Sundry expenses for traveling, etc Total.... 85.36 2,962. 01 Of the amount thus expended the instruments and camp outfit are still available for future work. Assuming a depreciation in value of the instruments of 10 per cent and of the camp outfit of 50 per cent of the original cost, the following would represent the actual cost of the survey: $30.50 151. 19 2, 354.63 Total.... 2, 536.32 This gives the average cost per square mile of survey, all expenses incidental to the work. Very respectfully, your obedient servant, DAVID MOLITOR, First Lieut. CHARLES S. RICHÉ, Corps of Engineers, U. S. A. II.--REPORT OF MR. E. E. HASKELL, ASSISTANT ENGINEER. UNITED STATES ENGINEER OFFICE, Sault Ste. Marie, Mich., April 28, 1894. SIR: I have the honor to submit the following report upon the reduction of the observations of the line of precise levels run by Messrs. E. J. Thomas and A. O. Wheeler in June, 1892, between B. M. "A" on the canal lock of 1881, at Sault Ste. Marie, and the water gauge at Waiska Bay. In my last annual report (p. 4359 of the Report of the Chief of Engineers, U. S. A., for 1893) I made the statement that the elevation of the zero of the water gauge at Waiska Bay should be corrected by a minus 0.152 foot, the difference in the elevation of B. M. "F" and B. M. "A." From the final computations of the levels it appears that Mr. Thomas must have had the elevation of B. M. "A" and called it B. M. "F," so that there is no correction to the elevation of the zero of the gauge at Waiska Bay as indicated in my report. B. M. "F" is the only one mentioned in the notes as the starting point for this line of levels, but the elevation of it or of the bench mark used does not appear, which accounts for my being led astray in my first interpretation of them. In regard to the connection of this line of levels with the gauge at Waiska Bay we are dependent upon the statement made in the field report, which is undoubtedly correct, as to the elevation of its zero. In the notes there is no statement as to how the connection was made. In connection with the reduction of the observations I have determined the constants of the precise level, Kern No. 2, with which this line was run and these new values have been used in the computations. These values are given below: Wire interval between extreme wires equals 1.038 for a base of 100+ƒ+c where f=0.366 and c=0.177. Hence d, the distance, equals 96.34 S+0.54 where s equals any intercept on the rod. The value of one division of the level tube of the striding level was determined by means of a level trier, and found equal to 4'.801. The inequality of the collars was determined by the striding level with the result eye-end collar 0.53 of a division of the level tube, or 2.544 larger than object-end collar. The observers were very careful indeed to make back and fore sights equal, so that in the whole line of 14 miles of double line run there is only two or three stretches where any corrections appear. From my computations the zero of the Waiska Bay gauge is 1.1497 meters 3.7720 feet below B. M. "A," agreeing closely with the value given in the field report of the work. There were four P. B. M.'s determined, located at intervals along the line, and the elevation of these, together with the descriptions of them, are given below: Elevation above mean sea level of B. M. “ A on northwest wide wall of canal lock of 1881605.872 feet: 184.668 meters. 641.312 feet 195.682 meters. 195.470 meters. 204.312 meters. Elevation of P. B. M. No. 1 above same reference=642.007 feet 197.517 meters. 602.099 feet: = 183.518 meters. DESCRIPTION OF BENCH MARKS. "P. B. M. No. 1 is the top of a copper bolt set in the top of a large bowlder. The bowlder is 12 feet west from the center line of the Duluth, South Shore and Atlantic Railroad, and about 200 yards north of the 3-mile post, and is marked with the letters U. S. B. M., cut into the surface on the cast side. "P. B. M. No. 2 is the top of a copper bolt in the center of a stone that is buried 4 feet deep. The stone is on the west sido of the Duluth, South Shore and Atlantic Railroad, 30 feet west from the center line of the track and 45 feet north of the 6mile post. A tamarac post, 6 inches in diameter, sets upon the stone, and projects about 16 inches above the surface of the ground. "P. B. M. No. 3 is on the west side of the Duluth, South Shore and Atlantic Railroad, 21.5 feet north from the 9-mile post, and 31 feet west from center of railroad track. It is the top of a copper bolt set in a square stone that is buried about 4 feet deep. A cedar post sets on the stone and projects 16 inches above surface of ground. "P. B. M. No. 4 is the top of a copper bolt set in a stone that is about 18 inchies square and buried 4 feet in the ground. The stone is 34 feet north from the center line of the Duluth, South Shore and Atlantic Railroad, and 192 feet west from the west end of the railroad bridge across Waiska River, at Bay Mills station, almost due north from the frog on the branch line turning out to Waiska Bay. A cedar post 6 inches in diameter sets upon the stone and projects 2 feet above the ground. The letters U. S. B. M. are carved in the south side of the post." SLOPE OF THE RIVER. The Bay Mills gauge was read daily between 8 and 8:30 a. m. from June 6 to Sep, tember 9, 1892, inclusive. The elevation of the mean reading from this series of observations, or the mean lake level for this period, equals 601.826 feet above mean sea level. The gauge at the head of the canal at Sault Ste. Marie is read daily at noon. The elevation of the mean reading for the period given above is 601.412 feet above mean sea level, making the slope of the river from the Bay Mills gauge to the head of the canal 0.414 feet, or 0.037 feet per mile, the distance between the two gauges being in the most direct line by the channel 11.3 miles. This determination of the slope for this reach is of course not as satisfactory as if the gauges had been read simultaneously, but can be considered a close approximation. In view of the excellent opportunities offered at Point Iroquois Light-House for establishing a gauge and the possibility of having the light-keeper read it daily for the period of a year at least, I would respectfully recommend the continuing of this line of precise levels from P. B. M. No. 4 to Point Iroquois Light-House. This distance is only 6 miles over a reasonably good road, representing not to exceed 4 days' work for the ordinary leveling party. The angle party of the primary triangulation could do this work at very small expense while they are occupying A Iroquois, which is in the vicinity. Very respectfully, your obedient servant, First Lieut. CHARLES S. RICHÉ, Corps of Engineers, U. S. Army. E. E. HASKELL, DDD 2. REEXAMINATION OF ST. LAWRENCE RIVER. REPORT OF CAPT. SMITH S. LEACH, CORPS OF ENGINEERS. UNITED STATES ENGINEER OFFICE, Burlington, Vt., July 1, 1894. GENERAL: I have the honor to transmit herewith my annual report on the reexamination of the St. Lawrence River under an allotment from the appropriation for survey of Northern and Northwestern Lakes, 1891. Very respectfully, your obedient servant, Brig. Gen. THOMAS L. CASEY, Chief of Engineers, Ú. S. A. SMITH S. LEACH, Captain, Corps of Engineers. An allotment of $4,275 was made May 2, 1893, and became available on July 1 following. It was based on the estimated cost of a resurvey of the main ship channel for a width of 2,000 feet from Lake Ontario to the foot of the Brockville Narrows, at Morristown, a distance of 40 miles. Owing to the very uneven conformation of the bed of this part of the St. Lawrence the method of isolated soundings heretofore employed in all hydrographic surveys of a general character was inherently defective, and several shoals not disclosed by the original survey had been reported. It was desired to examine the part of the channel used by deep-draft vessels under such conditions as to leave no possibility of points of rock which could be touched by vessels remaining undiscovered. It was decided to employ the method of continuous sweeping, for many years in use in verifying the removal of rock to certain spec ified planes, but never before adapted to use on such a large scale. The apparatus devised and the method of working it are described in this report in a general way only, as the work remains unfinished and some details will be modified in future. A decked scow, 60 by 15 feet, was anchored near mid-channel. Two anchors, one backing the other, were used, and in placing the scow the anchors were let go, the proper length of cable paid out, and the tug made fast alongside, head downstream, and worked at full throttle until the anchors held the strain without dragging. If they failed to hold, they were raised and thrown again a little to one side of their first position. At the stern of the scow the end of a three-eighth-inch steel wire cable was made fast, and the cable was run out, with can buoys attached at intervals of 250 feet, until 2,750 feet were in the water. This part of the cable was called the permanent radius, and was the shortest line used until near the end of the season, when work was begun at 2,000 and finally at 1,700 feet from the scow. The last distance was found inconveniently short for a full sweep of 2,000 feet, but that or even less will do for narrow channels. At the lower end of this permanent radius a thimble was placed in the cable, and a second cable, called the variable radius, was made fast by a pair of sister hooks. The variable radius was arranged to take buoys every 175 feet, that being half the length covered at each sweep. This length was selected in order that the eyes permanently wired to the cable to receive the buoys might also be the distance graduations, to avoid the possibility of error. The sweep was composed of a float or raft of cedar, in sections 20 feet long, and of a line of 2-inch gas pipes of the same length, depending from the float by wire cables. The float sections were strongly and flexibly connected, and the gas pipes were joined by toggles. The joints of the pipe were vertically below those of the float, so that the whole system consisted of a series of flexible parallelograms, each length of pipe being always parallel to the corresponding section of the float. Each of the suspending cables turned 90° over a pulley and was lashed to a cable running the entire length of the float, called the "messenger." By hauling on the "messenger" all the suspending wires were lifted equally and simultaneously, or in other words the line of gas pipe was lifted parallel to its first position, but higher in the water. Two sweeps were used, having 9 and 10 sections, or 180 and 200 feet length. The tug was placed between them, the shorter one upstream, and having the radius cable attached to its upper end. The axes of the sweeps were parallel with and that of the tug athwart the current. Guy lines to bow and stern of the tug kept the system in the desired position. The space under the boat was filled by a length of pipe dropped over the bow and hanging from the gunwales, and which con.. nected the two sweeps, making a line of pipe 390 feet long up and down stream and 21 feet below the low-water plane. At each swarth the radius cable was lengthened 350 feet, so that there was a lap of 40 feet to insure against gaps. By working the engine ahead or backward the entire system was moved across the channel, running parallel to itself and following the arc of a curve determined by the radius. The indicating device was simple and very efficient. At every second suspending cable a staff was placed, submerged about 4 feet and attached at its lower end by a spring-clip to the suspending cable. It was pivoted on the float in the plane of the cable and extended 6 feet above the water with a flag at the top. It thus prolonged and made visible the direction of the cable extending from the float to the pipe. Itis plain that, if in moving across the channel the pipe met any obstruction, it would be held fast while the float moved on, so that the suspending wire, and consequently the staffs, would be inclined in the direction of motion. The effect was very pronounced, the "bowing" of the staff's being plainly and instantly visible. The boat was stopped in such cases and the messenger hauled in until the staffs resumed the vertical position, which they did suddenly and with a movement not to be mistaken. At that moment the messenger was stopped and the position of a zero point read on a scale which gave directly the depth of the pipes below the datum plane. That depth was recorded as the least depth on the shoal. At the same time a buoy was dropped on the highest point of the shoal. At first the buoy was located by transit intersections and quite independently of the sweeping apparatus. Observation of the accuracy with which the striking of known shoals could be predicted inspired such confidence in the sweep as a position indicator that one transit cut was abandoned, and locations were made by the arc described by the point of the sweep where the shoal struck and one transit observation. Under the latter method the transit station was always chosen so as to rake the channel, thus making the lateral, or most important coordinate, depend wholly on the transit. To check against any error from the dragging of the scow ancnor during the sweeping a tell-tale buoy was anchored alongside the scow, which showed any movement of the latter by casual observation. Preparations were begun early in July, and the party reached the point of beginning work at Sister Island on the 21st. After many vexatious delays, due to storms, discourtesy of captains of vessels, the novelty of the undertaking, and the incompetence of the crew of the chartered tug the work was closed on September 19 at the head of Brockville Narrows, 9 miles from the point of beginning. In this distance 14 new shoals were discovered, the positions of which were reported immediately after the close of fieldwork. Tri-daily observations were made at Charlotte and at Oswego, N. Y., on Lake Ontario, from. July 1, 1893, to June 30, 1894; at Erie Harbor, Pa., Ashtabula and Cleveland, Ohio, and Monroe, Mich., on Lake Erie; at Milwaukee, Wis., on Lake Michigan; and at Escanaba, Mich., on Green Bay, from July 1 to December 16, 1893, and from March 19 to June 30, 1894. Daily observations were made at Sand Beach, Mich., on Lake Huron, and at Sault Ste. Marie and Marquette, Mich., on Lake Superior, from July 1, 1893, to June 30, 1894. The accompanying table is a continuation of that published in the Annual Report of the Chief of Engineers for 1893, Part VI., p. 4381: Monthly mean of water levels for the several stations below the planes of reference adopted Stations. 1893. in 1876. 1894. July. Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May. June. |