The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

. eUeF, 420 foot spot you understand why it is a a shoal 30 years en ec rate : tained in the wire, which holds it taut shoal. ago, and was not surveyed in many cases. A good many spots of that kind are still to be discovered. "Another thing you have never had, but it seems to me you need for sound navigation, is a better knowledge of depths out in midlake, away from the shores. There are a great many blocks on the Lakes with 500 square miles in each where we have no soundings what- We hope to sound these in the next few years. "The 'final reason why we want to do considerable more work, examining the bottom and searching for shoals and - wrecks is because modern methods and equipment allow us to work so much bet- ter now than in the past. We can find obstacles very easily. now, that were al- most impossible of discovery by the old lead line method of work. We now sweep where the old surveys sounded with a lead line. The lead line is all right in its place, but its place isnot on 'a hydrographic survey. No wrecking master would look for a wreck with a. lead; he would drag for it. But a drag is a slow, clumsy affair that cannot suc- cessfully be used on extended surveys because the cost runs up too fast. You know what a drag is? A long weight- ed line w:th a tug at each end, and the tugs run abreast with the line stretched between them dragging on the bottom. It will locate a wreck, but it costs a good deal to do it. You also know what a sweep is, as it is used on the dredge cuts in St. Mary's river and in the lower Detroit river--a raft with iron bar sus- pended at a fixed depth. But the bar sweep is too slow also. "Out in the open lake we needed some- thing that would cover several square miles in a day's work, and something that would not have to be towed into a har- bor at night. "We have succeeded in 'perfecting a tension wire sweep that will examine 5 to 10 square miles i a day's work,-- sweeping and sounding at the same time, --and when the day's work is done the sweep is reeled up on the deck of the steamer. The wire sweep is a Lake Sur- vey invention, but it has been adopted by the Coast and Geodetic Survey for use on salt water also. It is very sim- ple--a little over a quarter of a mile of steel wire, or small cable a tenth of an -inch in diameter, is run out with a launch on each side of the survey steamer. The wire is buoyed every 100 feet, suspend- _ ing it at 30 feet below tae water sur- face, and held down by weights. When each launch has its full length of wire stretched out, the steamer and the two launches wing-and- -wing proceed on par- allel courses. Each launch heads a lit- THe Marine REVIEW tle outside' of its course, and in that way a tension of! about 150 pounds' is main- and level. The sweep covers a belt half a mile wide, moves at a speed of about two miles, and so sweeps a square mile in-an hour. At the same time soundings are taken from the survey steamer and -- less both launches. Everything with than 30 feet of water on it is detected, - whether it is a shoal, a boulder or a lone spar, reaching up from a deep lying wreck. When an area has been swept it may be certified clear of obstacles. "No method of sounding alone can certify the bottom. Pinnacle rocks, boulders or spars are likely to stick up between the soundings. Now that we have found a practicable inexpensive method of sweeping, we propose to do a great deal of it. "The crucial test, as to whether sur- veys are needed on the Lakes or not, is this: Do we find anything? On_ this question we stand squarely on our rec- ord. We always get something. One party discovered 31 new shoals on the St. Lawrence river in one season. Three new shoals were discovered in Lake Erie in as many weeks. During the past season our steamer Search swept east of Thunder Bay Island and found a shoal and a wreck. Then the Search went up to the north end of Lake Michigan. and located four new shoals, and in the fall she swept in the Straits and picked up three more new shoals. -On account of these new shoals in the Straits the sail- ing course was moved about a mile to the northward. This is only part of the work of the Search for the past sea- son, but she found eight new shoals and one dangerous wreck. "At the same time the Gen. Williams was sweeping 'in Lake Erie, and she dis- covered three new shoals and_ three wrecks. And this is only part of her work, "Our small steamer, the No. 1, with a small party, was engaged mostly on Lake Michigan harbors, but she located the new shoal off Grosse Point, where the Reed went on, and spent about a month searching for Capt. Whitney's shoal. When we find that we will call it the Whitney Shoal. In addition the No. r did some work preparatory to the extensive survey of the south end of Lake Michigan we expect to begin the coming season. "Our steamer, the Surveyor, was not in commission, we did not have money enough to operate her, and our small steamer No. 2 is having a rebuild. "We have blocked out surveys 'enough to engage our fleet for the next 10 or 12 years, and are asking Congress to put us on a continuing basis,--that is, assure us a certain length of life on a large scale, inorder that -we 'can. economically and persistently complete the adequate survéy ofthe Lakes. complished a much smaller organization can handle the work of issuing charts and bulletins and making such small sur- veys as progressive changes warrant, "We expect to sweep Manitou Passage next spring, and open it again for deep draft boats. There are doubtless some isolated boulders in there not shown by soundings. "In our general project, we expect to work in Lake Superior from Sand Island westward, do considerable work about Isle Royal, do some work in the approach to Whitefish Bay and the St. r.ver.; south ends of the lake; and along the Mary's whole west shore, from Sturgeon Bay Canal southward. We continue work in the vicinity of the Straits and sound along the west shore of Lake Huron, | Saginaw Bay, and from Pt, Aux Barques to Port Huron; also the east and west ends of Lakes Erie and Ontario; and, as I said before, the middle of all the Lakes: It is a big undertaking, but is fully warranted by the needs and impor- tance of the commerce of this great in- land waterway. "I intended to say something | about Lake levels,--but I am using up too: much time. Major Keller has put in your hands our Hydrograph of the Lakes, showing monthly stages from 1860 to the past November. It will pay you to study this and find out to what extent the loading capacity of your vessels is dependent upon the caprice of nature. You will find that in November, 1895, Lake Erie was 1.6 feet lower than it is now. This means a loss of 16 per cent of your carrying capacity. that Chicago alone wants enough water .to cut the lakes down over 8 inches, and the power companies at Niagara Falls want some water that may cut down the Niagara River "aad possibly Lake Erie also. "Now, I am not sure that an inde- pendent outlet at Chicago and an in- creased flow capacity in the Niagara river are evils from the point of view of navigation on the Lakes, but unless we have regulation the evil is unques- tionable. Regulation is sure to come be- cause, otherwise lower water by half a foot than that of 1895 is in store for navigation. The hydraulics of the riv- ers, and the gathering of data on Lake levels needed to solve this vastly impor- tant subject, has been part of the work of the Lake Survey and must be con- tinued. "Now, to summarize, I believe there are a lot of things the Lake Survey can give you. You want navigators' charts, and you want them kept up to date. After that is ac. in Lake Michigan, the north and Remember ~ See