. CURVE, LAKE SUPERIOR ns taken "above the Locks "at lls Canal, Mich. he elevation of the surface of the Lake e mean elevation for each month is 5.87ft above sea level (mean lide at th t for the fiscal year ending June 30, 188 Lieut. Col. Corps of Engrs. Eng 55 3 1895. 1896. 1897. 1898. Plane of Reference (H.Wof 1888)=58434 Ft above mean tide of N.. ww NA क 3 फ ANNUAL WATER LEVEL CURVE AT SAND BEACH, LAKE HURON reduced from monthly means of Noon readings. Transmitted with my annual report for the fiscal year ending June 30th. 1898. J.Kyclecter Lieut. Col. Corps of Engrs: Eng 55 3 123456 6 6789 ། It is of interest to compare the values of declination and dip obtained this year with those obtained a number of years ago at some of the places. In Professional Papers, Corps of Engineers, United States Army, Appendix IV, pages 909 and 910, are given the determinations of declination and dip made in 1860 at Mackinac Island, Northport, South Manitou, and Beaver Island, at which places they were also determined this year. The declinations observed in 1860 were with suspended collimator magnets. The annual change of declination as derived from the mean of the four stations is 4.9', increasing westerly, decreasing easterly. The average annual decrease of dip is 0.8'. The comparison of values is as follows: Comparisons of declinations, 1860–1897. SUSPENDED MAGNETS. In the vicinity of many of the places observed at this year declinations were obtained years ago with compass needles. They were needles on transits working on pivots, and do not give results comparable in accuracy with those from suspended magnets. A comparison is given below of these results with the ones obtained this year. A few results obtained in 1895 and 1896 are included for completeness. Comparison of declinations. The following table shows the monthly means of water levels, as derived from daily observations of guages at Sand Beach, Mich., on Lake Huron, and at the head of the St. Marys Falls Canal, Sault Ste. Marie, Mich. Monthly means of water level for Sand Beach and Sault Ste. Marie, expressed in feet, below the plane of reference adopted in 1876. Station. 1897. 1898. July. Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May. June. Sand Beach 3.95 3.94 4.20 4.55 4.67 4.97 5.12 5.06 4.83 4.34 4.22 4.06 3.80 3.96 3.72 3.53 3.12 |