during the time of sounding, and the soundings reduced to what they would have been if the water surface had been 19 feet above grade. The computation of the contents of the prism is not yet completed. When this is done we will have the means of estimating, with great accuracy, the quantity of material to be removed from this portion of the work; and it is proposed to eventually extend the method over the remaining portion of the projected improvement. This work is located in the Superior collection district, Michigan. Sault Ste. Marie is a subport of entry, Marquette, Mich., being the nearest port of entry. It is nearly midway between the light-houses at Round Island and Detour. Money statement. Amount received from sale of fuel ...... Amount appropriated by act passed August 2, 1882 July 1, 1883, amount expended during fiscal year, exclusive of outstanding liabilities July 1, 1882. July 1, 1883, outstanding liabilities July 1, 1883, amount available................ 13, 722 41 186, 316 97 .1, 927, 292 00 Amount (estimated) required for completion of existing project...... Abstract of bids for dredging on the Middle Neebish, Saint Mary's River, Michigan, receired and opened by Maj. F. U. Farquhar, Corps of Engineers, on February 28, 1883, in accordance with advertisement dated January 30, 1883. ance. Contract awarded to John Hickler. Bank measurement recommended for accept JJ 2. IMPROVEMENT OF THE SAINT MARY'S FALLS CANAL AND SAINT MARY'S RIVER, MICHIGAN. IMPROVING THE CANAL. Although the canal has been available for practical navigation since the 1st September, 1881, yet much has remained and still remains to be done, in order to fully complete the work. During the fiscal year the following has been accomplished: In October, 1882, three cribs were sunk above and two below the new lock. These form an extension to the west and east bulkheads. The superstructure was completed in May, 1883. A slope wall, beginning near the pump-house, and extending southward 250 feet, with an average height of 20 feet along the face, has been built, mostly by the lockmen when not engaged in locking. In the same way a small house for tools, near the movable dam, and a scow 96 feet long by 18 feet wide, and 5 feet deep, has been built. IMPROVING THE RIVER. Two dredges belonging to John Hickler were employed by the hour in deepening the approaches above and below the canal. The average increase in the depth of water was 4 feet, to accomplish which 10,912 cubic yards of material, scow measurement, were removed. The dredges were employed on this work a total of one thousand and sixty hours. After the dredging was completed the drill-scow was brought up from Sailor's Encampment, and the bowlders removed from three-fourths of the area. The drill-scow was employed on this work thirty-four days. The drill-scow with a party of twelve men, under charge of Mr. Hursley, worked seventy-seven days on the shoal near Sailor's Encampment. The bottom was first drilled and blasted, and the broken fragments of rock were then chained by a diver, and hoisted onto the scow. In this way an area of 1,200 square yards of bottom was cleaned to a depth of 17 feet, making a straight channel 100 feet wide, with a uniform depth of 17 feet, over this shoal. An area of about 2,700 square yards, having an average depth of 15 feet of water, still remains. During the winter the drill-scow was strengthened by a system of bracing extending from each corner to the one diagonally opposite. A house that was formerly used on the river survey has been placed on a scow belonging to the Government, refitted, and is now in use at the Middle Neebish; it will accommodate six officers and twelve men. EAST NEEBISH. The west channel of East Neebish was completed in August, 1882. This channel is now 150 feet wide, 17 feet deep. The dredging was done by two dredges owned by John Hickler, working by the hour. The bowlders were picked up by the crane-scow. The amount of material removed was 14,361 cubic yards. The area dredged over was 10,420 square yards. The dredge was at work one thousand two hundred and eighty hours, and the crane-scow three hundred and seventy hours. DREDGING IN LAKE GEORGE. This work was under contract of September 22, 1881, with Charles S. Barker, and was finished in November, 1882, giving a 17-foot channel through Lake George. The final survey and estimate was made in January, 1883, by Assistant Engineer Ripley, the soundings being made through holes cut in the ice; eleven thousand soundings were required. The work was accepted, as completed, in February, 1883, and no estimate is submitted for a further appropriation. SETTING OUT BUOYS. There are fifty-three buoys in Saint Mary's River, which require to be located very accurately (say within 6 feet), in order to get the full benefit of the channel. They are located from intersections given by two observers with theodolites, stationed on shore. For the last year this work was done as part of the improvement. The method is as follows, viz: The azimuth of the site of each buoy has been computed from two or more stations. An observer with theodolite, signalman, and flag, is placed at each of the stations in pairs; the stations being usually intervisible. The observers orient their instruments by pointing at each other, with proper readings. The azimuth to the buoy is then turned off. An assistant in a small boat places a small buoy, called a "marker,” at the intersection of the two azimuths, which is indicated by the proper signals from the observers. This work occupied three assistants and seven men, with the tug Myra, one week. * Appended is a sketch showing the location of the stations used; also tables giving the co-ordinates of the stations, and the azimuths of stations from each other, and to the buoys. The stations are usually cedar posts, surrounded by a pile of stones, with the number of the station cut in the top of the post. The tables were prepared by Mr. Noble, when he was in charge of the work, and it is thought advisable to preserve them in this form for future reference. The number of each buoy and its location are those given in the list of beacons, buoys, and stakes in the eleventh light-house district for the year 1883. HEIGHT OF SURFACE OF WATER IN LAKE SUPERIOR. Tide-gauge observations have been made at Sault Ste. Marie for thir teen years. At first they were made by the United States Lake Survey. Afterwards they were made by the Saint Mary's River Improvement and the data furnished to the United States Lake Survey, which published them up to October, 1881. The observations have all been collected and reduced to the canal datum. The mean for each month has been taken. These means have been plotted in a form of a curve which is given on the following page. The date is the abscissa, and the height of the water surface above the canal datum is the ordinate. The mean yearly curve has been found by taking the mean of all the January means, then of all the February means, and so for each month. *Not printed. These means when plotted give a very symmetrical curve which is shown by the dotted line on the following plot.* It will be seen that the average yearly range in height is 1.2 feet. The line of high water is August and September, and of low water, March and April. Money statement. July 1, 1882, amount available July 1, 1883, amount expended during fiscal year, exclusive of outstanding liabilities July 1, 1882 July 1, 1883, outstanding liabilities.... $74,054 66 $70,597 19 70,929 50 3,125 16 |