excavation--a serious matter in those days. The difficulty was overcome
by locking up at the upper or western end 13 feet and down 23 at lower
end, supplying the summit by a 'feeder from a small stream called the
North River, which empties into the Ottawa three or four miles below
Carillon, but is close to the main river opposite the canal.

In 1870-71 the Government of Canada determined to enlarge these canals
to admit of the passage of boats requiring locks 200 feet long, 45 feet
wide, and not less than 9 feet of water on the sills at the lowest
water. In the case of the Grenville Canal this was and is being done by
widening and deepening the old channel and building new locks along
side of the old ones. But to do that with the Carillon was found to be
inexpedient. The rapidly increasing traffic required more water than the
North River could supply in any case, and the clearing up of the country
to the north had materially reduced its waters in summer and fall, when
most needed. To deepen the old canal so as to enable it to take its
supply from the Ottawa would have caused the excavation of at least
1,250,000 cubic yards of rock, besides necessitating the enlargement of
the Chute a Blondeau also.

It was therefore decided to adopt a modification of the plan proposed
by Mr. T.C. Clarke, of the present firm of Clarke Reeves & Co, several
years before when he made the preliminary surveys for the then proposed
"Ottawa Ship Canal," namely to build a dam across the river in the
Carillon Rapid but of a sufficient height to drown out the Chute a
Blondeau, and also to give the required depth of water there.

During the summer and fall of 1872 the writer made the necessary surveys
of the river with that end in view. By gauging the river carefully in
high and low water, and making use of the records which had been kept by