THE CANAL

The canal was formed by "fencing in" a portion of the river-bed by an
embankment built about a hundred feet out from the north shore and
deepening the intervening space where necessary. There are two
locks--one placed a little above the foot of the rapid (see map), and
the other at the end of the dam. Wooden piers are built at the upper and
lower ends--the former being 800 ft. long, and the latter 300 ft; both
are about 29 ft. high and 35 ft. wide.

The embankment is built, as shown by the cross section, Fig. 6. On the
canal side of it there is a wall of rubble masonry F, laid in hydraulic
cement, connecting the two locks, and backed by a puddle wall, E, three
feet thick; next the river there is crib work, G, from ten to twenty
feet wide and the space between brick-work and puddle filled with earth.
The outer slope is protected with riprap, composed of large bowlders.
This had to be made very strong to prevent the destruction of the bank
by the immense masses of moving ice in spring.

The distance between the locks is 3,300 feet.

In building the embankment the crib-work was first put in and followed
by a part (in width) of the earth-bank. From that to the shore temporary
cross-dams were built at convenient distances apart and the space pumped
out by sections, when the necessary excavation was done, and the walls
and embankments completed. The earth was put down in layers of not more
than a foot deep at a time, so that the bank, when completed, was solid.
The water at site of it varied in depth from 15 feet at lower end to 2
feet at upper.