PROJECT FOR THE YEAR ENDING JUNE 30, 1875. The work will be continued as heretofore. Both dredges will be kept at Pass à Loutre during the summer with but one crew. In October the McAlester will be repaired and put on duty at the bar. The Essayons will then be brought up, repaired, and retained in port until the river rises. Afterward, both dredges will be kept at the bar. Should it prove advisable, one boat will be sent occasionally to Southwest Pass to keep the channel there in fair condition for the passage of light-draught vessels. The work is not susceptible of permanent completion. It is located in the collection-district of New Orleans and near the light-house at Pass à Loutre. GENERAL REMARKS. The recent legislation giving the Secretary of War authority to estab lish and enforce certain regulations governing the use of the pass improved, although regulations have not yet been drawn, has already had a beneficial effect. The facts on which it was based were not generally known, and the monopoly at which it struck was in a position to overawe its victims. This is now changed. The monopoly has been broken down, and in its place we have a very promising opposition in the towage business. Pilots, ship-masters, and ship-agents are resuming their proper authority, and, understanding the necessity for a system of laws, to govern their action, that looks to the general good rather than the aggrandizement of a corporation, are acting now very much as they should. For example-many pilots are taking greater pains to familiarize themselves with the channel; masters frequently wait for a high tide when their vessels are deeply laden; agents of steamers, when it is necessary, take tow-boats to insure crossing the bar without detention, and the towboat companies are willing to render such assistance without waiting for the vessel to get hard aground. These are but a few indications of a growing, healthy, commercial sentiment, which, properly fostered, will make dredging as beneficial to commerce as it may be made, and place the efforts of the Government at their proper value. The depths of channel given in this report, it should be observed, have been obtained by reducing the actual soundings to the plane of extreme low tide for the year. This departure from the usual rule, adopted in hydrographic work of reducing to mean low-tide, was made for the purpose of inducing greater care on the part of persons using the channel, and has, I think, been of practical benefit. I have not worked up my records from self-registering gauges so as to ascertain how far the plane of mean low-tide is above that of extreme low, but an inspection of the records indicates that the difference is between 8 and 10 inches. Great care has been taken in making the soundings, men being employed who have, by constant practice, become expert and give the surface even where the bottom is softest. Mushroom leads have been used, and their length not included in the measurement of the sounding-line-this length is about four inches. The lines were the best close-laid attainable in this market. These have been wetted, thoroughly shrunk and measured each time before using, and after using remeasured. The depth reported is the least depth ob tained by cross, diagonal, and longitudinal soundings, between buoys located by triangulation; in many cases but one, two, or three soundings for this least depth have been obtained from the whole number, of from 600 to 800 soundings made in the channel. The width of channel reported is also the least width. This statement goes some way toward explaining why vessels drawing from 2 to 4 feet more water than reported in the channel have passed the bar without detention. Adding to the depth reported, the height of tides as shown by the preceding table, and one foot for semifluid mud, gives the actual commercial value of the channel. For example, in February, the depth reported was from 16 to 163 feet + tide 2 feet = 18 to 18 + 1 foot mud = 19 to 19 feet. During this month a 20-foot vessel was delayed 146 hours, one drawing less than 15 feet 10 hours. No other vessels were delayed. The 20-foot vessel (a steamship) delayed had a jury rigging for her rudder, and grounded because unable to steer properly. A sailing vessel drawing 19 feet 7 inches, with the same depth of channel, (163 feet,) passed out a few days ago with but two hours' detention. With the dredges now employed, and the manner of obtaining and reporting depth and width of channel, my reports do not show the maintenance, throughout any one year, of a channel 18 feet deep and 300 feet wide. Depths of from 17 to 20 feet at extreme low tide are frequently reported, but never a width of 300 feet for those depths. Yet it was reported that in 1859 and 1860, for a whole year, a depth of 18 feet and a width of 300 feet was maintained by simply dragging harrows and scrapers over the bar at Southwest Pass, and at a cost of only $60,000. Also, that under the contract of Craig & Rightor the same depth and width was obtained at Southwest Pass and Pass à Loutre, the latter by exploding a few hundred pounds of gunpowder on the bar. My experience on this work during 1869, 1879, and 1871 convinced me that there was something wrong about the measurements on which these reports were based. If not, then we were spending $150,000 a year with a plant worth $500,000, when as good results might be obtained for $60,000 a year. I investigated the matter. I questioned pilots, tow-boat captains, ship-masters, and employés of the contractors who received pay for the results reported. The information so obtained could not be put in shape for report, for the reason that while the men interviewed would freely tell me what they knew they were unwilling to sign written statements. A few months ago a suit for libel was brought against me by the Towboat Association, which offered an opportunity to bring this testimony out; but the suit was withdrawn and costs paid by the plaintiff. In view of the fact that I have satisfied myself that the depths and widths of channel reported in 1853, 1857, 1858, 1859, and 1860 have been erroneously reported, it seems proper to state my grounds for belief. There are many tricks about sounding that, while generally known to sea-faring men, are unknown to or escape the observation of the most conscientious and careful inspectors. I will explain some of them. There are various qualities of lead-lines; all shrink more or less on being wetted. Experiments I had made with several qualities found in this market resulted in showing a shrinkage of from 6 inches to 2 feet in a length of 20 feet. An inspector who does not select his lines and measure them himself when thoroughly wetted, neglects a prime precaution against getting wrong results. There are various shapes and sizes of leads suited to different kinds of soundings. Where the water is only about 20 feet deep and the bottom soft, as at the mouth of the Mississippi, accurate results can only be obtained with a light, flat lead, since a long lead, and especially a heavy one, though well thrown, will sink a great part of its length into the bottom, and, whether the lead-line be measured from the lower or upper end of the lead, wrong results are obtained. Then much depends on the honesty of the leadsman. Even when the water is smooth, it requires an experienced and close observer to determine if he be not calling from 6 to 12 inches more or less than the actual sounding. In rough water it is yet more difficult to detect error of this kind, since the leadsman himself must average the rise and fall of the waves to give the true sounding. It will be seen from this how, even ascribing to contractors and leadsmen average honesty, and to inspectors average knowledge of and attention to what has been stated above, erroneous results may be ob tained. Returning to the works of 1853, 1857, 1858, 1859, and 1860, all my informants agree that those works at no time afforded a chanuel more than 16 feet in depth at mean low-tide. Why was a greater depth reported ? The contractors provided the leadsman leads and lead-lines; the leads were long and heavy, such as used for off-shore soundings; the lines were measured dry, and from the lower end of the lead; the soundings were often taken from the bow of a steamer, with the inspector in the pilot-house, watching the leadsman as well as he could, recording the calls, and his attention distracted as much as possible by the conversation of persons about him. In one case they were taken from boats, one on either side of the steamer, at a distance of 150 feet from the latter, with the inspector on the steamer. These soundings, it was thought, were verified by triangulation, the inspector and his assistant using the instruments from stations on mudlumps distant from the channel, while soundings located were made from small boats by the contractor's employés. My informants were, some of them, at the time cognizant of the fact that the inspectors were being systematically deceived, as I have indicated. I give the statement of a master of a dredge-boat, as near as I can remember it, as a sample of my information: We had a channel between 15 and 16 feet deep; the contractors reported it 18 feet deep and called for inspection. I was notified that the inspector would be down on a certain day. I selected the most loosely-laid lead-line I had and stretched it over the boiler of the boat, fastening it at one end and attaching a weight at the other. When the inspector came aboard, the line was thoroughly dry and stretched. Our other lines were put out of sight. The inspector took our prepared line, carefully measured and marked it himself. We then ran down to the bar. As we neared the bar the leadsman was instructed to take soundings in water that we knew was over 18 feet deep, ostensibly to show the depth above the bar, but really to wet the line so that it would be properly shrunk before using on the bar. We then sounded back and forth through the channel, the inspector standing by the leadsman and watching every throw, as if he thought he could judge from mere sight whether the leadsman was throwing and calling honestly or not. There resulted the reporting of a channel over 18 feet deep at mean low-tide, when there was really not a channel 16 feet deep. The result not only deceived the inspector, but exceeded my expectations, as I had taken pains to impress on the inspector the fact that shoaling in the channel was rap idly effected, and that a little less than 18 feet might possibly be found for one or two soundings. This was the subject of remark after completing the inspection, but the inspector did not think of again measuring the lead-line, nor would such a course have enlightened him, for as soon as the soundings were completed I had it put out of sight and another line exactly like it and properly measured substituted for it. This is the substance of what one witness stated to me in conversation. This exposé appears necessary to put the work of to-day in its proper light when comparison between it and past works is attempted. It may also suggest to future inspectors some points of value. Financial statement. Balance in the Treasury of the United States July 1, 1873.. $85 083 00 7,748 55 30,000 00 130,000 00 Amount expended during the fiscal year ending June 30, 1874. 117,503 40 135,328 15 Amount required for the fiscal year ending June 30, 1876, running ex penses $150,000, repair of dredge $100,000. 250,000 00 Total amount appropriated since June, 1869.. 984,883 53 Total expended since June, 1869.... 849,555 38 |