“CLEVELAND, O., March 28, 1866. “Turtle Lake, at the head of Turtle River, which discharges into Cass Lake, is the most northerly of the waters of the Mississippi. Mr. Schoolcraft claims that Itasca Lake and its tributaries constitute the true source of the Great River, because these streams are further from the mouth than any other. Whether this, if true, is a correct mode of fixing the head waters of rivers, I must be allowed to doubt. It seems to me that the _largest_ branch forms the river, and the heads of that branch constitute the sources. “When I was on the upper waters of the Mississippi, in September 1848, I compared the quantity of water flowing from Lake Winnibigoshish with that from Leech Lake, as far as observations without gauging enabled me to do it. At that time I judged the discharge from the Leech Lake branch to be three times as much as from Lake Winnibigoshish, and one of our voyageurs, who was raised in the region, said it generally discharged twice as much. The distance from the junction of the Leech Lake branch, below Winnibigoshish, to the most distant sources of the various branches, does not appear to me to be materially different. Among the hundreds of small streams converging into, and passing through nearly as many lakes, there cannot be said to be a main or separate river above this junction. From this point, the Mississippi assumes its proper characteristics, as one stream, to the gulf of Mexico; but above it, the branches are excessively numerous. Below the junction, it is two chains wide, with a broad regular current, having the same imposing features which it retains to its mouth. The furthest streams that discharge into Leech Lake rise to the south, interlocking with the waters of Pine River; but, if we can rely upon our maps—of a region as yet unsurveyed—the development of these branches, including the lakes through which they pass, equals in length the Itasca branch. “Our missionaries at Cass Lake said the Turtle River discharged more water than Bemidji River, which enters Cass Lake from Itasca Lake.” HISTORICAL NOTES OF THE UNITED STATES LAND OFFICE. [By Hon. H. M. Rice, of St. Paul.]