The northern branch of the Ohio, known as the Alleghany River, has a length of four hundred miles, and its source is in the county of Potter, in northern Pennsylvania. It takes a very circuitous course through a portion of New York state, and re-enters Pennsylvania flowing through a hilly region, and at the flourishing city of Pittsburgh mingles its waters with its southern sister, the Monongahela. The region traversed by the Alleghany is wild and mountainous, rich in pine forests, coal, and petroleum oil; and the extraction from its rocky beds of the last-named article is so enormous in quantity, that at the present time more than four million barrels of oil are awaiting shipment in the oil districts of Pennsylvania. The smaller steamboats can ascend the river to Olean, about two hundred and fifty miles above Pittsburgh. At Olean, the river has a breadth of twenty rods. In consequence of its high latitude, the clear waters of the Alleghany usually freeze over by the 25th of December, after having transported upon its current the season's work, from the numerous saw-mills of the great wilderness through which it flows, in the form of rafts consisting of two hundred million feet of excellent lumber. The Ohio River has a width of about half a mile below Pittsburgh, and this is its medial breadth along its winding course to its mouth at Cairo; but in places it narrows to less than twenty-five hundred feet, while it frequently widens to more than a mile. A geographical writer says, that, "In tracing the Ohio to its source, we must regard the Alleghany as its proper continuation. A boat may start with sufficient water within seven miles of Lake Erie, in sight sometimes of the sails which whiten the approach to the harbor of Buffalo, and float securely down the Conewango, or Cassadaga, to the Alleghany, down the Alleghany to the Ohio, and thence uninterruptedly to the Gulf of Mexico." There are grave reasons for doubting that part of the statement which refers to a boat starting from a point within seven miles of Lake Erie. It is to be hoped that some member of the New York Canoe Club will explore the route mentioned, and give the results of his investigations to the public. He would need a canoe light enough to be easily carried upon the shoulders of one man, with the aid of the canoeist's indispensable assistant--the canoe-yoke. It will be seen that the Ohio with its affluents drains an immense extent of country composed of portions of seven large states of the Union, rich in agricultural wealth, in timber, iron, coal, petroleum, salt, clays, and building-stone. The rainfall of the Ohio Valley is so great as to give the river a mean discharge at its mouth (according to the report of the United States government engineers) of one hundred and fifty-eight thousand cubic feet per second. This is the drainage of an area embracing two hundred and fourteen thousand square miles.