LIGHTHOUSE 



342; 



LIGHTNING 



group flashing light, where two or more flashes 

 are followed by an eclipse of several seconds; 

 fixed lights, and others,. The United States 

 government has arranged a code whereby the 

 number of flashes, exact time of revolution and 

 relative number of red and white flashes of a 

 given signal, are recorded and numbered, and 

 the lighthouse corresponding to any number 

 may be found by the mariner in the Light 

 Lists which he carries with him. These Lists 

 are published by the Lighthouse Board. 



In the earliest lighthouses wood or coal 

 burned in braziers provided illumination, but 

 modern sources of light consist of mineral oils 

 (chiefly petroleum), coal and oil gas, acetylene 

 and electricity. Kerosene is the illuminant used 

 in the majority of United States coast stations, 

 but one of the most powerful lights maintained 

 by the Lighthouse Board is that at Navesink, 

 at the entrance to New York Bay, which con- 

 sists of an electric arc with an estimated candle 

 power of 25,000,000; this apparatus flashes a 

 white signal every five seconds. 



Some Notable Lighthouses. The Eddystone 

 Lighthouse, one of the most famous in the 

 world, stands upon a dangerous reef in the 

 English Channel. It is 132 feet high from 

 high-water level to the focal plane of the lan- 

 tern and is built 

 of stones cut so 

 as to interlock. 

 A light tower of 

 unusual height 

 was constructed 

 at One Fathom 

 Bank, on the 

 Strait of Malacca, 

 in 1908, the light 

 being raised on a 

 superstructure 925 

 feet above the 

 water. The foun- 

 dation was laid on 

 piles, which were 

 driven through 

 the sand to firmer 



material below. It is twelve feet high, 



A ,, weighs four tons, and was 



Among the nota- made in France at a cost of 



blp 1i0-hthrm<!P<3 nn $12,000. This lens is in a 



- son lighthouse in Hawaii, com- 



the North Ameri- pleted in 1917. It revolves on 



a mercury float, and its light, 



can coast are 940,000 candle power, is visi- 



those at Minot's ble twent y- five miles - 

 Ledge, in Massachusetts Bay; Spectacle Reef, 

 in Northern Lake Huron; Tillamook Rock, in 

 the Pacific Ocean, twenty miles south of the 

 Columbia River ; and the great tower at Barne- 



ONE OF THE WORLD'S 

 GREATEST LENSES 



gat, New Jersey, which is equipped with a lens 

 having a bull's-eye in the center eighteen inches 

 in diameter. Were it not for the curvature of 

 the earth's surface, its powerful light, equal to 

 30,000,000 candle power, could be seen by sail- 

 ors 100 miles from shore. The new Kilauea 

 Point Lighthouse, on one of the Hawaiian 

 Islands, is also notable for its lens, which is 

 twelve feet high and weighs four tons. 



Lightships. These are in effect floating light- 

 houses. Vessels equipped with signal lights 

 are stationed at dangerous points off coasts, 

 at approaches to harbors and at other places 

 where lighthouses cannot be built. Ships of 

 the most modern design carry a steel lan- 

 tern mast large enough to contain a ladder 

 by which access is obtained to the lantern. 

 The latter is constructed on the same principle 

 as the illuminating apparatus of a lighthouse. 

 Powerful fog signals are also a part of the 

 equipment. More than forty lightships guard 

 the coasts of the United States; the light ves- 

 sel anchored on the dangerous South shoal, 

 twenty-six miles off Nantucket Island, is far- 

 ther from shore than any other such ship in 

 the' world. Buoys and beacons are also placed 

 in narrow sounds, rivers and estuaries, where 

 the danger to navigation is not great enough 

 to warrant the construction of lighthouses or 

 the anchoring of lightships. 



Lighthouse Service. Practically every na- 

 tion with coast waters maintains a lighthouse 

 service. The United States Lighthouse Board 

 constitutes a bureau of the Department of 

 Commerce. The Canadian service is under the 

 direction of the Department of Marine, and in 

 England the lights are in the care of Trinity 

 House Corporation. The Scottish lights are 

 managed by the Commissioners of Northern 

 Lights, and those of Ireland are cared for by 

 the Corporation for Preserving and Improving 

 the Port of Dublin. The lighthouse board of 

 France, known as the Commission of Phares, 

 is under the direction of the Minister of Pub- 

 lic Works. In Denmark, Austria, Holland, 

 Russia, Sweden and Norway the lighting of 

 the coasts is under the care of the Minister of 

 Marine, and in Belgium the lighthouse service 

 is controlled by the Department of Public 

 Works. B.M.W. 



LIGHT 'NING, a flash of light in the sky 

 caused by electrical discharge between clouds, 

 or between clouds and the earth. Lightning 

 is one of the most mysterious and least under- 

 stood of natural phenomena. Centuries ago 

 the ancient Greeks and Romans felt the mys- 



