The extreme rise and fall of the tide at the mouth of the river is 62 feet 3 inches. The usual rise and fall is from 8 to 12 feet less, depending on the stage of the river. At Fort Chimo the tide rises as much as 31 feet. The backwater is held in check as far as the upper rapids in a common stage of water, and during a high rise in the month of June the water is “backed” some 3 miles beyond the upper rapids. The branches of the Koksoak river are few and unimportant. The larger tributary is the Larch river. It is a rapid and almost unnavigable stream of variable depth, mostly shallow, and 100 to nearly 400 yards wide. At about 40 miles from its mouth the Larch forks, the lower or southwest fork draining the eastern sides of the same mountains whose western slopes are drained by the Little Whale river. This southwest fork of the Larch river is quite small and scarcely capable of being ascended, although it may, with great caution, be descended. This is the course followed by the Little Whale river Indians when they traverse the country to join the Naskopies of the Koksoak valley. The northwest branch of the Larch is still smaller and is reported to issue from the swampy tract of land in about latitude 58° 30´. The next large river is the Leaf. Its mouth is about 34 miles northwest of Fort Chimo, and it flows into a peculiarly shaped bay named Tass´iyak, or “like a lake.” The length of the river proper is estimated to be but 40 miles, flowing from a very long and narrow lake, having its longer axis extending southwestward and draining the greater part of the swampy tract lying in latitude 58° 30´. The southwestern portion of this tract is merely an area covered with innumerable small lakes so intimately connected by short water courses that it is difficult to determine whether water or land constitutes the greater part of the area. The rivers to the west are of less importance and drain the rugged area forming the northwestern portion of the district, or that part lying under the western third of Hudson strait. The principal portion of Hudson strait that came under my observation is Ungava bay. This bay is a pocket-shaped body of water lying south of the strait and toward its eastern end. Soundings in various portions of this bay indicate a depth of 28 to 70 fathoms for the central area. The bottom appears to be uniformly the washings from the freshwater streams. The extreme tides of Hudson strait tend to produce the most violent currents in this bay. Opposite the entrance of Leaf river bay is a whirlpool of considerable size, which causes much trouble to navigation. It is safe enough at high water but very dangerous at half-tide.