receives Savage river from the north, and inflecting to the south of east, in a distance of 10 miles, traverses one or two minor chains, and resuming a north-eastern course of 18 miles receives Wills creek at the town of Cumberland. The Potomac fed by mountain torrents, has at the influx of Wills creek become a river of considerable volume, and again breaking through two mountain chains in rapid succession, through which the channel is so tortuous, that in one place the course is turned backwards to south-west, but quickly winding round to a course of a few degrees south of east, unites with the South Branch by comparative courses, 15 miles below Cumberland.

What is called the South Branch, is the real and main Potomac, having its remote source in Pendleton county, Virginia, as far south as Lat. 38° 32'. The numerous mountain streams which, by their final union form the South Branch, originate in the mountain vallies, between the Kittatinny and Alleghany chains, and from thence by a general course of north-east, they unite near Morefield, in Hardy county, and also near the intersection of N. Lat. 39° and 2o W. Lon. from W.C. Below the union of its principal constituents, the South Branch, with out receiving much additional water, continues its north-eastern course over Hardy and Hampshire counties, 40 miles to its union with Potomac. The enlarged volume formed by both streams, traverses a mountain chain immediately below their junction, and again winding round to a course of north-east, continues that direction by a very crooked channel, but comparative distance of 25 miles, to Hancocks town in Washington county, Maryland, having received several creeks from the north, and beside some others of less consequence, Great Cacapon from the south. At Hancockstown the channel of Potomac has reached its extreme northern point, N. Lat. 39° 41' nearly, and less than two direct miles from the southern boundary of Pennsylvania; but again inflecting to a course of S.S.E. 20 miles to the influx of Conecocheague, from the north, having traversed the Kittatinny and entered the fine valley between that chain and the Blue Ridge. Below the mouth of Conecocheague, the course is west of south 5 or 6 miles to the influx of Opequan river from Frederick, Berkeley and Jefferson counties, Virginia, but having received the latter stream, the Potomac bends to a general course of S.S. E., 20 miles to its junction with the Shenandoah, and passes through the Blue Ridge at Harper's Ferry.

The real length of the channel of Potomac will be shown partially in the subjoined tables, but it may be observed here, that in order to preserve consistency between the actual area drained, and the channel, only the general length can be expressed in the verbal description.

Shenandoah brings to the Potomac little less volume than the main stream above their union. The former rises in the Kittatinny valley, as far south as 37° 55', and in the southern angle of Augusta county, Virginia, two degrees W. of the meridian of W. C., interlocking sources with the North, or Great Calf Pasture Branch of James river, and

on the opposite side of Blue Ridge from the sources of Rivanna. The entire valley of Shenandoah is comprised within and forms a part of the great Kittatinny valley. The main stream is formed by two branches, which, taken together, drain the far greater part of Augusta, all Rockingham and Shenandoah counties, and finally unite on the southern border of Frederick; the main or south-eastern branch having flown at their point of union, by comparative courses, to the N.E. 85 miles. Gradually inclining upon the base of Blue Ridge, the Shenandoah below the union of its two constituents continues north-eastwardly 35 miles to its junction with the Potomac, at Harper's Ferry, after an entire comparative course of 120 miles.

The entire upper valley of Potomac stretches along the Blue Ridge, from south-west to northeast, 160 miles from the sources of the Shenandoah to those of Conecocheague. It is 75 miles where broadest, between the Alleghany at the source of Potomac to the Blue Ridge, opposite the sources of Hedgman river; but the mean width is only about 50 miles; area 8000 square miles.

By reference to the tables of relative height, it will be seen, that the low water level in the river, at its passage through Blue Ridge, is 288 feet above the level of tide water in Potomac. The lowest elevation that can be given to any part of the arable soil of Upper Potomac valley, is at least 350 feet, or a full equivalent to a degree of latitude, as regards mean temperature. Under the head of the Appalachian chains, the rapid rise of their respective vallies were shown, and we may, to save reference, observe here, that the valley of the South Branch, and which is continued northwardly across the valley of Juniata, and southwardly in the higher valley of James river, has its lowest point of depression between Susquehannah and New river at Cumberland, where the common water level is 578 feet above the Chesapeake tides. We may therefore safely assume 600 feet as the lowest arable surface of the South Branch of Potomac. Where the Ohio and Chesapeake canal is to pass the Alleghany mountain, between the sources of Little Will creek and Casselman river, or the extreme eastern branch of Youghiogany river, the summit level is 1903 feet by actual admeasurement. The extreme highest peaks or ridges of Alleghany exceed 2800 feet; and we are safe in stating a difference of 1200 feet between arable land of the lowest part of the Upper Potomac valley, and the most elevated farms along the higher mountain vallies; and as many of these farms are actually on mountain table lands, the rapid change of temperature experienced in a few miles is fully accounted for from relative height.

Passing the Blue Ridge the Potomac flows 15 miles S. E. by E. to the influx of Monocacy, and passage of the main stream through the South East Mountain. At this latter pass the water level is still 224 feet above tide water; and similar to its inflections below Cumberland, and below its passage through the Kittatinny, the Potomac bends 5 or 6 miles to the south-westward, after passing South East Mountain, and thence very gradually

curves to a course of S. E. which it maintains 30 miles to its final descent over the outer primitive ledge, into tide water at Georgetown. Below the head of tide water in Potomac, occurs one of those river resemblances which demonstrate the extent of mountain influence. Like the Delaware below Trenton, and the Upper Chesapeake below the influx of Susquehannah, the Potomac, after meeting the tide, first inflects along the base of the primitive ledge, by a course south of west upwards of 20 miles, and thence, by a very extensive curve, regains a south-eastern direction. It is in the above noted great curve that the Potomac so nearly approaches to the Rappahannoc, as we have shown under the head of the latter river.

From its leaving Blue Ridge to where it finally quits the primitive ledge, between Charles county in Maryland, and Stafford in Virginia, the Potomac receives from the left Cotoctin, Monocacy, Seneca, Rock, East Branch, Piscataway, and Mattawoman; and from the right, Goose creek and Occoquan, with many of lesser note from each shore.

The Monocacy valley is a part of that between Blue Ridge and South East Mountain, the main or middle stream flowing, a little south of west, along the mountain valley, having interlocking sources with those of Conewago and Codorus branches of Susquehannah, comprising the far greater part of Frederick county, in Maryland, and the southern part of Adams, in Pennsylvania; length 50 miles, mean breadth 20, and area 1000 square miles.

Below the influx of Monocacy, no stream above the size of a large creek enters Potomac from Maryland. Rock creek, entering between Washington and Georgetown, and the North East Branch, both rise near Mechanicsville, in Montgomery county, and within twenty miles from the city. The latter opens to the width of a river, and forms the harbour at the United States navy yard, and gains importance from this circumstance; but its extreme head is not quite as far remote from their common recipient as is that of Rock creek. Indeed, from the source of the Patuxent, in South East Mountain, to its outlet into Chesapeake, the distance between its channel and that of Potomac in few places amounts to twenty miles, and does not average fifteen. On the opposite side to the vallies of Moncacy, Rock creek, and North East Branch, there is a small section of Virginia drained into Potomac. This section, embracing the northern part of Fauquier, and all Loudon, Fairfax, and King William counties, is watered by Goose creek, Occoquan, and some smaller streams. But, as noticed under the head of Rappahannoc, the valley of Potomac becomes restricted to a narrow slip below tide water in the former. The whole of that part of the basin of Potomac below the Blue Ridge, from the source of Monocacy to Smith's Point, on the right side of the mouth of Potomac river, is in length 165 miles; the mean breadth 30; and area 4950 square miles.

Combining the two sections above and below the Blue Ridge, the whole basin of Potomac extends over an area of 12,950, say 13,000 square miles. VOL. XVIII.-PART I.

Extending in Lat. from 37° 50' to 40° North, and in Lon. from 0° 45' E. to 2° 45′ W. from W.C. From its relative position, and from the great distance inland to which its channel admits ships of the heaviest draught, the basin of Potomac is a very interesting object in physical and political geography; and it is naturally, and by the erection of the Baltimore and Ohio Rail Road, already artificially connected with the western shore of Chesapeake Bay, between its own estuary and that of Susquehannah. In a direction very nearly from north to south, and from the southern boundary of Pennsylvania to the lower part of St Mary's county, Maryland, extends a strip of about 110 miles in length, and where broadest, in Harford and Baltimore counties, 45 miles wide. The mean width, however, about 25, area 2750 square miles. This slope is drained by Patuxent, Patapsco, and Gunpowder rivers.

The western shore of Chesapeake, broken into minor bays by the confluent rivers, is opposed by another slope still more indented. The eastern shore of Chesapeake is, in one respect, very remarkable; that circumstance is, that the confluent creeks and rivers rise almost on the margin of the Atlantic Ocean from Cape Henry to Indian river; and again, a similar remark, with some limitation, may be extended to that part lying between Chesapeake and Delaware bays, as, in the latter case, the comparatively large streams of Pocomoke, Nantikoke, Choptank, Chester, Sassafras, and Elk rivers, are opposed by a series of mere creeks, flowing across a strip of about one hundred miles in length, with a mean width of fifteen. The whole elliptic curve, from Cape Charles to the head of Elk river, following the shores of the Atlantic Ocean and Delaware Bay, in a distance of two hundred miles, does not exceed an average width of more than ten miles; area 2000 square miles.

The Chesapeake slope of the peninsula we are surveying is also very narrow, not exceeding a mean breadth of five miles for the first seventy miles from Cape Charles to the mouth of Pocomoke river, but thence rapidly widens in the basins of Pocomoke, Nantikoke, and Choptank rivers to a mean breadth of 50 miles, and length of 70 miles. Again, contracting over the basins of Chester and Elk rivers, to a point towards the source of the latter, the whole eastern slope of Chesapeake Bay presents an elongated ellipse of 200 miles from south to north, mean width 25, and area 5000 square miles; extending in Lat. from 37° 7' to 40° N., and in Lon. from 0° 40' to 1° 40' E. from W.C. The entire peninsula, by careful measurement, including the space between the head fountains of Elk river and Cape Charles, embraces a superficies within a trifling fraction of 7000 square miles; extreme breadth 65, but mean breadth 30, very nearly. From these elements, five-sevenths of the peninsula is drained into the Chesapeake Bay.

For specific description of the residue of the Chesapeake basin, see article SusSQUEHANNAH. The relative extent and elevations of the sections are shown by the subjoined tables. 2 U

The three Tables VIII., IX. and X., as far as the elements on which they are founded are correct, must be of great service in showing the intermediate elevations, between tide water in the Roanoke and James river, and also of the connecting ground between those rivers in the higher part of their respective vallies above Blue Ridge. It ought, however, to be carefully observed, that in all tables of elevations taken from measurements along the streams having canal operations in view, that the height at any given place must be below the arable surface; therefore, as applied to an estimation of aerial temperature, without allowance for greater height, the results would in every instance yield a too high temperature. The summit levels are also much below the mean height of the mountain chains, but they give, where the surveys have been carefully made, the lowest gaps or passes of the chains in the vicinity of the line of survey.

proceed to a review of the Delaware, Hudson, Canadian, and Ohio natural sections, before inserting the tables of elevation, which exist on the canal routes uniting Pennsylvania, New Jersey, New York, and Ohio. The canal routes themselves, also, can be much more conspicuously delineated when brought under one field of view.

Delaware basin, from physical position, and from the immense advance of human power on its surface, is a region of great importance in the geography and statistics of the United States. Taken in its fullest extent, Delaware basin has that of Susquehannah to the west and north-west; that of Hudson north and north-east; the eastern slope of New Jersey to the south-east, and opens, by a wide bay, to the Atlantic Ocean on the south. Its greatest length is very nearly, from north to south, 250 miles; and also deviating but slightly from the meridian, 2o East from W.C. In Lat. it extends from Cape Henlopen, 38° 43′ North, to the sources of the Coquago branch, 42° 30' North, and in Lon. from 0° 42' East to 2o 35' East. The greatest breadth is about ninety miles from the sources of Tulpehocken to those of Assanpink; but the mean width is fully estimated at 45 miles; area 11,250 square miles.

Without taking the extreme elevations of the Catsbergs, from which issues the Popachton branch of Delaware, we may, however, safely estimate the extremes of arable height on the Delaware basin at 1800 feet, or an equivalent to three degrees of latitude, and consequently, as the actual extremes of latitude is 34°, the extremes of temperature is 6o.

Delaware Proper is formed by two main confluents, Coquago and Popachton, both rising in the Catsbergs. The Coquago, or most remote, has interlocking sources with those of Susquehannah and Schoharie, and flowing south-west 55 miles, until within 8 miles from the channel of Susquehannah, where the two streams, approaching thus near, retreat from each other in opposite directions. The Delaware, rapidly inflecting to south-east, receives in that direction, at 12 miles, the Popachton, and preserving the latter course 50 miles, by comparative distances, but very winding channel, to the extreme northern angle of New Jersey and influx of Nevesink river.

The Popachton issues from the Catsbergs, and probably contains the highest fountains of the Delaware, flows south-west, very nearly, an equal distance with the Coquago, above the great bend of the latter; the two streams preserving a relative distance of from 8 to 10 miles asunder.

At the influx of Nevesink, the Delaware reaches, and is turned to south-west by the Kittatinny chain, down which it flows 35 miles, to the influx of Broadhead creek, and the passage of the stream through the Kittatinny chain at the pass called the Delaware Water Gap. Here this now large navigable stream assumes a course a little west of south obliquely over the Kittatinny valley, 20 miles, to the influx of the Lehigh, at the foot of the Blue Ridge.

The beautiful mountain stream, the Lehigh, is the lowest and largest of three considerable conflu

ents of the Delaware, which drain that part of the basin of the latter above Blue Ridge, and westward of the main stream.

Lackawaxen, become important from its mines of anthracite coal, and canals already constructed along its valley, draws its sources from the same mountain chain from which rises the Lackawannoc branch of Susquehannah, and, flowing south-eastward about 30 miles comparative distance, falls into the Delaware between Wayne and Pike counties. It is a very large stream when the volume is compared with the brevity in length. Broadhead creek is a much less important stream than the Lackawaxen, and flowing from the lower part of Pike and higher part of Northampton, enters Delaware river in the latter county, and immediately above the Water Gap.

The Lehigh heads with both the preceding streams, and with some of the south-eastern creeks of Lackawannoc. Its extreme western source is about five miles eastward from the channel of the Susquehannah at Wilkesbarre. The numerous confluent creeks rising on a table land of at least 1400 feet mean height, flow generally to the south-westward 20 miles; unite between Northampton and Luzerne counties, inflect to a course of a little east of south 25 miles, to the north-western foot of Blue Ridge. In the latter course, the channel of the Lehigh is tortuous, and falling upwards of 800 feet, or, if we allow 40 miles to the actual channel, 20 feet per mile. The stream is a series of small cataracts, but, what is truly remarkable, with no actual fall, in the true meaning of the latter term.

Passing the Blue Ridge, the Lehigh inflects to S.S.E. 18 miles, by comparative distance, to the influx of Little Lehigh and north-western foot of Blue Ridge, at Allentown. Turned to north-eastward by the Blue Ridge, the Lehigh flows down that chain 12 miles, to its union with the Delaware, at Easton. The arable soil, or the point on which the lower part of Easton stands, is about 200 feet above tide water, and the higher sources of Lehigh being at the least 1500 feet, gives a difference of arable height, to the extremes of its valley, of 1300 feet. In direct distance, it is only about 45 miles from the higher spring to the outlet of this mountain river. The prodigious masses of mineral coal found in the mountains of the Lehigh have enabled human genius and labour to render its precipitous current commercially available.

Traversing the Blue Ridge, and continuing to the southward 10 miles, having passed in the latter distance the South East Mountain, the Delaware turns to the south-eastward 35 miles, to its fall over the primitive ledge, and meeting the tides at Trenton. Similar to the head of Chesapeake Bay, or in fact the Susquehannah, as also the Potomac below Georgetown, James river below Richmond, and the Roanoke below Weldon, the Delaware bends along the shelf of the primitive ledge on its mingling with the tides. This phenomenon is, however, most conspicuous, and preserved to a greater distance in the Delaware than in either of the other rivers in which we have shown its existence.

Having become a tide water channel, the Dela

ware curves below Trenton gradually to the southwestward, and maintaining that course, by comparative distances, 60 miles, receives the Schuylkill from the north-west, at very nearly mid-distance.

Schuylkill river is the largest confluent of the Delaware, interlocking sources with those of the Lehigh, and also with those of the numerous confluents of the Susquehannah, from the Nescopec to the Conestoga inclusive; drawing its higher and principal sources from the rugged mountain valley above Kittatinny: it is, indeed, the same valley, or series of vallies, which gives source to the Lehigh. The upper Schuylkill drains a region of from 400 to 1200 feet, exclusive of the mountain ridges. Falling from this elevated tract, the higher branches unite above, and traverse the Kittatinny chain by the Schuylkill Water Gap, after a general course of 20 miles. After its passage through the Kittatinny, the stream assumes a course a little east of south, 18 miles, to the influx of Tulpehocken from the westward, and, traversing Blue Ridge at Reading, turns to the south-eastward, and flowing in that direction 45 miles, by comparative courses, to its passage over the primitive ledge, in the vicinity of Philadelphia; where, turning to the southward five miles, joins the Delaware, after an entire comparative course of ninety miles. The valley of Schuylkill lying between, and in a remarkable manner parallel to the contiguous parts of the basins of Susquehannah and Delaware, is a parallelogram of 80 by 22; area 1760 square miles.

From the head of tide water, the channel of the Delaware gradually widens, and assumes the features of a bay: at Philadelphia, it is about a mile wide, and continues from one to two miles in breadth until passing the great bend, near where it is now connected with the Chesapeake Bay by Chesapeake and Delaware canal; but here turning to south-east and rapidly widening into what is more particularly called Delaware Bay, a sheet of water 60 miles in length, and from two or three, to twenty miles in width. This expansive opening to the Delaware basin is terminated on the north-east by Cape May, and south-west by Cape Henlopen.

The numerous shoals and channels render the navigation of Delaware Bay intricate, but it admits the entrance of the largest vessels of war as high as Reedy Island, and merchant ships of large draught to Philadelphia: sloops and steam boats ascend to the lower falls at Trenton. The artificial navigation of the basin will be noticed in the sequel.

The Delaware channel is, with the exception of the higher Coquago, a political boundary. From where it reaches North Lat. 42°, above the mouth of Popachton, to the Kittatinny chain, it separates New York from Pennsylvania; from thence to 12 miles below the influx of Schuylkill, it forms the boundary between New Jersey and Pennsylvania; and finally, Delaware Bay has New Jersey to the northeast, and the state of Delaware south-west.

The head of tide water in Delaware and Raritan rivers are only 26 miles asunder, though the distance between their respective openings to the ocean is 120 miles. The intermediate space forming the south-eastern part of New Jersey, and, if the entire