from perpendicular falls. Though originating in, and having its entire course amongst craggy mountains, it is navigable at high water to near Bedford.

The Potomac derives but a small portion of its waters from Pennsylvania. It has its sources in nearly the highest table land of the Appalachian system.

Like those of the Delaware and Susquehanna, the great confluents of the Potomac, are from the right bank.

Savage river and Will's creek from Allegheny, Conecocheague from Washington, and Monocacy from Frederick county in Maryland, are comparatively trivial, when compared with the branches of Potomac derived from Virginia.

At Cumberland, the Potomac reaches within five, and at Hancock within two miles of the south boundary of Pennsylvania.

Leaving the Atlantic slope, we perceive a great river valley stretching from Pocahontas county, Virginia, over western Pennsylvnnia into New-York. This valley extends nearly due north and south at an angle of about forty-five degrees, to the range of the Appalachian mountains, and reaches from North Latitude, 38° 30 to North Latitude 42° 20. The extremes giving sources to two rivers that of the north to the Allegheny, and that of the south to the Monongahela. These streams flowing directly towards each other meet at Pittsburg very nearly at the middle point of the valley. Their united waters taking the name of Ohio turns to the west, or rather northwest, as far as the entrance of Big Beaver river. With a very partial exception, western Pennsylvania is drained by the Allegheny and Monongahela.

Having its source in Potter county in Pennsylvania, and interlocking with the head branches of the Susquehanna and Genessee, the Allegheny flows northwest about fifty miles into Cataraugus county, New-York. Abrubtly

turning to southwest and preserving that general course one hundred miles, and receiving French creek from the northeast, it thence bends to southeast forty miles, to the mouth of Mahoning. About the middle of the latter course, Clarion river and Red Bank creek, two large branches, enter from the northeast. From Mahoning to Pittsburg, the general course is again southwest about fifty miles.*

Kiskiminitas, a very considerable accessory stream of the Allegheny river, rises in the mountain valley, between the Allegheny and Chesnut Ridge chains, and flowing northwest, breaks through Chesnut and Laurel Hill, and after a comparative course of seventy-five miles, unites with the Allegheny, near midway between the mouth of Mahoning and Pittsburg. From the mouth of this river the state canal extends along its valley, and that of the Conemaugh (another name for the sume stream) to Johnstown, a distance of about 70 miles.

Mahoning and Red Bank creeks have their sources in Chesnut Ridge, and with each a course of about thirtyfive miles, the former northwest and the latter southwest, join the Allegheny in Armstrong county. Toby's creek, or Clarion river, has interlocking sources with those of Sinnemahoning and the Allegheny river. The Red Bank rises in the same region with Clarion river and Sinne. mahoning; and Mahoning with Red Bank, and the west branch of the Susquehanna.

In point of surface drained, Kiskiminitas is the largest cofluent of the Allegheny, and it has interlocking sources with those of the west branch of the Susquehanna, Juniata and Youghiogheny.

*The state canal runs along the west bank of the river from opposite the mouth of the Kiskiminitas to Pittsburg, somewhat more than 30 miles.

Allegheny river receives but two considerable tributaries from the right, French and Conewango creeks. The latter rises in Chataque county, New York, by three branches; the Chataque, Casadauga, and Conewango, which unite in New York, and forming a navigable stream, assume a south course, enter Warren county, Pennsylvania, and fall into the Allegheny, at the town of Warren, after a comparative course of about forty-four miles.

French creek has its source in the extreme southwest angle of New York, and increased by numerous branches from Erie and Crawford counties, Pennsylvania, forms a navigable river at Meadville. Flowing to the southeast from Meadville 25 miles, it unites with the Allegheny river at Franklin in Venango county. The entire comparative course of French creek is about eighty miles. Along this stream the state canal has been finished about thirty miles towards the mouth.

There is no other feature in the hydrography of the United States more remarkable than the country from which Chatauque and French creeks have their sources. The extreme north west waters of the former flow from within three, and of the latter, from within five miles of the margin of Lake Erie.

The Allegheny and its branches are the recipients of the nerthern part of the great western basin of Pennsylvania, and are but little impeded by falls, though their current is rapid.

The Monongahela, formed by two branches, the Monongahela proper, and Cheat river, which rise in Pocahontas, Randolph, Harrison, Lewis, Monongahela and Preston counties of Virginia, and unite, two miles within the south boundary of Pennsylvania. Their general length above Pennsylvania, is about one hundred miles, nearly a north course. Preserving the latter direction sixty miles

leaves Pennsylvania, and enters into Ohio. Within the latter state, the Ohio river inflects to a course a little west of south, seventy miles; reaching in that direction, nearly the same latitude with the south boundary of Pennsylvania.

The peculiar courses of the Monongahela and Ohio, form one of the most remarkable intermediate peninsulas presented by the topography of the United States. The two streams flow in very nearly opposite directions, the intervening space being from thirty-five to forty miles wide, with a mean length of sixty miles. Though hilly, rather than mountainous, this peninsula is elevated to from six hundred to one thousand feet in the dividing line of its waters, above the adjacent rivers. A number of creeks, none of which can exceed a comparative course of twenty-five miles, are poured from the interior spine into the respective recipients. The dividing ridge is evidently continued north of the Ohio river, broken by that stream a few miles below Pittsburg. The northern section is continued, inflecting between the western sources of the Allegheny, and the eastern sources of Big Beaver river, and is finally lost on the southeastern shores of lake Erie; the southern, stretching between the confluents of the Ohio and Monongahela rivers, mingles with the Appalachian chains between the sources of the latter and the little Kenhawa. This ridge is the western buttress of the upper basin of Ohio, and affords a very striking example of the real difference between a chain of hills and one of mountains. The ascent by the rivers to the western ridge of Pennsylvania is so gradual, and the hills scattered in such promiscuous windings through the sources of the streams, that an ascent of six or seven hundred feet, in a few miles, is imperceptible; on the contrary, the mountain chains extend in regular lines, uninfluenced in their direction by the water courses, and are abrupt and steep in