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.
At the entrance to Parry Sound, on a convenient site offered by the solid granite mass of Red Rock, a new lighthouse was constructed in 1911. This was the third beacon placed at this point, the two previous lights dating from 1870 and 1881 respectively. It is a particularly bad spot, since the waters of Georgian Bay have a free run, so that the rock experiences the full hammering of the sea. The beacon comprises a reinforced concrete building, nearly elliptical in section, supported upon a heavy stone foundation, which is encased in steel, and which is 12 feet high. The tower has a height of 57 feet, bringing the occulting flash of twelve seconds, with an eclipse of four seconds, 60 feet above the water. This station is also equipped with a powerful diaphone. The keepers of this light experience exciting times, as in a furious gale, such as the lakes only can produce, the waves frequently crash over the building.
Another fine light in the stretch of these waters under Canadian jurisdiction is found about halfway across Lake Superior, where Caribou Island thrusts its scrub-clothed hump above the water, almost directly in the path of the vessels running between Sault Ste. Marie and Sarnia. This magnificent structure, placed on a small islet lying off the main island, is built in ferro-concrete, in accordance with Lieutenant-Colonel Anderson’s latest ideas, and was opened for service in 1912. It is of hexagonal shape, with six flying buttresses, and the focal plane is brought 99 feet above the water-level, so that the white flash of half a second may be seen all round from a distance of fifteen miles.
The steamship lanes across the Great Lakes are now well lighted. Canada alone maintains over 460 lights of all descriptions throughout its waters between the eastern extremity of Lake Ontario and the head of Lake Superior at Port Arthur. The United States authorities watch over 694 attended and unattended aids to navigation in the same seas, of which total 152 are scattered around the coastline of Lake Michigan. The mariner in these fresh-water oceans, consequently, has a round thousand lights to guide him on his way, and the number is being steadily increased to keep pace with the growth of the traffic, so that these seas may become regarded as the safest and best protected in the world.