166 ROYAL SOCIETY OF CANADA 
culty at any time being presented by the small rapid known as the 
Chenaux, about four miles below that place, where there is a fall of from 
eight to ten inches only in the ordinary stage of water in the river. This 
stretch brings us to the foot of the chain of rapids and falls known as 
the Darges, the Mountain, the Sable, and the Grand Calumet, the whole 
extending for a distance of ten miles, in which there is a total descent of 
ninety-three feet, and bringing us to the town of Bryson, on the north 
channel of the river past Calumet Island. 
The river westward from Bryson presents no difficulties to steamboat 
navigation other than those caused by shifting sand-bars for about thirty 
miles, or to the foot of Allumette Island, which is at the upper end of 
Lake Coulonge. The shores of this portion of the river along the north 
channel of Calumet Island are generally low and composed of sand, 
with rock ledges at but few points; but the south or Roche Fendue chan- 
nel is much more broken, heavy rapids and pitches occurring for some 
miles or to within about three miles of the head of the island. At the 
foot of Allumette Island two channels of the Ottawa unite. On the 
south channel the navigation is obstructed by two rapids, the Paquette 
and the Allumette, the former at the lower end of Allumette Island 
near the junction with the north channel, and the latter about three miles 
below the town of Pembroke. These present a well-defined barrier to the 
navigation of this channel, though the fall in either of the rapids is not of 
great amount; while in the north channel the obstructions caused by 
LIslet and Culbute rapid and fall are overcome by a lock, constructed 
about twenty years ago, by which a total descent in the river of eighteen 
feet is overcome. By this means continuous steamboat communication is 
secured from Bryson to the foot of the Des Joachims Rapids, a distance in 
all of seventy-seven miles, and steamers ply regularly between the town of 
Pembroke and the latter point. The portion of the Ottawa for thirty miles 
below the Des Joachims Rapids is known as the Deep River, the stream 
flowing in a nearly straight course between generally lofty hills of reddish 
syenite and granitic gneiss. The water along this portion is generally 
very deep, and the river presents magnificent stretches of the grand 
scenery found in the Laurentian hills, resembling in this respect to a great 
extent the gorge-like aspect of the Saguenay. 
From the Des Joachims,to the forks of the Mattawa the distance is 
only fifty-two miles, and in this stretch the navigation is broken by the 
Joachim itself, with a fall of twenty-eight feet in two miles, above which 
the course is clear for sixteen miles to Rocher Capitaine rapid and fall, one 
of the finest in the river, the descent here being forty-five feet and the 
obstruction extending for two miles. In the stretch between these two 
rapids the waters of the stream have a fall of eight feet, in which is 
included MecSorley’s Rapid, with a fall of almost three feet, sufficient to 
impart a perceptible current, but otherwise offering no hindrance to con- 
