By permission of Messrs. Siemens Bros. & Co., Ltd.
THE 43,000,000 CANDLE-POWER BEAMS THROWN FROM THE HELIGOLAND LIGHTHOUSE.
Being projected from a height of 272 feet above the sea, the beacon has a range of 23 miles, and on a clear night the rays are seen from Büsun, 35 miles away.
Frontispiece.
CONQUESTS OF SCIENCE
LIGHTSHIPS AND
LIGHTHOUSES
BY
FREDERICK A. TALBOT
AUTHOR OF
“MOVING PICTURES,” “RAILWAY CONQUEST OF THE WORLD,”
“THE STEAMSHIP CONQUEST OF THE WORLD,” ETC.
Romances innumerable have been woven around the flaming guardians of the coast, but it is doubtful whether any purely imaginative work is so fascinating and absorbing as the plain unvarnished narrative of how some famous lightship or lighthouse has been brought into existence. And the story of construction is equalled in every way by that relating to the operation and maintenance of the light, against all odds, for the guidance of those who have business upon the ocean.
This volume is not a history of lightships and lighthouses; neither is it a technical treatise. Rather my object has been to relate how the difficulties, peculiar and prodigious, have been overcome by the builders in their efforts to mark some terrible danger-spots, both on the mainland and isolated sea-rocks.
While the lines of the lightship and lighthouse are familiar to all, popular knowledge concerning the internal apparatus of the building or ship is somewhat hazy. Therefore I have explained, with technicalities simplified as much as possible, the equipment of the tower and vessel, and the methods whereby both visual and audible warnings are given. The very latest developments in this field of engineering and science are incorporated, so as to render the subject as comprehensive as possible within the limits of a single volume.
In the compilation of this book I have received the heartiest assistance from those who are prominently associated with the work of providing adequate aids to navigation, and am particularly indebted to the engineers to the Commissioners of Northern Lights, Messrs. D. and C. Stevenson; Lieutenant-Colonel William P. Anderson, the Engineer-in-Chief to the Lighthouse Department of the Canadian Government; the various officials of the Lighthouse Board of the United States of America; the Engineer-in-Chief to the French Service des Phares; the lighthouse authorities of New South Wales and New Zealand; Mr. Gustaf Dalén and his assistants; Messrs. Chance Brothers and Company, Limited, of Birmingham; Messrs. Edmondsons, Limited, of Dublin; Samuel Strain, Esq., the Director of the Lighthouse Literature Mission, Belfast; the Scientific American, and the Syren and Shipping, etc.
FREDERICK A. TALBOT.
June, 1913.
THE ORIGIN OF THE LIGHTHOUSE
The mariner, in pursuit of his daily business, is exposed to dangers innumerable. In mid-ocean, for the most part, he need not fear them particularly, because he has plenty of sea-room in which to navigate his ship, and in case of thick fog he can ease up until this dreaded enemy lifts or disperses. But in crowded coastal waters his position is often precarious, for he may be menaced by lurking shoals or hidden reefs, which betray little or no indication of their whereabouts, and which may be crossed with apparent safety. If the ship blunders on in ignorance, it is brought up with a thud as it buries its nose in the sucking sand, or gives a mighty shiver as it scrapes over the rocky teeth, perhaps to be clasped as in a vice, or to be battered and broken so fearfully that, when at last it tears itself free and slips off into deep water, it can only founder immediately. Here, if fog blots out the scene, the ship is in danger of being lured to certain destruction by currents and other natural forces, since the captain is condemned to a helplessness as complete as of a blind man in a busy street.
It is not surprising, then, that the captain, as he approaches or wanders along a tortuous shoreline, scans the waters eagerly for a glimpse of the guardian monitor, which, as he knows from his reckonings and chart, should come within sight to guide him on his way. The danger-signal may be one of many kinds—a misty, star-like glimmer thrown from a buoy dancing on the waves, the radiant orb from a lightship bobbing up and down and swinging rhythmically to and fro, a fixed flare-light, or dazzling, spoke-like rays revolving across the sky. If sight be impossible owing to fog, he must depend upon his ear for the measured tolling of a bell, the shriek of a whistle, the deep blare of a siren, or the sharp report of an explosive. When he has picked up one or other of these warnings, he feels more at ease, and proceeds upon his way, eyes and ears keenly strained for warning of the next danger ahead.
The lighthouse is the greatest blessing that has been bestowed upon navigation. It renders advance through the waters at night as safe and as simple as in the brilliancy of the midday sun. But for these beacons the safe movement of ships at night or during fog along the crowded steamship highways which surround the serrated shores of the five continents would be impossible. It is only natural, therefore, that the various nations of the world should strenuously endeavour to light their coasts so adequately that the ship may proceed at night as safely and as comfortably as a man may walk down an illuminated city thoroughfare.
Whence came the idea of lighting the coastline with flaring beacons? It is impossible to say. They have been handed down to modern civilization through the mists of time. The first authentic lighthouse was Sigeum, on the Hellespont, which undoubtedly antedates the famous Pharos of Alexandria. The latter was a massive square tower, 400 feet high, and was known as one of the Seven Wonders of the World. It was built about 331 B.C. The warning light was emitted from a huge wood fire, which was kept burning at the summit continuously during the night; the illumination is stated to have been visible for a distance of forty miles, but modern knowledge disputes this range. The precise design of this wonderful tower is unknown, but it must have been a huge structure, inasmuch as it is computed to have cost the equivalent in modern money of over £200,000, or $1,000,000.
For sixteen hundred years it guided the navigators among the waters from which it reared its smoking crest, and then it disappeared. How, no one knows, although it is surmised that it was razed by an earthquake; but, although it was swept from sight, its memory has been preserved, and the French, Italian, and Spanish nations use its name in connection with the lighthouse, which in France is called phare; in the other two countries mentioned, faro.
The Romans in their conquest of Gaul and Britain brought the lighthouse with them, and several remains of their efforts in this direction are to be found in England, notably the pharos at Dover.
In all probability, however, the lighthouse in its most primitive form is at least as old as the earliest books of the Bible. Undoubtedly it sprang from the practice of guiding the incoming boatman to his home by means of a blazing bonfire set up in a conspicuous position near by. Such a guide is a perfectly obvious device, which even to-day is practised by certain savage tribes.
When the Phœnicians traded in tin with the ancient Britons of Cornwall, their boats continually traversed the rough waters washing the western coasts of Spain, where, for the safer passage of their sailors, doubtless, they erected beacons upon prominent headlands. The oldest lighthouse in the world to-day, which in some quarters is held to be of Phœnician origin, is that at Corunna, a few miles north of Cape Finisterre. Other authorities maintain that it was built during the reign of the Roman Emperor Trajan. In 1634 it was reconstructed, and is still in existence.
At the mouth of the Gironde is another highly interesting link with past efforts and triumphs in lighthouse engineering. The Gironde River empties itself into the Bay of Biscay through a wide estuary, in the centre of which is a bunch of rocks offering a terrible menace to vessels. This situation achieved an unenviable reputation in the days when ships first ventured out to sea. Being exposed to the broad Atlantic, it receives the full force of the gales which rage in the Bay of Biscay, and which make of the Gironde River estuary a fearful trap. The trading town of Bordeaux suffered severely from the ill fame attached to the mouth of the waterway upon which it was dependent, for both the sea and the roads exacted a heavy toll among the ships which traded with the famous wine capital of Gascony. How many fine vessels struck the rocks of Cordouan and went to pieces within sight of land, history does not record, but the casualties became so numerous that at last the firms trading with Bordeaux refused to venture into the Gironde unless a light were placed on the reef to guide their captains. Alarmed at the prospect of losing their remunerative traffic, the citizens of Bordeaux built a tower upon the deadly reef, with a beacon which they kept stoked with wood, four men being reserved for its service. In return the authorities exacted a tax from each vessel arriving and leaving the port, in order to defray the expense thus incurred. Probably from this action originated the custom of lighthouse dues.
This bonfire served its purposes until the Black Prince brought Gascony under his power. He demolished the primitive beacon, and erected in its place another tower, 40 feet high, on which the chauffer was placed, a hermit being entrusted with the maintenance of the light at night. Near the lighthouse—if such it can be called—a chapel was built, around which a few fishermen erected their dwellings. When the hermit died, no one offered to take his place. The beacon went untended, the fishermen departed, and the reef once more was allowed to claim its victims from shipping venturing into the estuary.
In 1584 an eminent French architect, Louis de Foix, secured the requisite concession to build a new structure. He evolved the fantastic idea of a single building which should comprise a beacon, a church and a royal residence in one. For nearly twenty-seven years he laboured upon the rock, exposed to the elements, before he (or rather his successor) was able to throw the welcome warning rays from the summit of his creation. This was certainly the most remarkable lighthouse that has ever been set up. It was richly decorated and artistically embellished, and the tower was in reality a series of galleries rising tier upon tier. At the base was a circular stone platform, 134 feet in diameter, flanked by an elegant parapet surrounding the light-keepers’ abode. This lower structure was intended to form a kind of breakwater which should protect the main building from the force of the waves. On the first floor was a magnificent entrance hall, leading to the King’s apartment, a salon finely decorated with pillars and mural sculptures. Above was a beautiful chapel with a lofty roof supported by carved Corinthian columns. Finally came the beacon, which at that date was about 100 feet above the sea-level.
Access to the successive floors was provided by a beautiful spiral staircase, the newels of which were flanked by busts of the two French Kings, Henry III. and Henry IV., and of the designer de Foix. The architect died not long before his work was completed, but the directions he left behind him were so explicit that no difficulty was experienced in consummating his ideas, and the Tour de Cordouan shed its beneficial light for the first time over the waters of the Bay of Biscay in 1611. So strongly was the building founded that it has defied the attacks of Nature to this day, although it did not escape those of the vandals of the French Revolution, who penetrated the tower, where the busts of the two Henrys at once excited their passion. The symbols of monarchy were promptly hurled to the floor, and other damage was inflicted. When order was restored, the busts were replaced, and all the carvings which had suffered mutilation from mob law were restored. At the same time, in accordance with the spirit of progress, the tower was modified to bring it into line with modern lighting principles; it was extended to a height of 197 feet, and was crowned with an up-to-date light, visible twenty-seven miles out to sea. For more than three centuries it has fulfilled its designed purpose, and still ranks as the most magnificent lighthouse that ever has been built. Its cost is not recorded, but it must necessarily have been enormous.
In Great Britain the seafarer’s warning light followed the lines of those in vogue upon the older part of the Continent, consisting chiefly of wood and coal fires mounted on conspicuous lofty points around the coast. These braziers were maintained both by public and by private enterprise. Patents were granted to certain individuals for the upkeep of beacons in England and Scotland, and from time to time the holders of these rights came into conflict with the public authority which was created subsequently for the maintenance of various aids to navigation around the coasts. In England these monopolies were not extinguished until 1836, when the Brethren of Trinity House were empowered, by special Act of Parliament, to purchase the lights which had been provided both by the Crown and by private interests, so as to bring the control under one corporation.
Photo by permission of Messrs. Bullivant & Co., Ltd.
HOW THE BEACHY HEAD LIGHTHOUSE WAS BUILT.
To facilitate erection a cableway was stretched between the top of Beachy Head and a staging placed beside the site of the tower in the water. A stone is being sent down.
The chauffer, however, was an unsatisfactory as well as an expensive type of beacon. Some of these grates consumed as many as 400 tons of coal per annum—more than a ton of coal per night—in addition to vast quantities of wood. Being completely exposed, they were subject to the caprices of the wind. When a gale blew off the land, the light on the sea side was of great relative brilliancy; but when off the water, the side of the fire facing the sea would be quite black, whereas on the landward side the fire bars were almost melting under the fierce heat generated by the intense draughts. This was the greater drawback, because it was, of course, precisely when the wind was making a lee shore below the beacon that the more brilliant light was required.
When the Pilgrim Fathers made their historic trek to the United States, they took Old World ideas with them. The first light provided on the North American continent was at Point Allerton, the most prominent headland near the entrance to Boston Harbour, where 400 boatloads of stone were devoted to the erection of a tower capped with a large basket of iron in which “fier-bales of pitch and ocum” were burned. This beacon served the purpose of guiding navigators into and out of Boston Harbour for several years.
When, however, the shortcomings of the exposed fire were realized, attempts were made to evolve a lighting system, which does in reality constitute the foundation of modern practice. But the beacon fire held its own for many years after the new principle came into vogue, the last coal fire in England being the Flat Holme Light, in the Bristol Channel, which was not superseded until 1822.
In Scotland the coal fire survived until 1816, one of the most important of these beacons being that on the Isle of May, in the Firth of Forth, which fulfilled its function for 181 years. This was a lofty tower, erected in 1636, on which a primitive type of pulley was installed for the purpose of raising the fuel to the level of the brazier, while three men were deputed to the task of stoking the fire. It was one of the private erections, and the owner of the Isle of May, the Duke of Portland, in return for maintaining the light, was allowed to exact a toll from passing vessels. When the welfare of the Scottish aids to navigation was placed under the control of the Commissioners of Northern Lighthouses, this body, realizing the importance of the position, wished to erect upon the island a commanding lighthouse illuminated with oil lamps; but it was necessary first to buy out the owner’s rights, and an Act of Parliament was passed authorizing this action, together with the purchase of the island and the right to levy tolls, at an expenditure of £60,000, or $300,000. In 1816 the coal fire was finally extinguished.
Photo by permission of Messrs. Bullivant & Co., Ltd.
WORKMEN RETURNING BY THE AERIAL CABLEWAY TO THE TOP OF BEACHY HEAD.
The English lights are maintained by the Brethren of Trinity House, and their cost is defrayed by passing shipping. This corporation received its first charter during the reign of Henry VIII. Trinity House, as it is called colloquially, also possesses certain powers over the Commissioners of Northern Lights and the Commissioners of Irish Lights, and is itself under the sway, in regard to certain powers, such as the levy of light dues, of the Board of Trade. This system of compelling shipowners to maintain the coast lights is somewhat anomalous; it possesses many drawbacks, and has provoked quaint situations at times. Thus, when the Mohegan and the Paris were wrecked on the Manacles within the space of a few months, the outcry for better lighting of this part of the Devon and Cornish coasts was loud and bitter. The shipowners clamoured for more protection, but at the same time, knowing that they would have to foot the bill, maintained that further lighting was unnecessary.
The British Isles might very well emulate the example of the United States, France, Canada, and other countries, which regard coast lighting as a work of humanity, for the benefit of one and all, and so defray the cost out of the Government revenues. Some years ago, when an International Conference was held to discuss this question, some of the representatives suggested that those nations which give their lighthouse services free to the world should distinguish against British shipping, and levy light-dues upon British ships, with a view to compelling the abolition of the tax upon foreign vessels visiting British ports. Fortunately, the threat was not carried into execution.
The design and construction of lighthouses have developed into a highly specialized branch of engineering. Among the many illustrious names associated with this phase of enterprise—de Foix, Rudyerd, Smeaton, Walker, Douglass, Alexander, and Ribière—the Stevenson family stands pre-eminent. Ever since the maintenance of the Scottish coast lights was handed over to the Northern Commissioners, the engineering chair has remained in the hands of this family, the names of whose members are identified with many lights that have become famous throughout the world for their daring nature, design, and construction. Moreover, the family’s contributions to the science of this privileged craft have been of incalculable value. Robert Louis Stevenson has written a fascinating story around their exploits in “A Family of Engineers.”
It was at first intended that the great author himself should follow in the footsteps of his forbears. He completed his apprenticeship at the drawing-table under his father and uncle, and became initiated into the mysteries of the craft. At the outset he apparently had visions of becoming numbered among those of his family who had achieved eminence in lighthouse construction, and he often accompanied his father or uncle on their periodical rounds of inspection. Probably the rough and tumble life in a small tender among the wild seas of Scotland, the excitement of landing upon dangerous rocks, the aspect of loneliness revealed by acquaintance with the keepers, and the following of the growth of a new tower from its foundations, stirred his imagination, so that the dormant literary instinct, which, like that of engineering, he had inherited, became fired. Mathematical formulæ, figures, and drawings, wrestled for a time with imagination and letters, but the call of the literary heritage proved triumphant, and, unlike his grandfather, who combined literature with lighthouse construction, and who, indeed, was a polished author, as his stirring story of the “Bell Rock Lighthouse” conclusively shows, he finally threw in his lot with letters.
The fact that for more than a century one family has held the exacting position of chief engineer to the Northern Commissioners, and has been responsible for the lights around Scotland’s troublous coasts, is unique in the annals of engineering. Each generation has been identified with some notable enterprise in this field. Thomas Smith, the father-in-law of Robert Stevenson, founded the service, and was the first engineer to the Commissioners. Robert Stevenson assumed his mantle and produced the “Bell Rock.” His son, Alan Stevenson, was the creator of the “Skerryvore.” The next in the chain, David Stevenson, built the “North Unst.” David and Thomas Stevenson, who followed, contributed the “Dhu-Heartach” and the “Chicken Rock” lights; while the present generation, David and Charles, have erected such works as “Rattray Briggs,” “Sule Skerry,” and the Flannen Islands lighthouses. In addition, the latter have developed lighthouse engineering in many novel directions, such as the unattended Otter Rock lightship, the unattended Guernsey lighthouse, and the automatic, acetylene, fog-signal gun, which are described elsewhere in this volume.
Some forty years ago the Stevensons also drew up the scheme and designed the first lighthouses for guarding the coasts of Japan. The essential optical apparatus and other fittings were built and temporarily erected in England, then dismantled and shipped to the East, to be set up in their designed places. The Japanese did not fail to manifest their characteristic trait in connection with lighthouses as with other branches of engineering. The structures produced by the Scottish engineers fulfilled the requirements so perfectly, and were such excellent models, as to be considered a first-class foundation for the Japanese lighthouse service. The native engineers took these lights as their pattern, and, unaided, extended their coast lighting system upon the lines laid down by the Stevensons. Since that date Japan has never gone outside her own borders for assistance in lighthouse engineering.
BUILDING A LIGHTHOUSE
Obviously, the task of erecting a lighthouse varies considerably with the situation. On the mainland construction is straightforward, and offers little more difficulty than the building of a house. The work assumes its most romantic and fascinating form when it is associated with a small rocky islet out to sea, such as the Eddystone, Skerryvore, or Minot’s Ledge; or with a treacherous, exposed stretch of sand, such as that upon which the Rothersand light is raised. Under such conditions the operation is truly herculean, and the ingenuity and resource of the engineer are taxed to a superlative degree; then he is pitted against Nature in her most awful guise. Wind and wave, moreover, are such formidable and relentless antagonists that for the most momentary failure of vigilance and care the full penalty is exacted. Then there are the fiercely scurrying currents, tides, breakers, and surf, against which battle must be waged, with the odds so overwhelmingly ranged against frail human endeavour that advance can only be made by inches. The lighthouse engineer must possess the patience of a Job, the tenacity of a limpet, a determination which cannot be measured, and a perseverance which defies galling delays and repeated rebuffs. Perils of an extreme character beset him on every hand; thrilling escape and sensational incident are inseparable from his calling.
The first step is the survey of the site, the determination of the character of the rock and of its general configuration, and the takings of levels and measurements for the foundations. When the rugged hump is only a few feet in diameter little latitude is afforded the engineer for selection, but in instances where the islet is of appreciable area some little time may be occupied in deciding just where the structure shall be placed. It seems a simple enough task to determine; one capable of solution within a few minutes, and so for the most part it is—not from choice, but necessity—when once the surface of the rock is gained. The paramount difficulty is to secure a landing upon the site. The islet is certain to be the centre of madly surging currents, eddies, and surf, demanding wary approach in a small boat, while the search for a suitable point upon which to plant a foot is invariably perplexing. Somehow, the majority of these bleak, wave-swept rocks have only one little place where a landing may be made, and that only at certain infrequent periods, the discovery of which in the first instance often taxes the engineer sorely.
Often weeks will be expended in reconnoitring the position, awaiting a favourable wind and a placid sea. Time to the surveyor must be no object. He is the sport of the elements, and he must curb his impatience. To do otherwise is to court disaster. The actual operations on the rock may only occupy twenty minutes or so, but the task of landing is equalled by that of getting off again—the latter frequently a more hazardous job than the former.
The west coast of Scotland is dreaded, if such a term may be used, by the engineer, because the survey inevitably is associated with bitter disappointments and maddening delays owing to the caprices of the ocean. This is not surprising when it is remembered that this coastline is of a cruel, forbidding character and is exposed to the full reach of the Atlantic, with its puzzling swell and vicious currents. The same applies to the west coast of Ireland and the open parts of the South of England. The Casquets, off the coast of Alderney, are particularly difficult of approach, as they are washed on all sides by wild races of water. There is only one little cove where a landing may be effected by stepping directly from a boat, and this place can be approached only in the calmest weather and when the wind is blowing in a certain direction. On one occasion, when I had received permission to visit the lighthouse, I frittered away three weeks in Alderney awaiting a favourable opportunity to go out, and then gave up the attempt in disgust. As it happened, another month elapsed before the rock was approachable to make the relief.
When the United States Lighthouse Board sanctioned the construction of the Tillamook lighthouse on the rock of that name, off the Oregon coast, the engineer in charge of the survey was compelled to wait six months before he could venture to approach the island. In this instance, however, his time was not wasted entirely, as there were many preparations to be completed on the mainland to facilitate construction when it should be commenced. Early in June, 1879, the weather moderated, and the Pacific assumed an aspect in keeping with its name. Stimulated by the prospect of carrying out his appointed task, the engineer pushed off in a boat, but, to his chagrin, when he drew near the rock he found the prospects of landing to be hopeless. He cruised about, reconnoitring generally from the water, and then returned to shore somewhat disgusted.
A fortnight later he was instructed to take up his position at Astoria, to keep a sharp eye on the weather, to take the first chance that presented itself of gaining the rock, and not to return to headquarters until he had made a landing. He fretted and fumed day after day, and at last pushed off with a gang of men when the sea where it lapped the beach of the mainland was as smooth as a lake; but as they drew near the Tillamook it was the same old story. A treacherous swell was running, the waves were curling wickedly and fussily around the islet; but the engineer had made up his mind that he would be balked no longer, so the boat was pulled in warily, in the face of terrible risk, and two sailors were ordered to get ashore by hook or by crook. The boat swung to and fro in the swell. Time after time it was carried forward to the landing spot by a wave, and then, just as the men were ready to jump, the receding waters would throw it back. At last, as it swung by the spot, the two men gave a leap and landed safely. The next proceeding was to pass instruments ashore, but the swell, as if incensed at the partial success achieved, grew more boisterous, and the boat had to back away from the rock. The men who had landed, and who had not moved a yard from the spot they had gained, became frightened at this manœuvre, and, fearing that they might be marooned, jumped into the sea, and were pulled into the boat by means of their life-lines, without having accomplished a stroke.
By permission of the Lighthouse Literature Mission.
THE SANGANEB REEF LIGHTHOUSE IN THE RED SEA.
It indicates a treacherous coral reef, 703 miles from Suez. It is an iron tower 180 feet high, with a white flashing light having a range of 19 miles.
The engineer chafed under these disappointments, and himself determined to incur the risk of landing at all hazards. With his tape-line in his pocket, he set out once more a few days later, and in a surf-boat pulled steadily into the froth and foam around the rock; while the men sawed to and fro the landing-place, he crouched in the bow, watching his opportunity. Presently, the boat steadying itself for a moment, he made a spring and reached the rock. He could not get his instruments ashore, so without loss of time he ran his line from point to point as rapidly as he could, jotted down hurried notes, and, when the swell was growing restive again, hailed the boat, and at a favourable moment, as it manœuvred round, jumped into it.
The details he had secured, though hastily prepared, were sufficient for the purpose. His report was considered and the character of the beacon decided. There was some discussion as to the most favourable situation for the light upon the rock, so a more detailed survey was demanded to settle this problem. This task was entrusted to an Englishman, Mr. John R. Trewavas, who was familiar with work under such conditions. He was a master-mason of Portland and had been engaged upon the construction of the Wolf Rock, one of the most notable and difficult works of its kind in the history of lighthouse engineering.
He pushed off to the rock on September 18, 1879, in a surf-boat, only to find the usual state of things prevailing. The boat was run in, and, emulating the first engineer’s feat, he cleared the water and landed on the steep, rocky slope; but it was wet and slippery, and his feet played him false. He stumbled, and stooped to regain his balance, but just then a roller curled in, snatched him up and threw him into the whirlpool of currents. Life-lines were thrown, and the surf-boat struggled desperately to get near him, but he was dragged down by the undertow and never seen again. This fatality scared his companions, who returned hastily to the mainland. The recital of their dramatic story stirred the public to such a pitch that the authorities were frantically urged to abandon the project of lighting the Tillamook.
Mr. David Stevenson related to me an exciting twenty minutes which befell him and his brother while surveying a rock off the west coast of Scotland. They had been waiting patiently for a favourable moment to effect a landing, and when at last it appeared they drew in and clambered ashore. But they could not advance another inch. The rock was jagged and broken, while its surface was as slippery as ice owing to a thick covering of slimy seaweed whereon boots could not possibly secure a hold. Having gained the rock with so much difficulty, they were not going away empty-handed. As they could not stand in their boots, they promptly removed them, and, taking their line and levels, picked their way gingerly over the jagged, slippery surface in their stockinged feet. Movement certainly was exceedingly uncomfortable, because their toes displayed an uncanny readiness to find every needle-point on the islet; but the wool of their footwear enabled them to obtain a firm grip upon the treacherous surface, without the risk of being upset and having a limb battered or broken in the process. Twenty minutes were spent in making investigations under these disconcerting conditions, but the time was adequate to provide all the details required. When they had completed the survey and had regained their boat—a matter of no little difficulty in the circumstances—their feet bore sad traces of the ordeal through which they had passed. However, their one concern was the completion of the survey; that had been made successfully and was well worth the toll exacted in the form of physical discomfort.
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THE ALCATRAZ LIGHTHOUSE |
THE ALCATRAZ |
This tower off the Californian coast is one of the latest works of the American Lighthouse Department. It has a range of 21 miles.
As a rule, on a wave-swept rock which only shows itself at short intervals during the day, the preparation of the foundations is not an exacting task. A little paring with chisels and dynamite may be requisite here and there, but invariably the engineer takes the exposed surface as the basis for his work. The sea has eaten away all the soft, friable material in its ceaseless erosion, leaving an excellent foundation to which the superstructure can be keyed to become as solid as the rock itself.
When the beacon is to be erected upon a sandy bottom, the engineer’s work becomes more baffling, as he is compelled to carry his underwater work down to a point where a stable foundation may be secured. When the Leasowe lighthouse was built on the sandy Wirral shore, the builders were puzzled by the lack of a suitable foundation for the masonry tower. An ingenious way out of the difficulty was effected. In the vicinity an incoming ship, laden with a cargo of cotton, had gone ashore and had become a total wreck. The cotton was useless for its intended purpose, so the bales were salvaged and dumped into the sand at the point where the lighthouse was to be erected. The fleecy mass settled into the sand, and under compression became as solid as a rock, while its permanency was assured by its complete submersion. The stability of this strange foundation may be gathered from the fact that the tower erected thereon stood, and shed its welcome light regularly every night, for about a century and a half, only being extinguished two or three years ago as it was no longer required.
In the Old World, and, indeed, in the great majority of instances, the lighthouse is what is described as a “monolithic structure,” being built of courses of masonry, the blocks of which are dovetailed together not only laterally, but also perpendicularly, so that, when completed, the tower comprises a solid mass with each stone jointed to its fellow on four or five of its six sides. This method was first tried in connection with the Hanois lighthouse, off the Guernsey coast, and was found so successful that it has been adopted universally in all lighthouses which are exposed to the action of the waves.
The upper face and one end of each block are provided with projections, while the lower face and the other end are given indentations. Thus, when the block is set in position, the projections fit into corresponding indentations in the adjacent blocks, while the indentations receive the projections from two other neighbouring pieces. The whole is locked together by the aid of hydraulic cement. Consequently the waves, or any other agency, cannot possibly dislodge a stone without breaking the dovetails or smashing the stone itself. For the bottom layer, of course, the surface of the rock is pared away sufficiently to receive the stone, which is bedded in cement adhering to both the rock and the superimposed block. A hole is then drilled through the latter deep into the rock beneath, into which a steel rod or bolt is driven well home, and the hole is sealed up with cement forced in under such pressure as to penetrate every interstice and crevice.
The iron supports constitute the roots, as it were, of the tower, penetrating deep into the heart of the rock to secure a firm grip, while the tower itself resembles, in its general appearance, a symmetrical tree trunk, this form offering the minimum of resistance to the waves. The lower part of the tower is made completely solid by the dovetailing of the integral blocks, and is cylindrical in shape up to a certain predetermined level which varies according to the surrounding conditions and the situation of the light. Some years ago the lighthouse assumed its trunk-like shape at the bottom course, rising in a graceful concave curve to the lantern; but this method has been abandoned, inasmuch as, owing to the decreasing diameter of the tower as it rose course by course above its foundations, the lowest outer rings of masonry did not have to withstand any of the superimposed weight, which naturally bears in a vertical line. By carrying the lower part to a certain height in the form of a cylinder, and then commencing the concave curve of the tower, the pressure of the latter is imposed equally upon the whole of its foundations. The latter may be stepped—i.e., one tier of stones may project a little beyond that of the one immediately above—but this arrangement is adopted in order to break the smashing force of the waves.
The conditions attending the actual building operations upon the rock, which may be accessible only for an hour or two per day in calm weather, prevent the blocks of granite being shaped and trimmed upon the site. Accordingly, the lighthouse in the first place is erected piecemeal on shore. A horizontal course of stones is laid to see that each dovetail fits tightly and dead true. The next course is laid upon this, and so on for perhaps eight or ten courses, the trimming and finicking being accomplished as the work proceeds. Each projection has to be only just big enough to enter its relative indentation, while the latter must be exactly of the requisite dimensions to receive the projection, and no more. Each stone is then given an identification mark, so that the masons on the rock may perceive at a glance its precise position in a course, and to what ring of stones it belongs. Therefore the mason at the site has no anxiety about a stone fitting accurately; he has merely to set it in position upon its bed of cement.
On shore—generally in the quarry yard—when a series of courses have been temporarily built up in this manner and have received the critical approbation of the resident engineer, the topmost course is removed and retained, while the other blocks are despatched to the site. This topmost course forms the bottom ring in the next section of the lighthouse which is built up in the yard, and the topmost course of this section in turn is held to form the bottom course of the succeeding part of the tower, and so on from foundation to lantern parapet.
During the past two or three years reinforced concrete has been employed to a certain extent for lighthouse construction, but granite of the finest and hardest quality still remains the material par excellence for towers erected in exposed, sea-swept positions. The Russian lighthouse authorities have adopted the ferro-concrete system in regard to one or two shore lights, especially on the Black Sea, while another fine structure upon this principle was built by the French Service des Phares in 1905 at the entrance to the River Gironde. The system has also been adopted by the Canadian lighthouse authorities; one or two recent notable lights under their jurisdiction have been constructed in this material, although on somewhat different lines from those almost invariably followed, so far as the general design is concerned.
While the masonry or monolithic structure is the most durable and substantial structure, it is also the most expensive. In many parts of the world, notably along the Atlantic coastline of the United States, what are known as “screw-pile lighthouses” are used. These buildings vary in form, some resembling a huge beacon, such as indicates the entrance to a river, while others convey the impression of being bungalows or pavilions on stilts. The legs are stout, cylindrical, iron members, the lower ends of which are shaped somewhat after the manner of an auger, whereby they may be screwed into the sea-bed—hence the name. This system has been employed for beacons over dangerous shoals; and while they are somewhat squat, low-lying lights, they have proved to be highly serviceable.
Iron has been employed also for lighthouse constructional work, the system in this case being a combination of the screw pile and the tower, the latter, extending from a platform whereon the living-quarters are placed and mounted clear of the water, on piles, being a huge cylindrical pipe crowned by the lantern. One of the most interesting and novel of these iron lighthouses is the Hunting Island tower off the coast of South Carolina. In general design it resembles the ordinary lighthouse wrought in masonry, and it is 121½ feet in height from the ground to the focal plane. It is built of iron throughout, the shell being in the form of panels, each of which weighs 1,200 pounds.
This type of tower was selected owing to the severe erosion of the sea at the point where it is placed. When it was erected in 1875, at a cost of £20,400, or $102,000, it was planted a quarter of a mile back from the sea. This action was severely criticized at the time, it being maintained that the light was set too far from the water’s edge to be of practical value; but the hungry ocean disappointed the critics, because in the course of a few years the intervening strip of shore disappeared, and the necessity of demolishing the light and re-erecting it farther inland arose. On this occasion the engineers determined to postpone a second removal for some time. The tower was re-erected at a point one and a quarter miles inland, and the sum of £10,200, or $51,000, was expended upon the undertaking. The iron system, which was adopted, proved its value in this work of removal piece by piece, because, had the tower been carried out in masonry, it would have been cheaper to set up a new light, as was done at Cape Henry.
Fig. 1.—Sectional Diagram of the Ar-men Lighthouse, showing Yearly Progress in Construction.
It guards the “Bay of the Dead,” off Cape Finisterre. Commenced in 1867, it was not finished until 1881.
Some of the American coast lights are of the most primitive and odd-looking character, comprising merely a lofty skeleton of ironwork. The lamp is a head-light, such as is carried by railway engines, fitted 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.