diverted from their courses, and they are often carried long
distances out of their natural way. The second method is to divert a
part of a river by means of a stone dam. The third method is still more
artificial than the preceding -- the water is lifted by direct human
power from below the sementera and poured to run over the surface.

The first method is the most common, since the mountains in Igorot land
are full of small, usually perpetual, streams. There are practically no
streams within reach of suitable pueblo sites which are not exhausted
by the Igorot agriculturist. Everywhere small streams are carefully
guarded and turned wherever there is a square yard of earth that may
be made into a rice sementera. Small streams in some cases have been
wound for miles around the sides of a mountain, passing deep gullies
and rivers in wooden troughs or tubes.

Much land along the river valleys is irrigated by means of dams, called
by the Igorot "lung-ud'." During the season of 1903 there was one dam
(designated the main dam in Pl. LVII -- see also Pls. LV and LVI)
across the entire river at Bontoc, throwing all the water which did
not leak through the stones into a large canal on the Bontoc side of
the valley. Half a mile above this was another dam (called the upper
dam in Pl. LVII) diverting one-half the stream to the same valley,
only onto higher ground. Immediately below the main dam were two low
piles of stones (designated weirs) jutting into the shallow stream
from the Bontoc side, and each gathering sufficient water for a few
sementeras. Within a quarter of a mile below the main dam were three
other loose, open weirs of rocks, two of which began on a shallow
island, throwing water to the Samoki side of the river. In the stream
a short distance farther down a shallow row of rocks and gravel turned
water into three new sementeras constructed early in the year on a
gravel island in the river.

The main dam is about 12 feet high, 2 feet broad at the top, 8 or
10 at the bottom, and is about 300 feet long. It is built each year
during November and December, and requires the labor of fifteen
or twenty men for about six weeks. It is constructed of river-worn
bowlders piled together without adhesive. The top stones are flat on
the upper surface, and the dam is a pathway across the river for the
people from the time of its completion until its destruction by the
freshets of June or July.

The upper dam is a new piece of prim