At Fort Simpson, during the decade of 1876-1886, the drift ice was seen as early as October 11, in 1884, and as late as November 12, in 1879. The earliest date at which the river closed was November 17, in 1876, and the latest was November 30, in 1882. The earliest date at which the ice broke up was May 1, in 1883, and the latest May 14, in 1876. LANDMARKS ALONG THE MACKENZIE. Some notes culled from Mr. Ogilvie’s report as to the principal tributaries of the Mackenzie between Great Slave lake and the sea, and as to a few of the more remarkable stretches of the main river, will prove interesting at this point. Seventy miles below Great Slave lake is Little lake, which is about twelve miles long and ten to twelve miles wide, being merely an expansion of the river, like Lakes St. Francis and St. Peter in St. Lawrence system. Thirty-six miles lower down, Yellowknife river enters the Mackenzie from the south. It would appear from the statements of Indians to Mr. Ogilvie that this is the largest tributary of the Mackenzie between the Liard and Fort Providence. Twenty-seven miles below the confluence of the Yellowknife, and continuing to a short distance above the confluence of the Liard, the Mackenzie narrows to an average width of a little over half a mile, with a generally swift current. This continues for seventy and a half miles or nearly as far as Fort Simpson, near the mouth of the Liard and causes this part of the river to be called “The Line,” from the fact that large boats cannot be rowed against the current, but have to be hauled by a line attached to them, and pulled by men on shore. This is the common mode of navigation on all the northern rivers where there are no steamers, as it is less laborious than rowing against a current. By the survey it is seven hundred and fifty-eight and one-half miles from Fort Simpson to Fort McPherson. The former fort is situated on an island just below the junction of Mackenzie and Liard rivers. Ninety miles below Fort Simpson, on the west side, a river flows in from the southwest. Mr. Ogilvie had seen its name spelled Na-hone, but remembered that it is spelled by the Reverend Father Petitot, Na-hauner. It is, however, now known as North Nahanni river. This stream, as seen from the opposite side of the river, seems about two hundred yards wide, but it is shallow and rough at the mouth as was ascertained by the noise of its waters being plainly heard across the Mackenzie, here a mile wide. Mr. Ogilvie could get no information as to what it was like for any distance above its mouth, but it pierces the range of mountains to the west, which here come close to the river. The valley thus formed can be seen extending southwesterly through the mountains for many miles. The banks in the stretch of the Mackenzie from Simpson to this point are alternately low and swampy and moderately high, consisting of gravel and sand. SOME TRIBUTARIES.