the Appalachian wall.  They opened up only restricted fur fields which were soon exhausted, so that the migrant trapper was here early converted into the agricultural settler, his shifting camp fire into the hearthstone of the farmhouse.  Expansion was slow but solid.  The relatively small area rendered accessible by their streams became compactly filled by the swelling tide of immigrants and the rapid natural increase of population.  In sharp contrast to this development, the long waterway of the St. Lawrence and the Great Lakes leading to the still vaster river system of the Mississippi betrayed the fur-trading French into excessive expansion, and enabled them to appropriate but not to hold a vast extent of territory.  A hundred years after the arrival of Champlain at Montreal, they were planting their fur stations on Lake Superior and the Mississippi, 1,400 miles (2,300 kilometers) back from the coast, at a time when the English settlements had advanced little beyond tide-water.  And when after 1770 the westward movement swept the backwoodsmen of the English colonies over the Appalachian barrier to the Ohio, Cumberland and Tennessee, these long westward flowing streams carried them rapidly on to the Mississippi, communicated the mobility and restlessness of their own currents to the eager pioneer, and their capacity to master great distances; so that in forty short years, by 1810, settlements were creeping up the western tributaries of the Mississippi.  The abundant water communication in the Mississippi Valley, which even for present large river craft contains 15,410 miles of navigable streams and which had therefore a far greater mileage in the day of canoe and flatboat, afforded outlet for bulky, backwoods produce to the sea at New Orleans.  When the English acquired Canada in 1763, they straightway fell under the sway of its harsh climate and long river systems, taking up the life of the fur trader; they followed the now scarcer pelts from the streams of Superior westward by Lake Winnipeg and along the path of the Saskatchewan River straight to the foot of the Rockies.

[Sidenote:  Siberian rivers and Russian expansion.]

Rivers have played the same part in expediting Russian expansion across the wide extent of Siberia.  Here again a severe climate necessitated reliance on furs, the chief natural product of the country, as the basis of trade.  These, as the outcome of savage economy, were gathered in from wide areas which only rivers could open up.  Therefore, where the Siberian streams flatten out their upper courses east and west against the northern face of the Asiatic plateau, with low watersheds between, the Russian explorer and sable hunter struck their eastward water trail toward the Pacific.  The advance, which under Yermak crossed the Ural Mountains in 1579, reached the Yenisei River in 1610 and planted there the town of Turuchansk as a sort of milestone, almost on the Arctic Circle opposite the mouth of the Lower Tunguska,