Naturally, the highest intermediate summit be tween the Atlantic Ocean and German Sea was only about 70 feet in this interesting valley.
The North American Glen, on a much larger scale than that of Scotland, has the southern ex treme in the outlet of the Hudson into the Atlantic Ocean, between Staten and Long Islands, and its northern termination in the St. Lawrence, at the mouth of Richelieu, or, as called in the lower part of its course, Chambly river. The tide part of the Hudson, about 160 miles in length, though usually denominated a river, is really a bay, in the strict meaning of the latter term. This bay is merely long and narrow, and in those circumstances only does it differ from other bays. Rivers and bays differ materially in the opposing curves of their sides respectively. Rivers have opposing sides, with usually very nearly coinciding curves; on the contrary, bays have entering and retiring curves, with no apparent compliance in their inflections. Under the preceding distinction, the Hudson, be low the junction of Mohawk and Hudson proper, is a bay.
Immediately below Glenn's Falls, the Hudson, as stated above, enters the Great Vale, and abruptly turns to the southward, and, continuing that course 35 miles, unites with the Mohawk a very little above the head of the titles. The intermediate distance of 20 miles from the great bend of Hudson, below Glenn's Falls, to the head of Lake Champlain, at the mouth of Paulet river, contains the highest summit level, 140 feet oceanic elevation between the tides of St. Lawrence and Hudson. The mind of the voyager on Lake Champlain, in view of massy mountain scenery, can scarcely admit the proof afforded by mathematical admeasurement to convince him that the fine sheet of water on which he is sailing is really only 87k feet above the level of the Atlantic Ocean, and that so small a compara tive descent would bring him to the tide level in St. Lawrence.
The whole length of the Great Glen of North America is within a trifling fraction of 375 miles in length, extending from north latitude 34' to 2', and differing so little from the meridian as not to deflect one degree of longitude in 328 min utes of latitude. But what in a very striking man ner gives interest to both the American and Scot tish glens, is the little deviation of either from a straight line between the extremes. The IIudson bay and river, Lake Champlain and Richelieu river, forming the chain of the American Glen, as do Loch Linnhe, Loch Eil, Loch Lochi, Loch Oich, Loch Ness, and Murray Frith, that of Scotland.—
But to return to our survey.
The fall in the Hudson waters, from Glenn's Falls to tide water, is 104 feet, which has been overcome by locks on the Hudson and Champlain Canal.
Mohawk river, or the northwestern constituent of the Hudson, has its remote sources interlocking with those of Black river and Oswego, flowing into Lake Ontario, and those of the Chenango branch of Susquehannah. The Mohawk valley lies very nearly at right angles to that of Hudson, and pre senting the second lowest gorge in the Appalachian system between the Atlantic Ocean and Canadian inland sea. The higher sources of Mohawk flow, by a very rapid descent, to the southward about 20 miles, to an alluvial summit level of only 421 feet above tide water in Hudson Bay; the Mohawk sum mit level being 281 feet higher that of the Hudson and Champlain.
In a state of nature, previous to the construction of the great western canal, in seasons of high floods, the waters were so nearly poised on the level near where Rome now stands, that part of the flow passed into Lake Oneida, by Wood creek, and thence into Lake Ontario, by Oswego river. The discovery of this remarkable feature in the topography of the table land between the Mohawk and Oneida valleys was one of the incidents which led, and naturally lead, to the original design of the Hudson and Erie canals; and the existence of such a depression in the table land between the tide, deep, and narrow val ley or bay of Hudson and the middle part of the St. Lawrence basin, afforded an opening to inland navi gation very rarely found in the mountain systems of the earth. It may also be remarked, that this plateau or table land is alluvial, and that in the construction of the Hudson and Erie canal, the most extensive masses of rock encountered were found below the summit level; and that feature in the lo cal line of the great canal of New York leads on to the remark, that the mountain chains which com pose that section of the Appalachian system, south west from the Hudson, do not ever generally, much less uniformly, constitute the dividing ridges be tween the sources of the rivers of the Atlantic slope and those which flow into the Mississippi basin. This relative structure of our mountains, and the courses of our rivers, so contrary to common opi nion, demands and deserves particular notice and description, since without understanding this per haps peculiar structure, no adequate idea can be obtained of the true configuration of the United States.