I.-IMPROVEMENT OF THE MOUTH OF THE MISSISSIPPI RIVER AT SOUTHWEST PASS.

In my letter to the Chief of Engineers, dated April 19, 1870, I had the honor of recommending certain additions to the machinery of the dredge-boat employed on this work, and to advise that the work of making them be proceeded with at an early day in order to give time for completing them and testing their efficiency before the active commercial season at this port should set in, and render both continued and effective work on the bar of the first importance.

The additions proposed were designed to give to the excavating propeller of the dredge-boat increased efficiency as a dredging-machine by confining its action while at work to a limited area of the bar and by directing to the best advantage the resulting currents. They had for a further object the protection of the blades of the propeller from frequent damage.

On the 1st of July, 1870, the dredge-boat (Essayons) having suspended work on the bar at Pass à Loutre, was at the wharf in this city awaiting the repairs and additions recommended.

On July 5 a letter approving my project was received, and the work of carrying it out at once commenced.

Notwithstanding my close personal superintendence of this work, it was not completed until the 14th of October. My own illness and the outbreak of the yellow fever on board the dredge-boat, resulting in the loss of my able chief steam engineer, Mr. John F. Robinson, then prevented a test of the new machinery before the 31st of October.

On the latter date work on the bar at Southwest Pass was commenced and continued during 1st, 2d, and 3d of November. The time of actual work on the bar was twenty-eight and one-fourth hours. October 30, careful soundings over the bar showed a channel across, (a gulley made by dragging vessels over,) having through it at mean low tide a depth of but 16 feet for a length of about 1,400 yards. On the afternoon of November 3 there was available a channel about 50 feet wide at the narrowest point, and 19 feet deep, which shows an amount of deposit excavated during the four days' work approximating 22,400 cubic yards.

On November 4 there were five cases of yellow fever reported on board the dredge-boat, and I was obliged to suspend work to bring the sick to this city for medical treatment, and the vessel for disinfection. On November 19th work was recommenced at Southwest Pass. The following extracts from my monthly reports of progress show with what

success:

Report of December 6.

November 19.-Work on the bar at Southwest Pass was recommenced. Worked three three hours, and was stopped by bursting of a steam-valve.

November 23.-Worked four hours forty-five minutes.

November 24.-Bar too rough for work and vessels aground.

November 25.-Worked three hours forty-five minutes; ship blocking channel.

November 26.-Worked two hours; ship yet blocking channel.

November 27.-(Sunday;) no work.

November 28.-Worked six hours and forty-five minutes.

November 29 and 30.-Too stormy for work.

December 1.-Worked five hours and fifteen minutes.

December 2.-Worked six hours. On this date Captain J. W. Wilson, master of Essayons, reported, by telegraph: "Least depth of channel at mean low tide, 18 feet width between outer lumps, 112 feet; least width of channel above lumps, 132 feet.' December 3.-Worked seven hours and ten minutes; and the following list of sound

ings was reported. (tide of a foot below mean low tide :) From Wreck buoy to Cleopatra buoy 181, 171, 174, 18, 19, 184, 19, 19, 184, 18 feet. From Cleopatra buoy to outer lumps, 19, 19, 20, 20, 18, 17, 21, 20, 20, 19, 19, 184 feet.

Report of January 4, 1871.

Work with the Essayons at Southwest Pass was steadily continued during December.

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Several unimportant accidents occurred to the engines and dredging-machinery, necessitating repairs which were made on board ship, causing but slight delay in the work of dredging. Unusually stormy weather was experienced, causing considerable delay. Delay was also caused by general use of the channel worked by the Essayons. Perhaps much of this delay might have been avoided had I not instructed Captain Wilson to take no risks by working in rough weather or while vessels were crossing the bar. The rapidity with which work can be done, under favorable circumstances, makes it unnecessary for us to risk anything.

Captain Wilson reports, December 31, 4 p. m.: A channel 18 feet deep (least) and 154 feet wide, at mean low tide. This will accommodate the deepest-draught ships coming here. I propose to widen the channel to 200 feet, and then confine work to keeping it open during the winter and to further deepening it.

The river now is rising very slowly, and our work is done during the day-time on the incoming tides.

Report of January 31.

January 2, 3, 4 and 5.-A total of twenty-seven hours' dredging closed with the result stated in the following extract from report of Captain J. W. Wilson, viz: "On the afternoon of January 5, the channel opened by the Essayons at Southwest Pass was 183 feet in depth at a remarkably low tide, and 215 feet in width, full length of the bar. There are no lumps in the channel."

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It being necessary at this time to resupply the ship, she was ordered, with the barge in tow, to start for this city on the 6th. She arrived here on the 7th. Had it been considered necessary to do so, she could have returned to Southwest Pass on the 11th. I desired to keep her here for several reasons, stated as follows:

1st. We left as good a channel at Southwest Pass as could be desired.

2d. The river had been at a low stage (from 144 feet to 15 feet below high water of 1862 at New Orleans) for a long time, and I wished to ascertain how much filling would take place in the channel during a reasonable time, under the existing conditions, if not disturbed by dredging. Two weeks was the time set for the experiment, and a close watch was kept to see that commerce was not inconvenienced by allowing too much filling.

3d. In the mean time I could change ballast and stop leaks in sinking tanks, so that on recommencing work the vessels could be sunk for working to the greatest depth attainable.

4th. I could also have time for making general repairs to the coal-barge, such as have been heretofore reported desirable.

5th. I could economize in coal, which, owing to a temporary blockade at Louisville, had run up in cost to $18 per ton.

January 23.-Work on the bar was resumed. A careful examination showed that but slight change in depth and width of channel had been effected during the interval between the 5th and 23d. Five and one-sixth hours' work was done on the 23d. Six and a quarter hours on the 27th. Stormy weather prevented further work. My orders to Captain Wilson were to work only every other or every third day, if he found that by so doing he could maintain a good channel. The saving effected by this course would amount, on an average, to $100 per day not worked. On the 26th Captain Wilson reported: "Ships drawing 17 feet sail in, and vessels drawing 18 and 18 feet tow in without trouble."

Report of February 28. .

The Essayons was at work on the bar at Southwest Pass during the 1st, 2d and 3d— total time, 134 hours-leaving a channel 260 feet wide and 19 feet in depth at mean low tide. This work was done with but three blades in the excavating propeller, one having been previously broken on obstruction in east mud-lump.

On the 4th, while passing Stake Island, the excavating propeller struck a sunken wheel and shaft, (the presence of which was not before known,) and sustained very serious damage. One blade of the propeller was broken entirely off; the other two were partially broken off; the plow-handle was broken in two; the propeller-shaft

was badly bent; the shaft-casing and sleeves damaged so that they had to be replaced by others, and the propeller-hub slipped.

NOTE.-Repairs were at once commenced, and work on them continued during the

month.

During the delay there has been no complaint about obstructions at Southwest Pass No vessels have grounded on the bar, to the best of my information, although many have passed over.

The river at this place (New Orleans) stands 6 feet below high-water mark of 1862, and a flood equal to that of 1862 is anticipated.

Report of April 1.

Repairs were not completed until the 8th of March, on which day the Essayons sailed for Southwest Pass. She arrived there on the 9th, and recommenced work on the 10th, under the most adverse circumstances. At that date the 19-foot channel we had left when suspending work in February, and which had retained (according to the best information) the dimensious left in February, until about the 1st of March, was found filled in by deposit so as to give but 15 feet, and the bar had moved out into the Gulf a distance of about 400 feet. There was also a large ship aground in and across the channel, obstructing the latter so completely that, after five hours spent in the attempt, we were unable to pass out or do effective work.

Afterward the tow-boats succeeded in dragging the ship off the bar, and we started out, but were stopped by an attempt on the part of the tow-boat captain in charge to run us down. In the effort to prevent a collision we broke a blade of the excavating propeller. The ship was then again forced on the bar, and anchored so as to again blockade it.

On the 11th, at the urgent request of the United States district attorney, charged with the defense of the suit of Wolfley rs. Humphreys et al. the "Essayons" was ordered to New Orleans that her officers might be able to appear as witnesses in suit named. During her stay in New Orleans a new blade was put in the propeller.

On the 20th she again left for Southwest Pass, arriving there on the 21st, and working on the bar eight hours that day. During the 22d she worked 9 hours, but with so much interruption from vessels, in and out, that but little was accomplished. The 23d and 24th were stormy, and the bar blockaded. On the 25th, with the bar yet blocked, we succeeded in working two hours.

Steps I had taken to assume control of the bar to such extent as might be necessary for the interests of the work. at this date induced the managers of the tow-boat association to agree not to interfere with the work, as they had before done by grounding vessels on the bar at improper times and blocking it.

Since the results of our work have been for each day noticeably good, viz, on the 27th there was reported 164 feet at low tide; on the 28th, 17 feet low tide, and on the 30th, 18 feet at low tide, with a channel width of 100 feet.

During the time of this work the river stood at 24 feet below the high-water mark of 1862, as noted at New Orleans.

NOTE.-Since found to be a mistake caused by moving old gauge, and placing highwater mark 1 foot and 63 tenths too high.

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Report of May 2.

From the 30th of March to the 4th of April the weather was very stormy and the bar too rough for work. During this time the channel filled in so as to leave only 164 feet on the crest of the bar. On the 4th work was commenced and two blades of the excavating propeller broken. These were replaced, and work recommenced April 13th.

Between the 13th and the 28th the Essayons could only work on the bar forty-five hours, on account of bad weather. In this short time favorable for work she deepened the channel to 184 feet from 16 feet.

Two blades were broken on the 28th. The "Essayons" arrived here yesterday and went into dock this morning.

The hub will now be fitted with pointed blades. This work will be completed in two or three days.

No monthly reports for May and June have been rendered. Their place is supplied by the following statement of work to the close of the fiscal year.

Work was resumed on the 8th of May, with a channel over 18 feet deep; continued on the 9th, and suspended on the 10th by a severe storm, which filled the channel so that on the 11th soundings only indicated 16 feet. The 11th, 12th, 13th, and 15th afforded twenty-six

hours' working, which had only the effect of deepening the channel above and below the crest of the bar. On the 16th six and a half hours work resulted in cutting through this crest and increasing the depth to 173 feet.

Between the 16th and 28th storms prevented work, except at intervals, twenty hours and a half in the aggregate. On the latter date the depth of the channel was reported at 173 feet, with but three sounds of less than 18 feet. Stormy weather again prevented work until June 1st, when, after eight hours' working, a depth of 17 feet was reported. A storm of more than usual violence then set in and prevented work until the 7th, on which date, and on the 8th, seventeen and a half hours' work were accomplished, opening the channel, which, during the storm had filled to 15 feet, so as to give 163 feet. Another severe storm, lasting four days, then put a stop to work and refilled the channel to 16 feet.

From the 13th to the 23d forty-two and a half hours' work was performed, giving on the latter date a depth reported at 17 feet, large. Five days of this period were spent in resupplying the dredge-boat with coal, provisions, and other stores needed to last for the next two months. On the 25th, 18 feet was reported, and the same for each succeeding day until the 30th, when 183 feet for a width of channel of 250 feet was found available.

On the 30th the ship Francis P. Sage, drawing 19 feet, passed out without the least trouble.

The two months covered by this portion of my report were remarkably unfavorable for work at Southwest Pass, where the effect of storms is not only felt during their continuance, but often for several days afterward, owing to the exposure of the bar to every southerly storm, and to the heavy swell resulting from waves which have an unchecked fetch across the whole width of the Gulf. Even storms which expend themselves over the Gulf cause a rough bar, and from this effect of such storms we have been obliged to suspend work on days at Southwest Pass calm and without a cloud in the sky. During the months of April, May, and June, twenty-seven such days were recorded on which either work was partially or wholly suspended.

In concluding this account of this past year's work I cannot show the value of its results better than by calling attention to the fact that no blockade has occurred during the year such as has occurred every previous year.

Of the great number of vessels engaged in the commerce of this port but a very few since November 1, 1870, have met with detention on the bar; none have been detained longer than a few days, and of these the majority have been grounded outside of the channel at times when there was at least 18 feet available at mean low tide, and the channel marked by a line of spar-buoys on each side. No other year has passed without a blockade, and the detention of a large fleet for weeks and even for months. During previous years even steamers have been obliged to obtain the assistance of tow-boats at great expense, and then be detained for days. During the past year I know of but one steamer (the Western Metropolis, draught 183 feet) that has been at such expense, and she only incurred it because her pilot ran her out of the channel and into 12 feet of water.

A NEW DREDGE-BOAT.

In the early part of the fiscal year Congress made appropriation sufficient to admit of the construction of another dredge-boat. Before

commencing this construction a thorough trial of the new machinery applied to the Essayons was considered desirable.

On January 12, 1871, I was able to report this trial satisfactory, and recommended that contract for the new boat be made as soon as prac ticable, the vessel only to differ from the one in use in certain points specified in my letter.

The recommendation was concurred in by the chief of engineers and authority given me to prepare drawings and specifications and to advertise for bids from ship-builders.

With the assistance of Mr. Edward Marsland (a man of ability and long practical experience as a mechanic and steam engineer) the necessary specifications were completed and advertisements issued on the 23d of March.

In response bids were received as set forth in the following abstract: Abstract of bids received for the construction, equipment, and delivery at New Orleans, La., of a dredge-boat for improving the mouth of the Mississippi River.

The lowest bid for construction with an iron hull being greater than the available amount of the appropriation would admit, that for a wooden hull was accepted, and the contract was awarded to Mr. John Roach, he being the lowest bidder.

Mr. Roach entered into contract and commenced work on the machinery in May. On the 30th of June work on both hull and machinery was well advanced.

The contractor has agreed to deliver the vessel fully equipped and ready for work in New Orleans on or before the 1st of January, 1872; he expects to deliver at an earlier date. There is good reason to feel gratified in every way with the contract, the work being in the hands of as good builders as there are in New York, and the terms being nearly $5,000 less than for the "Essayons," although the dimensions of the hull are greater and the machinery more expensive.

I have employed two thoroughly reliable inspectors to superintend the work, and insure the use of none but the best material and workmanship.

It is greatly to be regretted that the amount of appropriation available was not sufficient to warrant the construction of an iron hull. When we consider that the latter would live about twice as long as a wooden hull, the few thousand dollars difference in cost appears insignificant.