It has already been stated that the very first attempt at "stirring up the bottom" successfully created a channel on the Southwest Bar 300 feet wide and 18 feet deep, for the sum of $75,000. Subsequently, (1858,) Messrs. Craig & Rightor having failed in their efforts at jettyconstruction, succeeded, by means of "stirring up the bottom with harrows and scrapers, dredging with buckets in some places," &c., "in making two channels 18 feet deep, and as long as the process of stirring up the bottom was continued by them, the channels preserved the requisite depth." (Phys. and Hyds. of the Miss., p. 455.) Subsequently (1859) the Department took the work in hand, still using the plan of stirring up the bottom by "dragging harrows and scrapers" over it. "The plan proved to be successful, and a depth of 18 feet was maintained upon the bar for the period of one year, at a cost of $60,000."

Thus we see that the very earliest attempt, by improvised methods, at scratching the surface of the bar with harrows, &c., produced, for $75,000, an 18-foot channel; that the process was repeated in 1858 with the same success, and two 18-foot channels obtained; and finally, the thing was again done under the immediate direction of the Department, and for the small sum of $60,000 a depth of 18 feet was maintained for a period of one year.

In face of these facts; in the face of the positive, formal, and official statement of the engineer in charge "that, so far as regards obtaining a 20-foot channel, the natural obstacles have been overcome, (reiterated under different forms,) and in face of the fact that since the proved success of stirring up by scraping with harrows, &c., for $60,000 a year, machinery expressly designed to this end has been invented and im proved upon, under the eye of engineer officers, to be operated at an expense of two hundred thousand dollars per annum, the majority of the Board advise you that "the results, so far, do not warrant the board in estimating a greater depth than 18 feet, at extreme low water, as capable of being maintained at the passes by means of the stirring-up process;" and, furthermore, that "this is inadequate to the requirements of the naval, military, and commercial services."

By reference to the best authority I have proved the adequacy of dredging operations on the bar by well-tested means; but I think there is yet room for improvement, and especially in diminishing cost. The utilization of the power of the current may perhaps be yet further effected, while the attainment of 20 feet depth on the bar has by no means been established to be the maximum. As to that depth, however, we have the strongest assurances.

With 20 feet at extreme low-tide, vessels drawing 223 feet could, owing to the softness of the bar, frequent the port of New Orleans, and

*The engineer, Captain Howell, of course, could not concur in our opinion in so direct conflict with his official statements. In his paragraph of dissent he avows himself to be "the only engineer, so far as he knows," who believes his own assertion that the "natural obstacles to obtaining a 20-foot channel across the bar of the Southwest Pass have been overcome," or who is so "sanguine" as to believe that with the two powerful and especially-designed dredge-boats, and $150,000 per annum, he can accomplish more than has been accomplished by others without such machinery, and for $60,000. But he certainly knew my opinion; not a singular one, I imagine, or one for which it would be of importance to cite names.

A simple design was made by one of the members of the board of 1852, (Major Beanregard,) and again brought to the attention of the general board. Its trial was urgently recommended by all the members of the first-named board, and by other competent judges.

Average high-tide is about 14 feet above "extreme" low-tide. foot more than depth on bar can (though with some difficulty) pass. of a lock a clearance of 1 foot is stated to me by one of our naval necessary for vessels of heavy tonnage and large draught.

Vessels drawing a On the miter-sills constructors to be

for mere commercial purposes probably 20 feet draught would be adequate. A draught of 23 feet will include 85 per cent. of the shipping of the world; and with a draught of but 18 feet vessels (steamers) can be built of 5,000 tons, carrying 70,000 bushels of corn, or about 11,000 bales of cotton.* It is clear, then, that, for commercial purposes, a depth of 20 feet on the bars of the passes will suffice to furnish a navigable outlet, and relieve the commerce of the valley from enhanced charges arising from insufficient tonnage in the transports.

The engineer has, in language already quoted, very forcibly described the impetus given to commerce through the passes by the successful dredging operations of the last two or three years; but the benefit, he says, is qualified partly by the doubt whether the process will meet the "future demands for vessels of deeper draught," but still more by doubt as to the uninterrupted annual appropriations by Congress; and hence the real obstacle to that confidence which will justify business men in investing their money in lines of steamships of magnitude such as will bring the cereals and cotton of the valley through this route, appears to be uncertainty as to the annual appropriations by Congress.

The remedy for this is clearly pointed out in the "Physics and Hydraulics of the Mississippi," in the very last paragraph of that work, (p. 456,) viz, "that a permanent fund be provided, untrammeled by restriction as to the mode of the expenditure, from which a sufficient sum annually can be relied upon for the continuous prosecution of the work," &c.

Congress has power, I presume, to provide such fund, or to make appropriations applicable for future years. But if absolute freedom of use be not claimed for the canal, if tolls enough merely for maintenance be imposed, then with equal propriety an amount no greater (for no greater is needed) may be raised from vessels passing the deepened bars.

An objection to a reliance upon the dredging process is urged that it could not be maintained during a period of war with a powerful maritime enemy. This objection implies a state of continuous blockade at the mouth of the river, and a protracted war. Protracted wars between powerful nations are no longer probable; they are ceasing to be possible; while the supposition of continuous blockade to one of our greatest seaports would be repelled, and indeed would be more destructive of the commercial use of the river-mouths than the usual bar obstruction.

The objection is not therefore in the same category with the demand for the defense of the works of an artificial canal, and it is not an overruling one. Still an improvement of one or more of the natural mouths by which a sufficient depth should be afforded without the continuous use of machinery, and which would not be subject to the objection just cited, would be desirable.

In turning to the subject of jetties, I do not know how I can better define at the outset my position in relation to them than by quoting from the draught of a report which has been submitted to the board, and which has already passed through your hands:

I can only reason on probabilities deduced from study of the river and the lights of experience; and so long as to establish the negative there has been, I need not say, no trial of the system, but not even a survey accompanied with a careful study and experiments, directed expressly to develop the cost and character of the work needed, I feel that I am justified in recommending it as probably furnishing the most speedy attainment of a deep-water channel, and one which will have some features of permanence.

See prospectus of Atlantic, Great Western and Southern Steamship Company. The proposed vessels draw but 18 feet.

In a passage already quoted from the report of the board of 1852, the rationale of the jetty system is explained. I further cite from the "Physics and Hydraulics of the Mississippi" the following:

The development of the laws which govern the formation of the bars has removed all uncertainty as to the principles which should guide an attempt to deepen the channel over them. The erosive or excavating power of the current must be increased relatively to the depositing action. This may be done either by increasing the absolute velocity of the current over the bar or by artificially aiding its action. To the first class of works belong jetties and the closure of lateral outlets; to the latter stirring up the bottom by suitable machinery, blasting, dragging the material seaward, and dredging by buckets. These plans are all correct in theory, and the selection from them should be governed by economical considerations.

Such is the theory, and no engineer has yet expressed a doubt as to the fact that concentration of the waters of one of the passes by jetties carried out to deep water would excavate the required deep channel. The difficulty and the cost of construction, the alleged necessity of costly annual extension, furnish the arguments why this method should not be resorted to. While the general laws which govern the formation of bars at river-mouths are universal, there are peculiarities in the formation due to the natural differences of character of the rivers and of the sea-shore where the mouth is situated. If the shore be itself sand or gravel, and not rock, a bar always forms, whether the river brings down sediment or not. The latter material cannot, therefore, be regarded as in any sense the cause of the bar, though when it exists it is found to be the material of which the bar is composed. The most intractable bars are usually found to be of the former class; and yet, with few exceptions, every harbor on our northern lakes constituted by a river or creek mouth has been improved by the construction of parallel jetties. That those jetties need sometimes to be prolonged is no denial of their efficacy.

In the thirteenth volume of the professional papers of the Royal Engineers, four different instances of the application of jetties are described: two, the Danube and the Oder, (the first a sediment, the second a non-sediment, bearing river,) successfully; another, the Vistula, (sediment-bearing,) unsuccessfully; and the fourth, the Rhone, of which it is stated: "They cannot be said to have failed, (for they were never fairly tried,) though their failure there would constitute no argument against their employment elsewhere."

Concerning the Vistula it is stated, "no more unfavorable circumstances for the opening of the river could be imagined" than those that existed at the old mouth, where, for one hundred and fifty years, jetties (always used, however) failed to produce an adequate permanent depth. In 1840 the river burst through a narrow tongue of land and formed a new mouth, five miles from the old one, to which "piers" (jetties) were immediately applied, by the effect of which, aided by dredging, a depth of 17 feet is obtained. Jetties were not, therefore, total failures, after all. At the mouth of the Adour, below Bayonne, (not cited in the volume referred to,) piers were carried out one and a half miles long in nearly parallel lines and with a narrow channel. The bar here was shingle, (i. e., gravel or pebbles,) and the operation is described (Minutes Institution Civil Engineers, 1861-'62) as "a total failure.”*

*

66

The conspicuous instance of the success of jetties is that at the Danube

Nevertheless the depth is said to have been increased; but inside, at a distance of half a mile from the original bar, an interior bar was formed, due probably to the seawaves' action on the shingle.

mouth. Here, as in the case of our own great river, a great sedimentbearing river discharges into a (nearly) tideless sea:

*

The base of the triangle which constitutes the delta forms upon the general outline of the coasts of the Black Sea a strongly-pronounced salient, which is connected with the primitive shore-line by curved contours. A complete analogy is thus found between the form of this delta and those of the other great rivers, the Nile, Ganges, and Mississippi. (Annales des Pontes et Chassées, Nov., 1872.)

Nevertheless, compared with the Mississippi delta, there are very strongly-marked differences:

There were at the Danube delta two natural actions going on. Opposite to each of the mouths of the river there was an accumulation; between the mouths there was an erosion of the shore. If the river had not been there it was natural to suppose that the whole of the shore would have been eaten away uniformly; and therefore the amount of solid matter brought down by the river was not to be measured by the apparent width of the extension opposite to the mouths, but by the width of that extension added to the width of the recession in the parts between the mouths. This tendency to erosion from causes independent of the river was another circumstance conducive to success. (Minutes of Proceedings of Institution of Civil Engineers, vol. xxxvi, p. 231.)

And, again, the formation (at the Sulina mouth, at least) exhibits firmness and (sometimes) even hardness. The village of Sulina, at the very mouth, is, in part at least, of stone buildings, on the natural soil. The bar sometimes, and especially during times of floods of the upland rivers, (the first effect of high floods having been with the unimproved bar to deepen it, the second to reform it further out, and of harder materials,†) being incrusted with hard sand, which yields with difficulty to the plowing action of a vessel's keel, and the lateral shoals on which the jetties were laid being sufficiently firm to support the "riprap" construction without materially yielding.

Another point of alleged difference, very much insisted upon by many, is the littoral current off the Danube mouths. Colonel Stokes, R. E., (British commissioner,) states:

Its existence was ascertained before the works were carried out, the author having instituted a series of observations with floats to test the amount of the current, the result of which proved that there was a decided current across the mouth of the river, which extended as low as 4 feet below the surface in a depth of 10 feet. The depth on the bar at that time was 8 or 9 feet. It was also shown that during calms, northerly and northwesterly winds, there was a considerable littoral current from north to south, and during southerly and southwesterly winds, a surface current from south to north; but it was so feeble as to indicate that the force of the wind had but just overcome that of the current from north to south. In strong westerly winds there was a countercurrent setting in about 5 feet or 6 feet below the surface; but this was not observed during the northerly winds, which so generally prevailed at the mouth. The Kilia branch, fifteen miles north of the Sulina, discharged two-thirds of the water of the Danube into the Black Sea, the whole of which set past the mouth of the Sulina.

Seamen found a very constant current of from one-half knot to one knot per hour, setting from the north to the south along the coast of the delta. Colonel Stokes therefore thought it established that there was a littoral current generally from north to south across the Sulina mouth. (Minutes of Proceedings of Institution of Civil Engineers, vol. xxxvi, p. 247.)

To the undersigned Sir Charles Hartley stated that the current averaged about half a mile, confirming also the fact of its occasional fluctuation.

Again it is to be observed that while each particular pass (and even each small "bayou") of the Mississippi delta thrusts out, in its own particular finger-like promontory, the Sulina mouth is not thus thrust out, but is on the general line of the shore.

*The ratio of solid to fluid in the Danube waters is by volume 2; nearly the same as for the Mississippi.

+ The usual depth was about 9 feet, varying, however, from 7 to 11 feet.

The Danube divides at about fifty miles from the coast into the Kilia and Toultcha branches, of which the former conveys two-thirds (about) of the entire discharge. The latter and more southern branch again divides into the St. George's and Sulina arms; the latter running eastward nearly. The St. George conveys nearly one-third, leaving to the Sulina but two-twenty-sevenths. The mouths of the Kilia and St. George are about forty miles separated, the Sulina mouth nearly midway between them, the trend of the coast-line being north and south. Finally it may be said, the discharges of the St. George and the Southwest Pass of the Mississippi have the same ratios, one-third of the total discharge, and the Sulina the same ratio as the South Pass, (73 to 8 per cent.) Hence, the total discharge of the Mississippi being more than three times that of the Danube, the Southwest Pass discharges three times as much as the St. George, and the South Pass three times as much as the Sulina. The current-velocities are, if anything, somewhat greater in the Danube than in the Mississippi, the inclination of surface in the Sulina 3 inches per mile during floods, and about 1 inch per mile at low-water.

The sea-depths at three miles from land are 16 fathoms off the St. George, and only 10 fathoms off the Kilia and Sulina.

On the other hand, at 1,000 feet outside the bar of the Southwest Pass, the Gulf is about 22 feet deep; at 4,700 feet, 100 feet deep; at 43,000 feet (eight miles) 300 feet deep; and eleven miles, 900 feet deep, 150 fathoms. (Physics and Hydraulics of the Mississippi, p. 444.)

The Kilia, though the greater arm, was deemed ineligible in consequence of its subdivision into numerous small delta-arms of its own. To the St. George, possessing a good navigable channel with 16 feet of water, (while that of the Sulina, with but 13 feet, was very bad,) was given the preference.

When the engineer presented his plans to the European commission it had three other designs before it "from eminent technical authorities" who had visited the ground:

In one respect alone all were agreed, and that was in recommending that whichever mouth were chosen, the system of improvement should be that of guiding the riverwaters across the bar, by means of piers projected from the most advanced dry angles of the mouth; or, in other words, that of concentrating the strength of the river-current, on the bottom of the proposed improved seaward channel, by an artificial prolongation of the river-banks into deep water.-(Minutes of Proceedings of Institution of Civil Engineers, vol. xxi, p. 284.)

The English, French, Prussian, and Sardinian governments then referred the whole subject to the decision of two military and two civil engineers. These gentlemen, in an elaborate report, unanimously condemned the jetty system, and "recommended the choice of the St. George branch with a sea-entry and gates," (in other words, a "shipcanal," "independent of the mouth; a project diametrically opposed in principle to the system of improvement previously proposed by all the naval and engineering authorities, who had visited the several mouths of the Danube, and had studied their peculiarities on the spot." (Ibid.) The final result of these complications, and of the impatience of the merchants for some immediate relief, was that the commission, under advice of its engineer, "resolved to improve the channel across the bar of the Sulina branch, by means of guiding-piers of a temporary character, but carried out in the lines which the author had designed for permanent works."

It is not in place to go into particulars concerning the progress of a work protracted through many years through inadequacy of funds.