168 ROYAL SOCIETY OF CANADA 
quarter long, and not over a quarter of a mile at its greatest width. At 
the upper or western end of this lake, the river is contracted in two 
places to a width of less than a hundred feet, and a fall of nearly twenty 
feet is occasioned by the Plein-Chant Rapids. The fall is in two descents 
with an intervening stretch of quiet water, the larger one near Boom 
Lake alone having to be “ portaged.” Lake Plein-Chant, at the head of 
these rapids, is a beautiful stretch of deep water, five and a half miles in 
length. The widest portion is near the eastern end, where it is about thirty 
chains, but this gradually diminishes westward till near the upper end 
it is not more than three or four chains wide. In the wider portion the 
sounding lead indicated a depth of over two hundred and eighty feet. 
Between this lake and Lac des Aiguilles, as the next expansion is called, 
the distance is a little over two miles and four rapids intervene with 
alternating stretches of still water, the combined fall of “which is 
eighteen feet. The three largest rapids are known in ascending order as 
“ Les Hpines,” “La Rose” and “des Rochers” or “des Aiguilles.” The 
Amable du Fond River, the largest tributary of the Mattawa, enters from 
the south side a short distance above the second rapid. We next come 
to Lac des Aiguilles which is a little over a mile long and a quarter of a 
mile wide. It is separated from the next succeeding stretch of river lying 
parallel to it on the north side, by a rocky bar known as “ Les Aiguilles” 
Islands. The three narrow rocky channels formed by these two islands 
even at high water barely afford a passage to loaded canoes. The eastern 
one constitutes the main connection, and a small rapid at this point shows 
a descent of a few inches. Above this we enter a long stretch of deep 
water which gradually diminishes in width as we ascend. ‘The river 
throughout this distance of two and a half miles is flanked on either side 
by almost perpendicular walls of gneissoid granite, which, in the narrower 
places especially, give it the aspect of a beautiful natural canal. At the 
end of this stretch, the upward course of the river changes sharply to a 
southerly direction for about two miles, and the progress of navigation is 
obstructed by a series of rapids, with intervals of deep water, the total fall 
in this distance being fifty-five feet. The Chute des Paresseux, where the 
water of the river is precipitated in a beautiful fall thirty-four feet in 
height, is the first and greatest of this series of interruptions encountered 
in the ascent of the stream. Pimisi or Eel Lake, above these rapids, marks 
another change in the course of the stream, and from this place to the 
head of Talon Lake it maintains a northwesterly direction. Between 
Pimisi Lake and the Talon Chute the river flows for three-quarters of a 
mile through a narrow rocky cañon inclosed between perpendicular walls 
of granite. At the Talon Chute, which is the greatest single fall on the 
whole river, the water is precipitated a distance of forty-three feet over a 
rocky ledge composed of massive flesh-red gneissoid granite. The main 
channel is on the north side, but, in addition, there is another though much 
