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mate. This substance, called whalebone, which thus supplies the place of teeth, consists of a peculiar kind of horn. Its plates differ in their length and strength, in different parts of the mouth, but the outer row of plates are by far the strongest and the longest, especially those which are midway between the throat and the snout. Internally, supposing ourselves to be placed beneath the roof, and regarding it from below, from the lower edges of the outer plates, (those which they inclose becoming shorter and shorter, as their origin is more internal, or nearer the centre of the roof,) we see the lower edges of all uniting to form one inclining plane, extending obliquely upwards to the roof. And, as the fibres of every plate are loose and separate at its inferior edge, forming a deep pendent fringe, by the gradual splitting away of its substance in proportion as it is used, we perceive the entire vaulted sides of the roof of the mouth to be, in fact, by these means, deeply lined with a clothing of thick and coarse hair, whence the ancients gave to this species of whale the name of Mysticetus.

Now, beneath this vault of hair, lies the enormous tongue of the whale, and exterior to it, is the immensely high lower lip, which, when the jaws are closed, shuts up over all externally to the very origin of the whalebone above, so as to entirely conceal it from view. By means also of this formation of the lip, and the circumstance of the upper jaw shutting into a cartilaginous groove at the extremity of the lower one, the most perfect valve is formed, which any pressure from without, only tends to render more secure from the ingress of the water.

The fringe, which I before mentioned, produced by the whalebone, (as it is constantly and gradually extending itself in length, by the growth of the whalebone behind it, in proportion. as it is worn away,) is thus always in a proper state of adaptation to the marvellous economy of the creature; for the most curious part of this beautiful mechanism is the net or sieve which it thus forms; an instrument which has been granted to this largest of creatures, for the purpose of straining or separating its minute prey from the body of water necessarily taken into the mouth with it, in feeding. For, in this whale, the mouth is of such enormous proportions, as to receive at once, even tons of water, and yet of such wonderful per

fection is its filtering mechanism through these hair-like filaments, that it rarely allows the escape of the nourishing particles diffused therein, although they be no larger than peas; its food consisting chiefly of small medusæ, crustacea, and zoophytes.

(To be continued.)

On the Inland Navigation of the United States of America.

PART II.

[Communicated by the Author. Continued from the Number for
January, 1828, Art. 1.]

THE success that attended the execution of the Western Canal of the state of New York, drew the attention of the inhabitants of Philadelphia and Baltimore to the subject of Inland Navigation. It was soon perceived that the trade of both these cities was affected by the diversion of a considerable part of the traffic of the country west of the mountains, to that new and more convenient channel. Each of these cities, therefore, entered eagerly into the search for channels equally advantageous; but these investigations have not been attended with any consequences of important value.

From Philadelphia three several routes have been examined; in one of these the summit is impracticable for want of a supply of water; the others involve an expense far beyond any probable return, in consequence of the number of locks that would be required to surmount the ridges. Hence it may be asserted that there is little probability of the opening of an entire canal from this city to the Ohio, or Lake Erie, although there is a strong probability that a mixed system of canals and railways will be successful. To this the legislature of the state have very recently directed their attention, and have made large appropriations for it. Two navigations, that will form important parts of such a system, have actually been completed.

Philadelphia lies between two rivers, the Delaware and the Schuylkill, which approach at that point to a distance less than two miles. The former is navigable for the largest ships, the latter for vessels of 100 tons. Immediately above the city the Schuylkill is interrupted by falls, and although from its volume

of water it would rank in a high place among European rivers, the nature of the country is such, that interruptions of a similar character are frequent throughout its whole course. As many parts of the river are bold and deep, the Schuylkill navigation has been effected by using the bed in such places, and connecting them by canals and lateral cuts. To deepen the river and check its current, twenty-eight wears have been thrown across it. The whole navigation amounts to 108 miles, 46 of which lie in the ancient bed of the river, and the remaining 62 in the artificial channels. Besides 28 guard-locks at the wears, there are 92 locks overcoming a fall of 588 feet. So that this comparatively short navigation has a greater change of level than the Erie canal of the state of New York. The grand object of this navigation was to form a water communication with a vast coal field, of which we shall have occasion to speak hereafter.

At a distance of 58 miles from Philadelphia (measured on the Schuylkill navigation,) is situated the borough of Reading. From this a canal, called the Union, has been completed to the Susquehannah river. It is 71 miles in length. The summit level is 300 feet above the Schuylkill, and 210 feet above the Susquehannah. In the plan of the canal a difficulty was found in obtaining a supply of water for the summit level. This has been obviated by raising the waters of the Swatura by machinery, at such seasons as the other sources are usually scanty, and this will no doubt be effectual.

An important improvement in the structure of the locks of this canal was planned and carried into effect, by the very intelligent and skilful engineer (Mr. C. White) who superintended its construction. This improvement consists in the suppression of the breast wall, and making the upper gate nearly of the same depth as the lower one. The bottom of the lock has a slight slope, and the upper reach of the canal is gradually deepened until its bottom reaches the same level as that of the lower. As the breast wall is the weakest part of a lock, and adds considerably to the expense of construction, while it involves, in addition, the cost and inconvenience of lateral culverts in the walls, this improvement may be considered as very important; it is, in truth, the only change of

real value that has been introduced into the structure of locks, since the time of the opening of the canal of Languedoc. We have seen a proposal for a similar change in the form of locks, made by a French engineer; and although he is, doubtless, no plagiarist, still it is proper to state that Mr. White's locks were not only planned, but built and in actual use before the French publication made its appearance.

The Susquehannah, we have stated, in the former paper on this subject, to be full of rapids and other obstructions, from the time it enters the state of Pennsylvania. It is practicable as a descending navigation for arks in times of floods, and an attempt was made, some years since, to mount against its current by means of a steam-boat. Although this vessel did mount the river, it appears doubtful whether the experiment will be followed by any useful results; for it would be impossible to convey in this manner any heavy lading.

There is, however, little doubt that a canal might be made in the valley of the Susquehannah, as far as its junction with the Tioga branch. The latter, running altogether on the western side of the great ridges of mountains, might readily be rendered navigable; and plans have been proposed, to connect it with the Gennesse River, and with the Seneca Lake, in the state of New York; by either of these, it would come into communication with the Erie canal, and thus with the lake of that name.

We consider this to be the best route by which Philadelphia can be brought by canals into competition with New York for the trade of the western country, unless some successful substitute be found for locks in inland navigation. It is, however, far more circuitous and distant than the New York route, but it has the important advantage, at certain seasons, of being earlier clear of ice, and closing later than the New York canals. It is probable, that some means may be found of lessening the distance, and for this purpose a canal route has been examined directly from Philadelphia to Harrisburgh, on the Susquehannah.

The legislature of Pennsylvania has recently adopted a great and general system of internal improvement by canals and rail-ways; and is thus the second state of the union that has

followed the example of New York, in appropriating its revenues and credit to great public works. The debt contracted for such objects stands upon a very different footing from that which arises from warlike enterprises. While the latter impoverish a country, and diminish the means of liquidating the expenditure to which they give rise, the former increase and extend the sources of wealth, and provide ample means for the repayment of the cost of their construction.

The chance of the city of Baltimore being able to effect an advantageous and direct line of water communication with the states west of the mountains, is less than Philadelphia. It is, however, better situated to avail itself of the descending trade of the Susquehannah, or of any improvements made in the bed, or the valley of that river. Failing in the hopes of a canal, a plan for a rail-way from Baltimore to the Ohio River has been set on foot; the enterprise has been taken up by a company, chartered by the several states through which it is to pass, and the whole of the stock subscribed. It yet remains, however, to be ascertained by experience, whether a rail-way can ever be made to compete on equal terms with a canal navigation.

The states of Maryland and Virginia have earnestly sought a mode of communication with the Ohio, and by its branch, the Allegany, with Lake Erie, through the valley of the Potomac. In this the general government has also taken an interest, and a route has been carefully surveyed by officers of the United States Corps of Engineers. This investigation has shown that a summit level can only be obtained, by deep excavation, or by a tunnel of nearly six miles in length, and that this summit will be elevated 2486 feet above the tide water of the Potomac, and 1730 above the Ohio at Pittsburgh. We therefore consider ourselves warranted in saying, that although certainly practicable, it will, if locks be used upon it, involve an expense far beyond any that can be reimbursed by its. revenue, or even by its public advantage. Notwithstanding this, a bill, authorizing a subscription to a company formed for making this canal, has passed the house of representatives, and will probably become a law. Within the state of Virginia, the sources of James River, which empties itself into the

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