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362 APPENDIX. The project was modified in 1873, so as to further improve the mid- channel to a depth of 16 feet, and width of 200 feet, This-modification was completed in 1874. Improvements are now in progress by which the depth will be increased to 18 feet. : nee 4 8ST. MARY'S FALLS SHIP CANAL This canal, which overcomes the rapids in the St. Mary River, con- necting the water of Lakes Huron and Superior, is situated in the State of Michigan, and was first projected in 1837, The canal was not, how- ever, commenced until 4th June, 1853, and the first boat passed through the old canal on the 18th June, 1855. Cost of old Canal to 14th May, 1885, $999,802.46. In 1870 the enlargement of the canal was commenced, and it was opened to navigation on Ist September, 1881, but not com- pleted until 1882, up to which time the cost of enlargement had been $2,150,000. : : ~The length of the canal is about 7,000 feet. The width varies; the least width is atthe swing bridge, or movable dam, 108 feet, the depth of water from 154 to 16 feet. The lock is 515 feet long between gates, 80 feet wide in chamber, and 60 feet wide at the gates, with 16 feet of water during mean low water; total lift varies from 16% to 18 feet. The gates and capstans are operated by machinery; the power is produced 7. 7 turbine wheels, which also furnishes power to run the electric ights. oS PoE I,ockK.--The Poe lock upon the site of the old State locks has a length of 800 feet between gates, a width of 100 feet throughout, a depth of 21 feet on the miter sills, and a lift of 18 feet. The canal is deepened to correspond. « Sault Ste. Marie (Canadian) Canal.--This canal is a straight cut through red sandstone rock ,967 feet (about 1% miles) long from end to end of upper and lower piers, and its width is 150 eet at the water surface and 141 feet 8 inches at the bottom. The approaches to the canal are channels dredged through bowlder shoals; the upper approach being at least 250 feet wide with 17:to 19 feeth depths, and the lower approach, since 1902, being at least 500 feet wide with 21 feet depth. A masonry lock is located near the east or lower end of the canal, 900 feet long by 60 feet es wide, and with a low-level depth of 20 feet 3 inches; the lift is about 20 feet; the gates and culvert : valves are operated by electricity. a GREATEST DEPTH OF WATER IN THE LAKES. , Lax Supzrior.--The greatest depth as appears from the Lake Sur- vey is 168 fathoms, at a point 53 miles N. N. E.4E. from Manitou Island light, and 61 miles E. + S. from Passage Island light. | _ Lake Micuigan.--The greatest depth is 145 fathoms, at a point 264 miles S. W. by W. + W. from Point Betsey light, and §. E. by E. 3 E. 334 miles from Sturgeon Bay Ship-canal light. | _Laxe Huron.--The greatest depth is 125 fathoms, at a point 264 miles S. S. W. 3 W. from Cove Island light, and 58 miles E. ¢ S. from fe Bay Island light. . : AKE Hriz.--The greatest depth is 35 fathoms, at a point 64 miles S. E. 3 E. from Long Point light, and N. by E. 4 E. 244 ils hon the -- hes Erie. so | - , JAKE UNTARIO.--Lhe greatest depth is 123 fathoms, at a point 28 miles N. E. by E. ¢ E. from the pierhead light at Charlotte, aa N. N. W.7 W. 154 miles from the main light at Big Sodus, :