Lightships and Lighthouses

by Frederick Arthur Ambrose Talbot

By permission of Messrs. Bullivant & Co., Ltd.

SETTING THE LAST STONE OF THE BEACHY HEAD LIGHTHOUSE.

The base was completed in a single year, and in 1876 the erection of the tower proper was commenced, together with the completion of the approaching stairway leading from the water-level to the base of the structure. The latter, divided into seven stories, rises in the form of a slender cone, tapering from a diameter of 21½ feet at the bottom to 16½ feet at the top beneath the lantern. Some idea of the massive character of the work which was demanded in order to resist the intense fury of the waves may be realized when it is mentioned that the wall at the first and second floors is 5½ feet in thickness, leaving a diameter of 10 feet for the apartment on the first floor, which is devoted to the storage of water, and of 7 feet for that on the second floor, which contains the oil reservoirs for the lamps. The living-rooms have a diameter of 11 feet, this increased space being obtained by reducing the thickness of the wall to 2½ feet. The erection of the superstructure went forward steadily, five years being occupied in carrying the masonry from the base to the lantern gallery, so that in 1881 for the first time powerful warning was given of a danger dreaded, and often unavoidable, from the time when ships first sailed these seas. Fifteen years’ labour and peril on the part of the engineers and their assistants were crowned with success.

Whereas the Ar-men light off Cape Finisterre demanded fifteen years for its completion, the construction of the Beachy Head lighthouse off the South of England coast was completed within a few months. It is true that the conditions were vastly dissimilar, but the Sussex shore is exposed to the full brunt of the south-westerly and south-easterly gales. This lighthouse thrusts its slender lines from the water, its foundations being sunk into the chalk bed of the Channel, 550 feet from the base of the towering white cliffs, which constitute a striking background. This beacon was brought into service in 1902, its construction having occupied about two years. The light formerly was placed on the crown of the precipice behind, but, being then some 285 feet above the water, was far from being satisfactory, as its rays were frequently blotted out by the ruffle of mist which gathers around Beachy Head on the approach of evening.

Indeed, this is one of the great objections to placing a light upon a lofty headland. In such a position it does not serve as an aid, but more often than not as a danger, to navigation, owing to the light being invisible at the time when its assistance is required and sought most urgently. Consequently lighthouse engineers endeavour to set their towers at such a level that the light is not raised more than from 160 to 200 feet above the water. In the case of Beachy Head, a further reason for a new structure was the disintegration of the cliff upon which the light stood, under the terrific poundings of the sea, huge falls of chalk having occurred from time to time, which imperilled the safety of the building.

When the new lighthouse was taken in hand, investigation of the sea-bed revealed an excellent foundation in the dense hard chalk, and accordingly a hole 10 feet deep was excavated out of the solid mass to receive the footings of the building. As the site is submerged to a great depth at high-tide, the first operation was the erection of a circular dam carried to a sufficient height to enable the men to toil within. By this arrangement the working spells were lengthened considerably, labour only being suspended at high-tide. When the sea ebbed below the edge of the dam, the water within was pumped out, leaving a dry clear space for the workmen. Excavation had to be carried out with pickaxe and shovel, blasting not being permitted for fear of shattering and splitting up the mass forming the crust of the sea-bed.

Beside the site a substantial iron staging was erected, and from this point to the top of the cliffs behind a Bullivant cableway was stretched, up and down which the various requirements were carried, together with the workmen. This cableway, designed by Mr. W. T. H. Carrington, M.I.C.E., consulting engineer to Messrs. Bullivant and Co., Ltd., facilitated rapid and economical construction very appreciably. The span was about 600 feet between the erecting stage and the cliff summit, and there were two fixed ropes stretched parallel from point to point. One rope, 6 inches in diameter, had a breaking strain of 120 tons; the second, 5½ inches thick, had a breaking strain of 100 tons. At the seaward end the cables were anchored into the solid chalk. Everything required for the constructional operations was handled by this carrying system, and when it is recalled that some of the blocks for the lower courses weighed from 4½ to 5 tons, it will be recognized that such a method of handling these ungainly loads, with the care that was demanded to preserve the edges and faces from injury, solved an abstruse problem completely.

The base of the tower, the diameter of which is 47 feet, is solid to a height of 48 feet, except for a central circular space for storing drinking water. It was designed by Sir Thomas Matthews, M.I.C.E., the Engineer-in-Chief to the Trinity Brethren, and is a graceful building, the tower rising in a curve which is described as a “concave elliptic frustum.” From the base to the lantern gallery is 123½ feet, and 3,660 tons of Cornish granite were used in its construction. The over-all height to the top of the lantern is 153 feet. The building is provided with eight floors, comprising the living and sleeping quarters for the keepers, storage of oil, and other necessaries. The light, of the dioptric order, is of 83,000 candle-power, and the two white flashes given every fifteen seconds are distinguishable for a distance of seventeen miles, which is the average range of modern British lighthouses.

Although the constructional work was frequently interrupted by rough weather, every advantage was taken of calm periods. While from the point of daring engineering it does not compare with many of the other great lights of the world, yet it certainly ranks as a fine example of the lighthouse builder’s skill. Owing to the elaborate precautions observed, the achievement was not marred by a single fatality, although there were many thrilling moments, the sole result of which, however, was the loss of tools and sections of the plant, which in the majority of cases were recovered when the tide fell. The most serious accident was a crushed toe, which befell one of the masons when a stone was being bedded.

Although the lighthouse is subjected to the full fury of wind and wave, if skilfully erected it will withstand the ravages of both without creating the slightest apprehensions in the engineer’s mind. The stones are prepared so carefully that they fit one another like the proverbial glove, while the cement fills every nook and cranny. Occasionally, however, the cement will succumb to the natural disintegrating forces, and, becoming detached, reveal a point vulnerable to attack. The air within the interstice becomes compressed by the surging water, and thereby the fabric is liable to be shattered. Some years ago one or two of the lighthouses guarding the Great Lakes of North America were found to have become weakened from this cause. A novel remedy was evolved by an ingenious engineer. He provided each tottering lighthouse with an iron overcoat, enveloping it from top to bottom. The metal was not laid directly upon the masonry, but was so placed as to leave about a quarter of an inch between the inner face of the metal and the surface of the masonry. Liquid cement was then admitted under pressure—“grouting” it is called—into this annular space, and penetrating every crack and crevice in the masonry, and adhering both to the metal and the stonework, it practically formed another intermediate jacket, binding the two so firmly together as to make them virtually one. This novel procedure absolutely restored the menaced building to its original homogeneity and rigidity, so that it became as sound as the day on which it was built.