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and after using remeasured. The depth reported is the least depth obtained by cross, diagonal, and longitudinal soundings, between buoys located by triangulation; in many cases but one, two, or three sound. ings 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 draw. ing 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 com. mercial value of the channel.
For example, in February, the depth reported was from 16 to 164 feet + tide 2 feet = 18 to 181 + 1 foot mud = 19 to 194 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 chan. nel, (164 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 saine 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, 1870, 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 860,000 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 Tow. boat 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 aud 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 channel 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-honse, 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 ont of sight. The inspector took our prepared line, carefully measureal 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 deer, 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 takep 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.
Balance in the Treasury of the United States July 1, 1873..
penses $150,000, repair of dredge $100,000 Total amount appropriated since June, 1869... Total expended since June, 1869...
$35 083 00
7,748 55 30,000 00 130,000 00 117,503 40 135, 328 15
250, 000 00 984, 883 53 849, 555 38
Tabular statement to accompany annual report for the year ending June 30, 1874, on the improvement of the mouth of the Mississippi River.
Ta ular statement to ac ompany annual report for the year ending June 30, 1874, 8c.—Continued.
N. N E. N. E.
5 25 1 45
Pass à Loutre
Finished repairs. Essayons started
for Pass à Loutre.
out, grounded north of north line
assisted by Essayons.
stance and broke blade No. 3,
grounded north side of channel.
edonian got off bar. Essayong
oxcavator, Essayons at New Orleans.
8 0 8 0 6 55
N. N. W.
4 5 6
8.9 9. 2 9.5
6 10 6 10 6 10