LIGHTED BUOYS Pintsch's oil-gas was first used for a light carried on a buoy in 1878. An automatic occulter, worked by the gas passing from the reservoir to the burner, was introduced in 1883. The majority of buoy lights lit by oil-gas are fitted with multiple-jet or Argand burners, but incandescent mantles are also employed. Ordinary oil-gas has been largely superseded by other forms of gas illumina tion (see p. 96). Gas buoy-lights are usually provided with suffi cient storage capacity to run the light unattended for three months or longer. The lanterns used for all forms of buoy lighting are self-contained with cylindrical dioptric lenses of fixed-light section usually 150 to 375 mm. diameter. Some of the largest types of gas buoy in use have an elevation from water level to the focal plane of over 26 ft., and a beam intensity of more than 1,000 candle power. One buoy placed at the entrance to the Gironde in 1907, has an elevation to the focal plane of 34 feet. Spar buoys may be adopted for situation where strong tides or currents prevail.
Acetylene Gas Buoys.—Although some experimental work was done as early as 1896, acetylene gas was first regularly used for buoy lighting early in the 20th century when automatic water to-carbide generators were employed in Canada for producing the gas, the generators being placed in the body of the buoy. This sys
tem never gave entirely satisfactory results and its use is attended by danger of explosion. It has almost everywhere been superseded by the dissolved acetylene system first applied to buoy lighting in Sweden. The normal acetylene buoy equipment maintains the light without recharging up to 1 2 months (fig. 15).
Electric Buoys.—Buoys have been fitted with electric light both fixed and occulting. Six spar buoys were laid down in the Gedney channel, New York Lower Bay, in 1888. The wear and rear of the cables, by which current was supplied from a shore station, caused considerable trouble and expense, and the lights were replaced by gas-lighted apparatus in 1904. Electric buoys were also used exten sively in Germany early in the present century; but in 1929, very few, if any, examples of this method of buoy lighting remain in service.
Bell andWhistling Buoys.—Bells or whistles are frequently fitted to gas buoys as well as to unlighted marking buoys. An acetylene lighted whistle-buoy is illustrated in fig. 15. Submarine bells have also been fitted to buoys but their functioning in such positions is unreliable.