The second light has been placed on White Shoal, at the north end of Lake Michigan, and supersedes a lightship which fulfilled all requirements for many years. The shoal is exceptionally dangerous, and the crowded character of the shipping demanded the installation of a more powerful light and fog-signal. The structure is a striking piece of work, comprising a steel cylindrical tower, or shell, lined on the inside with brick and faced externally with terra-cotta--an unusual material for lighthouse construction. The superstructure is built upon a massive concrete pier, about 70 feet square, rising 20 feet above water-level, this being borne in turn upon a heavy stone-filled timber crib laid on a block-stone foundation, the whole being protected thoroughly with riprap. The lantern is of the second flashing order, with the focal plane 125 feet above the lake-level, and the 65,000 candle-power ray is visible twenty-five miles away. The tower is fitted with a duplicate plant of twenty-four horse-power oil-engines and air-compressors, operating an eight-inch whistle; and there is also an electrically-operated submarine bell, the power for which is generated by an independent oil-engine, the bell being operated from the engine-room. This station is equipped also with a compressed air water-supply system and a motor-boat. [Illustration: THE LATEST DEVELOPMENT IN LIGHTHOUSE ENGINEERING. Building the hexagonal tower on Caribou Island, Lake Superior, upon the lines evolved by Lieut.-Col. W. P. Anderson, the chief engineer to the Canadian Lighthouse Department.] Owing to the peculiar prevailing conditions, the provision of adequate beacons upon the Great Lakes is highly expensive. Up to the year 1883 more money had been devoted to the lighting of the shoreline of Lake Michigan than to the illumination of any ocean or gulf in any other State in the country. The total expenditure up to the above year exceeded £470,000, or $2,350,000. The Spectacle Reef light was considered cheap at £75,000, or $375,000; and the Stannard Rock lighthouse, owing to the plant and other facilities being available from the foregoing work, cost £60,000, or $300,000. By the time the “Rock of Ages” tower threw its light, £27,649, or $138,245, had been sunk; and the White Shoals lighthouse absorbed £50,000, or $250,000. The Canadian Government, too, has completed some notable works upon the Great Lakes during recent years. In Lake Erie, in the fairway of passing traffic, is a ledge known as Colchester Reef, on the south-east edge of which a lighthouse, one of the most isolated in Canadian waters, has been placed. The circular stone pier is built in 14 feet of water, and the lighthouse, comprising a two-story dwelling and tower, supports the beacon 60 feet above the lake. The light is a fixed white, of the third dioptric order, visible throughout a circle of fourteen miles radius.