of boats. The Buduma islanders of Lake
Chad use clumsy skiffs eighteen feet long, made of hollow reeds tied
into bundles and then lashed together in a way to form a slight cavity
on top.[533] In the earliest period of Egyptian history this type of boat
with slight variations was used in the papyrus marshes of the Nile,[534]
and it reappears as the ambatch boat which Schweinfurth observed on the
upper White Nile.[535] It is in use far away among the Sayads or Fowlers,
who inhabit the reed-grown rim of the Sistan Lake in arid Persia.[536] As
the Peruvian balsa, it has been the regular means of water travel on
Lake Titicaca since the time of the Incas, and in more primitive form it
appears among the Shoshone Indians of the Snake River Valley of Idaho,
who used this device in their treeless land to cross the streams, when
the water was too cold for swimming.[537] Still cruder rafts of reeds,
without approach to boat form, were the sole vehicles of navigation
among the backward Indians of San Francisco Bay, and were the prevailing
craft among the coast Indians farther south and about the Gulf of Lower
California.[538] Trees abounded; but these remnant tribes of low
intelligence, probably recent arrivals on the coast from the interior,
equipped only with instruments of bone and stone, found the difficulty
of working with wood prohibitive.

The second step in the elaboration of water conveyance was made when
mere flotation was succeeded by various devices to secure displacement.
The evolution is obvious. The primitive raftsman of the Mesopotamian
rivers wove his willow boughs and osiers into a large, round basket
form, covered it with closely sewn skins to render it water-tight, and
in it floated with his merchandise down the swift current from Armenia
to Babylon. These were the boats which Herodotus saw on the
Euphrates,[539] and which survive to-day.[540] According to Pliny, the
ancient Britons used a similar craft, framed of wicker-work and covered
with hide, in which they crossed the English and Irish channels to visit
their kinsfolk on the opposite shores. This skin boat or coracle or
currach still survives on the rivers of Wales and the west coast of
Ireland, where it is used by the fishermen and considered the safest
craft for stormy weather.[541] It recalls the "bull-skin boat" used in
pioneer days on the rivers of our western plains, and the skiffs serving
as passenger ferries to-day on the rivers of eastern Tibet.[542