bridges, repeating this several times, as the rocks and jungle
rendered it very difficult to do it accurately: then, sitting on the
bridge, I timed floating masses of different materials and sizes that
were thrown in at the upper point. I was surprised to find the
velocity of the Lachen only nine miles per hour, for its waters
seemed to shoot past with the speed of an arrow, but the floats
showed the whole stream to be so troubled with local eddies and
backwaters, that it took from forty-three to forty-eight seconds for
each float to pass over 200 yards, as it was perpetually submerged by
under-currents. The breadth of the river averaged sixty-eight feet,
and the discharge was 4,420 cubic feet of water per second.
The temperature was 57 degrees.

At the Lachoong bridge the jungle was still denser, and the banks
quite inaccessible in many places. The mean velocity was eight miles
an hour, the breadth ninety-five feet, the depth about the same as
that of the Lachen, giving a discharge of 5,700 cubic feet of water
per second;* [Hence it appears that the Lachoong, being so much the
more copious stream, should in one sense be regarded as the
continuation of the Teesta, rather than the Lachen, which, however,
has by far the most distant source. Their united streams discharge
upwards of 10,000 cubic feet of water per second in the height of the
rains! which is, however, a mere fraction of the discharge of the
Teesta when that river leaves the Himalaya. The Ganges at Hurdwar
discharges 8000 feet per second during the dry season.] its
temperature was also 57 degrees. These streams retain an
extraordinary velocity, for many miles upwards; the Lachen to its
junction with the Zemu at 9000 feet, and the Zemu itself as far up as
the Thlonok, at 10,000 feet, and the Lachoong to the village of that
name, at 8000 feet: their united streams appear equally rapid till