights of Mont Blanc, and 
the river Ain, which drains the whole of the ancient province of 
Bresse. At Lyons the Rhone enters the valley of the placid but 
treacherous Saone. Lower down the Isere brings down the 
waters collected from the deep valleys of Maurienne up to the 
Mont Cenis, and then gathers those of the Cottian Alps as it 
traverses the luxuriant valley of Graisivaudan, by Grenoble, and 
the Grande Chartreuse. Last in order come the Drome and the 
unruly Durance. 
The noble Rhone is then the main, if not the only, outlet of 
the waters of the Mediterranean basin ; and, together with the 
Saone, which can hardly be termed its affluent, is the charac- 
teristic feature of the whole division. Nothing can be more 
striking than the contrast presented by these rivers : the one 
owing its origin to, and being fed by, torrential affluents, preserves 
VOL. XXII. 2 c; 
