Lightships and Lighthouses. Frederick Arthur Ambrose Talbot
with a parabolic reflector. Every morning the lamp is lowered, cleaned, and stored in a shack at the foot of the pyramid, to be lighted and hauled into position at dusk. This is the most economical form of lighthouse which has been devised, the total cost of the installation being only about £2,500, or $12,500, while the maintenance charges are equally low. Lights of this description are employed for the most part in connection with the lighting of waterways, constituting what is known as the “back-light” in a range or group of lights studded along the river to guide the navigator through its twists and shallows, instead of buoying of the channel.
The task of constructing a sea-rock lighthouse is as tedious and protracted an enterprise as one could conceive, because the engineer and his workmen are entirely at the mercy of the weather. Each great work has bristled with its particular difficulties; each has presented its individual problems for solution. Few modern lighthouses, however, have so baffled the engineer and have occupied such a number of years in completion, as the Ar-men light off Cape Finisterre. This tower was commenced in 1867, but so great and so many were the difficulties involved in its erection that the light was not first thrown over the Atlantic from its lantern until 1881.
This light is situated at one of the most dreaded parts of a sinister coast. At this spot a number of granite points thrust themselves at times above the water in an indentation which has received the lugubrious name Bay of the Dead. The title is well deserved, for it is impossible to say how many ships have gone down through fouling these greedy fangs, or how many lives have been lost in its vicinity. The waters around the spot are a seething race of currents, eddies, and whirlpools. It is an ocean graveyard in very truth, and although mariners are only too cognizant of its terrible character, and endeavour to give this corner of the European mainland a wide birth, yet storms and fogs upset the calculations of the most careful navigators.
THE THIMBLE SHOALS LIGHT.
A typical example of the American iron screw pile system. A vessel ran into this beacon and wrecked it; the ruins caught fire, and the keepers only escaped in the nick of time.
As the streams of traffic across the Bay of Biscay grew denser and denser, it became imperative to provide a guardian light at this spot, and the engineers embarked upon their task. They knew well that they were faced with a daring and trying enterprise, and weeks were spent in these troubled waters seeking for the most favourable site. As a result of their elaborate surveys, they decided that the rock of Ar-men offered the only suitable situation; but what a precarious foundation upon which to lift a massive masonry tower! The hump is only 25 feet wide by 50 feet in length; no more than three little pinnacles projected above the sea-level, and at low-tide less than 5 feet of the tough gneiss were exposed. Nor was this the most adverse feature. The rock is in the centre of the bad waters, and is swept from end to end, under all conditions of weather, by the furious swell. Some idea of the prospect confronting the engineers may be gathered from the fact that a whole year was spent in the effort to make one landing to take levels.
When construction was taken in hand the outlook was even more appalling. It was as if the sea recognized that its day of plunder was to draw to a close. The workmen were brought, with all materials and appliances, to the nearest strategical point on the mainland, where a depot was established. Yet in the course of two years the workmen, although they strove day after day to land upon the rock, only succeeded twenty-three times, while during this period only twenty-six hours’ work was accomplished! It is not surprising that, when the men did land, they toiled like Trojans to make the most of the brief interval. The sum of their work in this time was the planting of the lighthouse’s roots in the form of fifty-five circular bars, each 2 inches in diameter and spaced 3¼ feet apart at a depth of about 12 inches in the granite mass. By the end of 1870 the cylindrical foundation had crept a few feet above the highest projection; this plinth was 24 feet in diameter, 18 feet in height, and was solid throughout. A greater diameter was impossible as the wall was brought almost to the edge of the rock.
By dint of great effort this part of the work was completed by the end of 1874, which year, by the way, showed the greatest advance that had been attained in a single twelvemonth. As much of the foundations was completed in this year as had been achieved during the three previous years. Although the heavy gales pounded the structure mercilessly, so well was the masonry laid that it offered quite effective resistance. Upon this plinth was placed the base of the tower. This likewise is 24 feet in diameter, and about 10 feet in height. It is also of massive construction, being solid except for a central cylindrical space which is capable of receiving some 5 tons of coal.
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