The next summer the new apparatus was got on to the rock and erected safely. The light is of the dioptric type, derived from a series of incandescent burners, giving a total power of 1,200 candles. This part of the installation is the invention of the chief engineer to the Commissioners, Mr. C. W. Scott, and it has proved to be one of the most perfect and economical devices of this type yet submitted to practical operations. The oil is vaporized by being passed through a spraying device under pressure, similar to the forced carburation in automobile practice, and the gas is fed to the Bunsen burners. The lenses, together with their revolving apparatus, weigh 13,440 pounds, and rotate upon a bed of mercury under the fall of a weight of 290 pounds, which descends 40 feet per hour, this being sufficient to secure three complete revolutions per minute. In case the incandescent gas installation should break down from any cause, a four-wick oil-burner is held in reserve, and can be brought into action instantly. The power of the rays thrown from the 1,200 candle-power burners is intensified by the lenses to some 750,000 candle-power, of extremely white brilliancy, recalling the beam thrown by an electric searchlight. The flash, of three-twenty-fifths of a second’s duration, recurs every five seconds, and on a clear night the light is readily distinguishable from a distance of twenty miles, while its reflection in the sky may be observed from a considerably greater distance.
The erection of this lighthouse was not without one humorous incident. While the lantern apparatus was being set in position, a plumber was sent to the rock. He spent one day and night there, a period that proved to be more than enough for him. The murmuring of the waves lost all their musical glamour for him when he was imprisoned on a wild, isolated, wind-and-wave-swept eyrie. He did not get a wink of sleep, and was scared nearly out of his wits. When morning broke, and the men were turned out of their bunks, the plumber expressed his fixed determination to return to the shore at once. His companions laughed at his fears, ridiculed his anxieties, coaxed and upbraided him in turn. It was of no avail. He would not do another stroke of work. Realizing the hopelessness of such a workman, the engineer in charge signalled the mainland for assistance. The steamer could not put out, but the lifeboat, not understanding the import of such an unusual call, made the dangerous pull to the rock, to ascertain what was the matter. When they found that it was to take off a scared workman, their feelings may be imagined. The demoralized plumber was bundled into the lifeboat and rowed back to shore. The blood did not return to his face, nor did he collect his scattered wits, until he planted his two feet firmly on the mainland, when he very vehemently and picturesquely expressed his determination never to accept a job in such a forsaken place again.
The old tower was reduced to the level of its solid base, and converted into an oil-store. The finishing touches were applied to the new tower, and on June 27, 1906, the scintillating and penetrating ray of the present Fastnet was shown for the first time. It is a magnificent light, and, being the latest expression of British lighthouse engineering upon a large scale, compels more than passing interest. The light is fully in keeping with the importance of the spot it marks, and the £84,000, or $420,000, which it cost has been laid out to excellent purpose. The light and fog-signal station is tended by six keepers, four being on the rock simultaneously, and two ashore. The latter constitute the relief, which is made twice a month if the weather permits, the service being one month on the rock, followed by a fortnight on shore. One keeper has day duty, maintaining a lookout for fog and to signal passing ships; two are on duty at night, the one having charge of the light and its operation, while his comrade devotes his attention to signalling ships and watching the weather. When a mist creeps over the light, the fourth keeper is called up to manipulate the explosive fog-signal. The lighthouse, being an important landfall, is a signalling-station for Lloyd’s, and is also fitted with wireless telegraphy, wherewith the movements of outgoing and incoming vessels are reported to the mainland for notification to all parts of the world.
CHAPTER X
LIGHTHOUSES BUILT ON SAND
While the greater number of the most famous sea-lights have been erected upon the solid foundation offered by rock, in one or two instances notable works have been consummated upon sand. The two most remarkable achievements in this particular field of enterprise are the Rothersand lighthouse, off the coast of Germany, in the North Sea, and the Fourteen Foot Bank, in Delaware Bay, U.S.A.
The Rothersand light became necessary owing to the expansion of the German mercantile marine and the development of the ports of the Weser and Elbe. The estuary of the Weser River is hemmed in by shoals and sandbanks, similar to those found at the entrance to Liverpool, London, and New York, rendering navigation extremely hazardous under the most favourable circumstances. Bremerhaven, on the Weser, had been selected as the home port for the North German Lloyd Atlantic liners, but it was threatened with abandonment unless the entrance to the waterway should undergo improvement. It was of no avail to dredge a deep channel through the treacherous ridges of sand, if the general proximity of the shoal were left unmarked. Consequently, in order to secure the interests of Bremerhaven, it was decided by the three border States—Prussia, Oldenburg, and Bremen—to provide a powerful light at this danger-point. The financial problem was solved by the agreement to levy a special tax upon all vessels entering the Weser, to defray the cost of providing the safeguard.
The undertaking was somewhat formidable. The shoal, being of soft sand, was liable to erosion and movement, owing to fluctuating and changing currents. Then, again, the proposed site, some thirty miles from Bremerhaven and about halfway between that port and the island of Heligoland, was exposed to the assaults of the North Sea, where even slight breezes ruffle the water considerably. From the soundings and observations that were made, it was evident that the foundations would have to be carried down to a great depth, and that ordinary systems of construction were quite impracticable. At this juncture the Society Harkort of Duisburg, which had accumulated great experience in subaqueous work, was approached and asked if it would undertake the enterprise at its own risk. This was tantamount to a “no cure, no pay” proposal. If they succeeded, they would be rewarded for their labours; if they failed, they would have to face a heavy loss.
This firm, after careful deliberation, allowed that the work could be accomplished, but in one way only. This was to construct a huge caisson—practically a gigantic barrel of steel—on shore, to launch and tow it to the site, and there to lower it until it rested on the bottom. Then, by a removal of the sand from beneath this caisson, it could be sunk to a great depth, and, the interior being filled with concrete, a huge artificial core of rock would be created, capable of supporting a tower. This system is employed extensively in connection with bridge-building operations, and the firm entertained no doubts concerning its feasibility at Rothersand. The society accordingly prepared its designs, and advanced an estimate for the cost of the work.