one-fourth that of Brazil but a railroad mileage nearly one-fourth
greater, have been pushed to this development primarily by a common lack
of inland navigation. Similarly South Africa, stricken with poverty of
water communication south of the Zambesi, has constructed 7500 miles of
railroads[678] in spite of the youth of the country and the sparsity of
its white population. Similar geographic conditions have forced the
mileage of Australian railways up to twice that of South Africa, in a
country which is still in the pastoral and agricultural stage of
development, and whose most densely populated province Victoria has only
fourteen inhabitants to the square mile. In the almost unpeopled wastes
of Trans-Caspia, where two decades ago the camel was the only carrier,
the Russian railroad has worked a commercial revolution by stimulating
production and affording an outlet for the irrigated districts of the
encircling mountains.[679] In our own Trans-Missouri country, where the
scanty volume of the streams eliminated all but the Missouri itself as a
dependable waterway, even for the canoe travel of the early western
trappers, railroads have developed unchecked by the competition of river
transportation.[680] With no rival nearer than the Straits of Magellan
and the Isthmus of Panama for transportation between the Mississippi and
the Pacific coast, they have fixed their own charges on a monopoly
basis, and have fought the construction of the Isthmian Canal.

[Sidenote: Unity of a river system.]

A river system is a system of communication. It therefore makes a bond
of union between the people living among its remoter sources and those
settled at its mouth. Every such river system forms geographically an
unbroken whole. Only where a wild, torrent-filled gorge, like the
Brahmaputra's path through the Himalayas, interrupts communication
between the upper and lower course, is human life in the two sections
divorced. But such cases are rare. Even the River Jhelam, which springs
with mad bounds from the lofty Vale of Kashmir through the outer range
of the Himalayas down to its junction with the Indus, carries quantities
of small logs to be used as railway sleepers; and though it shatters a
large per cent. of them, it makes a link between the lumber men of the
Kashmir forests and British railroad engineers in the treeless plains of
the Indus.[681]

[Sidenote: The effect of common water supply in arid lands.]

In arid lands, wher