Transcriber’s Note
Cover created by Transcriber, using an illustration from the original book, and placed in the Public Domain.

LIGHTSHIPS AND LIGHTHOUSES

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.

ILLUSTRATED

PHILADELPHIA: J. B. LIPPINCOTT COMPANY
LONDON: WILLIAM HEINEMANN
1913

Printed in England.

PREFACE

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.

CONTENTS

LIST OF ILLUSTRATIONS

CHAPTER I
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.

CHAPTER II
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.

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.

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.

Nowadays, owing to the skill in designing and the workmanship displayed, one never hears of a modern lighthouse collapsing. Expense is no object; the engineer does not endeavour to thwart the elements, but follows a design wherein the minimum of resistance is offered to them.

CHAPTER III
THE LIGHT AND ILLUMINANTS

While it is the tower that probably creates the deepest impression upon the popular mind, owing to the round of difficulties overcome associated with its erection, yet, after all, it is the light which is the vital thing to the navigator. To him symmetry of outline in the tower, the searching problems that had to be solved before it was planted in a forbidding spot, the risks that were incurred in its erection—these are minor details. His one concern is the light thrown from the topmost height, warning him to keep off a dangerous spot and by its characteristic enabling him to determine his position.

I have described the earliest type of light, the open wood or coal fire blazing on an eminence. In due course the brazier gave way to tallow candles. This was an advance, certainly, but the range of the naked light was extremely limited. Consequently efforts were made to intensify it and to throw it in the desired direction. The first step was made with a reflector placed behind the illuminant, similar to that used with the cheap wall-lamp so common in village workshops. This, in its improved form, is known as the “catoptric system,” the reflector being of parabolic shape, with the light so disposed that all its rays (both horizontal and vertical) are reflected in one direction by the aid of a highly polished surface. While the catoptric system is still used on some light-vessels, its application to important lighthouses has fallen into desuetude, as it has been superseded by vastly improved methods. But the reflector, made either of silvered glass set in a plaster-of-Paris mould or of brightly polished metallic surfaces, held the field until the great invention of Augustin Fresnel, which completely revolutionized the science of lighthouse optics.

Fig. 2.—Fixed Apparatus of 360 Degrees.

Shows one ray throughout the complete circle.
(By permission of Messrs. Chance Bros. and Co., Ltd.)

Fresnel was appointed a member of the French Lighthouse Commission in 1811, and he realized the shortcomings of the existing catoptric method only too well. Everyone knows that when a lamp is lighted the luminous rays are diffused on every side, horizontally as well as vertically. In lighthouse operations the beam has to be thrown in a horizontal line only, while the light which is shed towards the top and bottom must be diverted, so that the proportion of waste luminosity may be reduced to the minimum. While the parabolic reflector achieved this end partially, it was far from being satisfactory, and Fresnel set to work to condense the whole of the rays into a horizontal beam. Buffon, a contemporary investigator, as well as Sir David Brewster, had suggested that the end might be met by building up a lens in separate concentric rings, but neither reduced his theories to practice.

Fresnel invented a very simple system. He took a central piece of glass, which may be described as a bull’s-eye, and around this disposed a number of concentric rings of glass. But these rings projected beyond one another. Each constituted the edge of a lens which, while its radius differed from that of its neighbour, owing to its position, yet was of the same focus in regard to the source of illumination. The parts were shaped with extreme care and were united in position by the aid of fish glue, the whole being mounted in a metal frame. The advantage of the system was apparent in the first demonstrations. The lenses being comparatively thin, only one-tenth of the light passing through was absorbed, whereas in the old parabolic reflectors one-half of the light was lost.

Fig. 3.—Single Flashing Apparatus (One Panel and Mirror).

(By permission of Messrs. Chance Bros. and Co., Ltd.)

This revolutionary development was perfected in 1822, and in the following year it was submitted to its first practical application on the tower of Cordouan in the Gironde. Several modifications were made by the inventor for the purpose of adapting his system to varying conditions. One of the most important was the disposition of lenses and mirrors above the optical apparatus for the purpose of collecting and driving back the rays which were sent out vertically from the illuminant, so that they might be mingled with the horizontal beam, thereby reinforcing it. At a later date similar equiangular prisms were placed below the horizontal beam so as to catch the light thrown downwards from the luminous source, the result being that finally none, or very little, of the light emitted by the illuminant was lost, except by absorption in the process of bending the rays into the desired direction.

Fig. 4.—A Twenty-Four Panel Light, which was introduced into Certain French Lighthouses.

In this ingenious manner the circle of light is divided into sections, called “panels,” each of which comprises its bull’s-eye and its group of concentric rings and prisms. The extent of this division varies appreciably, as many as sixteen panels being utilized in some instances. In this direction, however, subdivision can be carried too far. Thus, in some of the French lighthouses no less than twenty-four panels were introduced. The disadvantage is obvious. The total volume of light emitted from the luminous source has to be divided into twenty-four parts, one for each panel. But the fewer the panels, the more light is thrown through each, and the correspondingly greater power of the beam. Thus, in a four-panel light each beam will be six times as powerful as that thrown from a twenty-four panel apparatus of the same type.

Fresnel also introduced the system of revolving the optical apparatus, and by the introduction of suitable devices was able to give the light a flashing characteristic, so that it became possible to provide a means of identifying a light from a distance entirely by the peculiarity of its flash. The French authorities were so impressed with the wonderful improvement produced by Fresnel’s epoch-making invention that it was adopted immediately for all French lights. Great Britain followed suit a few years later, while other countries embraced the system subsequently, so that the Fresnel lens eventually came into universal use.

Fig. 5.—A Four-Panel Light.

The ray thrown through each panel is six times as powerful as the beam thrown through a twenty-four panel apparatus.

But the Frenchman’s ingenious invention has been developed out of recognition. To-day only the fundamental basis is retained. Marked improvements were made by Mr. Alan Stevenson, the famous Scottish lighthouse engineer. In fact, he carried the idea to a far greater degree than Fresnel ever contemplated, and in some instances even anticipated the latter’s subsequent modifications and improvements. This was demonstrated more particularly in the holophotal revolving apparatus, the first example of which he designed for the North Ronaldshay lighthouse in 1850, a similar apparatus being devised some years later by Fresnel. In 1862 another great improvement was made by Mr. J. T. Chance, of the well-known lighthouse engineering firm of Birmingham, which proved so successful that it was incorporated for first and third order apparatuses in the New Zealand lights designed by Messrs. Stevenson in the same year.

Fig. 6.—Single Apparatus in Four Panels.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

The French and British investigators, however, were not having things entirely their own way. The United States played a part in these developments, although they did not enter very successfully into the problem. The first lighthouse at Boston Harbour carried candles until superseded by an ordinary lamp, which was hung in the lantern in much the same way as it might have been suspended behind the window of a private dwelling. An inventor, Mr. Winslow Lewis, who confessed that he knew nothing about lighthouse optics, patented what he called a “magnifying and reflecting lantern” for lighthouse work, which he claimed was a lamp, a reflector, and a magnifier, all in one. It was as crude a device as has ever emanated from an inventive brain, but the designer succeeded in impressing the Government so effectively that they gave him £4,000, or $20,000, for his invention. The reflector was wrought of thin copper with a silvered surface, while the magnifier, the essence of the invention, was what he called a “lens,” but which in reality comprised only a circular transparent mass, 9 inches in diameter, and varying from 2½ to 4 inches in thickness, made of bottle-green glass. The Government considered that it had acquired a valuable invention, and was somewhat dismayed by the blunt opinion of one of its inspectors who held contrary views concerning the magnifier, inasmuch as he reported cynically that its only merit was that it made “a bad light worse.”

Fig. 7.—Double Flashing Apparatus: Two Panels and Mirror.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

Fig. 8.—Double Flashing Apparatus: Two Groups each of Two Panels.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

The inventor did not manifest any antagonism to this criticism, but immediately pointed out the great economy in the consumption of oil that was arising from the use of his idea. Indeed, he prosecuted his claims so successfully that he clinched a profitable bargain to himself with the Government. His apparatus had been fitted to thirty-four lights, and he contracted to maintain them on the basis of receiving one-half of the oil previously consumed by the lamps which his invention superseded. This arrangement was in vogue for five years, when it was renewed, with the difference that on this occasion the Government, concluding that the inventor was making too much out of the transaction, reduced the allowance to one-third. Subsequently the invention received higher commendation from the officials than that advanced by the critical inspector, although it must be pointed out that meanwhile the magnifying bull’s-eye had been abandoned, and a new type of reflector introduced, so that the sole remaining feature of the wonderful invention was the lamp. Even that had been modified. When the Lighthouse Board was established in 1852 it abolished the much-discussed invention, and introduced the Fresnel system, bringing the United States into line with the rest of the world.

Fig. 9.—Triple Flashing Apparatus: Three Panels and Mirror.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

One feature of the subject cannot fail to arrest attention. This is the possibility of producing a variety of combinations by the aid of the lenses to fulfil different requirements. The Fresnel, Stevenson, and Chance developments in the science of lighthouse optics facilitated this work very significantly. Accordingly, to-day a variety of lights, evolved from the variations in the mounting of the lenses, is in vogue. For purposes of identification they have been divided into a number of classifications, and, for the convenience of the navigator, are described as lights of the first order, second order, and so on. Broadly speaking, there are seven main groups, or orders, the rating only applying to dioptric or catadioptric lights, indicating the bending of the luminous rays in the desired direction, either by refraction and reflection through the medium of prisms, or a combination of both. Actually there is a distinction between these two, the true dioptric system referring only to refraction, where the ray is bent in the desired direction by a glass agent, known as a “refracting prism.” In the catadioptric system, on the other hand, both methods are employed, since the prism performs the dual purpose of reflecting and refracting the rays. However, in modern lighthouse parlance both are grouped under the one distinction “dioptric.”

The rating or classification of the lights varies according to the inside radius or focal distance of the lens—in other words, the distance from the centre of the light to the inner surface of the lens. The main groups are as follows:

The most powerful apparatus used to-day, however, is that known as the “hyperradiant,” and it is the largest which has yet been devised. For this, lighthouse engineering is indebted to Messrs. Stevenson, the engineers to the Commissioners of Northern Lighthouses. It was first suggested as far back as 1869, and experiments were carried out which emphasized the fact that such an apparatus was required, since it was found that when large gas-burners were used much of the light in revolving apparatuses was out of focus and escaped condensation. The Scottish engineers thereupon suggested that an apparatus should be used having a focal distance of 1,330 millimetres, or 52·3 inches. In fact, they went farther and suggested even larger apparatuses, but this idea has not matured. But it was not until 1885 that Messrs. Stevenson had such a system manufactured, and then it was tested at the South Foreland beside the powerful lenses which had just been built for the new Eddystone and the Mew Island lighthouses. The merits of the theories advanced by Messrs. Stevenson were then completely proved, for it was found that with a ten-ring gas-burner the hyperradiant apparatus threw a light nearly twice as powerful as that given by the rival lenses with the same burner.

Fig. 10.—Quadruple Flashing Apparatus: Four Panels.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

At the present moment the hyperradiant is regarded as the ultima thule of lighthouse optical engineering, and Messrs. Chance Brothers and Co., of Birmingham, have built some very magnificent apparatuses of this order. At present there are not more than a dozen such powerful lights in operation. Three are on the English coast, at Bishop Rock, Spurn Point, and Round Island, respectively; two in Scotland, at Fair Isle and Sule Skerry; two in Ireland, at Bull Rock and Tory Island; one in France, at Cap d’Antifer; one in China, at Pei Yu-shan; one in India, at Manora Point, Karachi; and the Cape Race light in Newfoundland. The hyperradiant apparatus is a massive cage of glass, standing some 12 feet in height, and, as may be supposed, is extremely expensive.

There is another point in lighthouse optics which demands explanation. This is the term “divergence,” which plays an important part in the duration of the flash. In speaking about focus, the engineer follows somewhat in Euclid’s footsteps in regard to the definition of a point; in a way it is equally imaginary. The focal point does not mean the whole of the flame, but the centre of the luminous source, and, as is obvious, it is impossible to secure a flame without dimensions. It may be an attenuated, round, oval, or fan-shaped light—the result is the same. The focal point is the theoretical centre of the luminous source, and the rays, coming from the top, sides, and bottom of the flame cannot come from the true focus. If they did, all the light from one panel would be emitted in absolutely parallel lines, and therefore in a revolving apparatus the beam would pass any given point on the horizon in an infinitely short period of time—to be precise, instantaneously. But the ex-focal rays of the flame, in passing through the lens, emerge at an angle to those coming from the absolute centre, so that the whole beam becomes “diverged,” and throws a cone of light from the lens. Consequently the beam occupies an appreciable period of time in passing a given point on the horizon.

As may be supposed, the intricate character of the lenses constituting the optical apparatus of the modern lighthouse demands the highest skill and infinite care in their preparation, while the composition of the glass itself is a closely guarded secret. There are less than half a dozen firms in the world engaged in this delicate and highly specialized work, of which France claims three, Germany one, and Great Britain one. All the lighthouse authorities of the various nations have to secure their requirements from one or other of these organizations. The industry commenced in France, and for many years the French reigned supreme. Then it contrived to make its entrance into England, and was taken up by the family of Chance in Birmingham, who soon proved themselves equal to their French leaders.

Fig. 11.—Red and White Flashing Apparatus.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

The British firm has established a unique reputation, as it has been responsible for the majority of the great lights of the world, some of which are not only of huge dimensions and weight, but also of novel form. The hyperradial apparatuses which have been placed recently in the towers of Manora Point and Cape Race probably rank as the most powerful and the finest in existence. These are used in conjunction with the petroleum vapour incandescent burner. The Cape Race light, for instance, comprises a revolving optic of four panels, subtending a horizontal angle of 90 degrees, with a vertical angle of 121½ degrees. Each lens comprises the central disc, or bull’s-eye, around which are placed nine rings of glass, giving a total refracting angle of 57 degrees. In order to bend the vertical rays into a horizontal path twenty-two catadioptric reflecting prisms are disposed above the lens, while below are thirteen similar prisms. The total amount of glass worked into the four panels is about 6,720 pounds, and the prisms are mounted in gun-metal frames, which weigh approximately 4,800 pounds, so that the total weight of the glass portion and its mounting alone, standing some 12 feet in height, is over 11,500 pounds. The installation completed for the equipment of the Manora Point lighthouse, Karachi, is very similar.

In some cases the demand for a powerful light has been met with a system differing from the “hyperradiant.” The lenses and respective groups of refractors are superimposed, each tier having its individual burner and flues for carrying off the products of combustion. In this way we have the biform, comprising two such panels arranged one above the other, as in the Fastnet and Eddystone lights; and the quadriform, wherein four tiers are built one above the other, as installed at the Mew Island light in Ireland. The advantage of this arrangement is that a beam of great intensity is secured with a lantern of comparatively small diameter.

The French authorities adopted a modification of this system. Instead of placing two lenses and refractors one above the other, they ranged them side by side, the effect being analogous to a couple of squinting eyes, the panels being parallel and therefore throwing out parallel beams. But these adaptations have not come into extensive use, as they have been superseded by more simple means of achieving similar requirements with an even more powerful ray. The hyperradiant stands as the finest type of apparatus yet devised, and therefore is employed when an extremely powerful light is required.

While the design and arrangement of the optical apparatus is certainly a most vital and delicate task, the mounting thereof upon a substantial support in such a way that it may perform its work with the highest efficiency is equally imperative, since the finest apparatus might be very adversely affected by being improperly mounted.

Fig. 12.—Apparatus showing a Double Flash, followed by a Single Flash.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

Obviously, owing to the great weight of the glass, the support must be heavy and substantial. A massive cast-iron pedestal is employed for this purpose. When the light is of the revolving character, means have to be incorporated to secure the requisite rotation. In the early days the turntable upon which the lens is mounted ran upon rollers, but now a very much better system is universally employed. This has been brought to a high standard of perfection by Messrs. Chance of Birmingham, who have carried out unceasing experiments in this field. The objection to rollers was the enormous friction that was set up, and the great effort that was required, not only to set the lenses revolving, but to keep them rotating at a steady pace. In the modern apparatus the rollers are superseded by an iron trough filled with mercury, upon which floats the turntable carrying the lenses. When the apparatus is properly built and balanced, the friction is so slight that the turntable can be set in motion by the little finger, notwithstanding that several tons have to be moved. Although the optical part of the apparatus floats upon the bed of quicksilver in the same way as a cork lifebelt floats upon water, it is provided with rollers which serve to hold the whole apparatus steady and to overcome any oscillation.

In the case of an immense apparatus such as a hyperradiant lens, which, together with the turntable, may have a total weight of 17,000 pounds, an enormous quantity of mercury is required. The trough of the Cape Race hyperradiant light carries 950 pounds of quicksilver, upon which the lantern is floated. In such an instance, also, the pedestal is a weighty part of the apparatus, representing in this case about 26,800 pounds, so that the complete apparatus utilized to throw the 1,100,000 candle-power beam from the guardian of the Newfoundland coast aggregates, when in working order, some 44,000 pounds, or approximately 20 tons.

Within the base of the pedestal is mounted the mechanism for rotating the optical apparatus. This is of the clockwork type driven by a weight. The latter moves up and down a tube which extends vertically to a certain depth through the centre of the tower. The weight of the driving force and the depth of its fall naturally vary according to the character of the light. In the Cape Race light the weight is of 900 pounds, and it falls 14½ feet per hour. Similarly, the length of time which the clock will run on one winding fluctuates. As a rule it requires to be rewound once every sixty or ninety minutes. A longer run is not recommended, as it would demand a longer weight-tube, while many authorities prefer the frequent winding, as the man on duty is kept on the alert thereby. As the weight approaches the bottom of its tube it sets an electric bell or gong in action, which serves to warn the light-keeper that the mechanism demands rewinding.

Fig. 13.—The Classification of Lights, showing the Respective Radius or Focal Distance of Lens from 150 to 1,330 Millimetres.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

The weight and clockwork mechanism perfected by Messrs. Chance is regarded as one of the best in service. The rotation is perfect and even, owing to the governing system incorporated, while the steel wire carrying the weight is preferable to the chain, which is subject to wear and is noisy in action. In the Chance clockwork gear the weight is just sufficient to start the apparatus from a state of rest, the advantage of such a method being that, should the apparatus be stopped in its revolution from any untoward incident, it is able to restart itself.

Of course, the clockwork mechanism is required only in those cases where the lenticular apparatus has to be revolved. This introduces the question of avoiding confusion between lights. When beacons were first brought into service, the lights were of the fixed type, and the navigator, although warned by the glare to keep away from the spot so marked, was given no information as to his position. Accordingly, lighthouse engineers sought to assist him in this direction during the blackness of the night by providing a ready visual means of identification. Owing to the ingenuity which has been displayed, it has been rendered possible to ring the changes upon a light very extensively.

These may be subdivided broadly as follows:

In the foregoing classifications only a white light is used. But it may so happen that the lighthouse, owing to its position and the dangerous character of the spot which it marks, carries a light which changes colour from white to red or green, which are shown alternately in various combinations. These characteristics are indicated as follows:

In timing a revolving or flashing light, the cycle is taken from the beginning of one flash to the beginning of the next. In these readings the flash is always shorter than the duration of the eclipse, while an occultation is shorter than, or equal to, the length of the light interval. Since flashing and occulting may be carried out with a fixed light suddenly extinguished or eclipsed, the characterization is determined solely according to the relative duration of light and darkness, irrespective of the type of apparatus employed or the relative brilliancy. There is one peculiarity of the flashing light which may be remarked. At short distances and in clear weather a faint continuous light may be shown.

Hand in hand with the development of the optical apparatus has been the wonderful improvement in regard to the illuminants and the methods of producing a brilliant clear flame. The fuel first used upon the introduction of the oil lamp was sperm or colza oil, the former being obtained from the whale, and the latter from seeds and a wild-cabbage. Both were very expensive, so that the maintenance of a light was costly—so much so that the United States authorities devoted their efforts to the perfection of a high-class lard-oil. This proved highly satisfactory, possessing only one drawback. In winter it congealed so much under the low temperature that it had to be heated before it could be placed in the lamp; but once the light was set going, the heat radiated from the burner served to keep the oil sufficiently fluid to enable it to mount the wick to the point of combustion under capillary action.

So far as the American authorities were concerned, the advantages of lard-oil sufficed to bring a cheaper medium than colza-oil into vogue. A company, which had been induced by the Government to install an elaborate and expensive plant for the production of colza-oil, after prolonged experiment and efforts to reduce the cost of production, announced that it could not compete with the lard-oil, and suggested that the latter should be employed in preference to the colza. The Government agreed, but, to compensate the company for its trouble, purchased the plant which the latter had laid down.

The advances in the processes for refining petroleum, and the exploitation of the extensive resources of the latter, led to “earth-oil,” in some form or other, being employed for lighthouse purposes. The attempt was facilitated by the invention and improvement of the Argand burner, whereby a brilliant white annular sheet of flame is produced. Various lighthouse engineers devoted their attention to the improvement of this burner in conjunction with paraffin. Their results were completely successful, and at last paraffin became universally utilized as the cheapest and most efficient illuminant known.

The general method of feeding the lamps was to pump the oil from a low level to the burner, thereby producing practically a pressure-feed system in preference to the capillary action which is used in the ordinary household lamp. By increasing the number of rings the intensity of the flame was increased, until at last it was thought that with this development perfection had been attained so far as lamps were concerned.

Then came another radical revolution. The invention of the incandescent gas mantle by Dr. von Auer, and the complete change that it wrought in connection with gas lighting, induced lighthouse engineers to experiment in this field. As they could not use coal-gas, they devoted their investigations to the perfection of a gas from petroleum, which should be capable of combustion with the incandescent burner. Many years were devoted to these experiments, and many petroleum vapour systems were devised. One of the best known, most successful, and most scientifically perfect, is the Chance incandescent light. This burner is used in many of the most powerful lights of the world and has given complete satisfaction. The mantle varies in size with the size and type of the light, ranging from 35 to 85 millimetres in diameter, the latter, in conjunction with a hyperradial apparatus, producing a light exceeding 1,000,000 candle-power.

By courtesy of Messrs. Chance Bros. & Co., Ltd.

THE HYPERRADIAL APPARATUS FOR THE MANORA POINT LIGHT, KARACHI, INDIA.

Of 1,330 millimetres focus, this is the most powerful and largest lighthouse apparatus made.

Not only was a far more powerful light obtained in this manner with the assistance of the petroleum vapour burner and incandescent mantle, but the cost of maintaining the light was reduced, owing to the great economy in oil consumption that was effected thereby, the largest mantle and burner—85 millimetres—burning only 2½ pints of oil per hour. The light thus obtained, while being vastly superior to that derived from a six-wick oil-burner, enables a saving of nearly £48, or $240, per annum to be recorded, taking the cost of the petroleum at 1s., or 25 cents, per gallon delivered to the lighthouse.

While petroleum is generally used, some countries have adopted other oil fuels for small permanent lights. Thus, in Germany compressed oil-gas, water-gas associated with benzine vapour, and Blau liquid gas, are utilized. The last-named is coming very extensively into vogue, also, in Holland, Denmark, and Austria. Blau gas has the advantage that it can be transported in small steel tanks under extremely high pressure—up to 100 atmospheres, or approximately 1,400 pounds per square inch. It is an extract of oil-gas produced at a low pressure in the gas retorts, and then compressed so severely that it liquefies. The fuel, as it is drawn from the cylinder in which it is stored, has the pressure reduced by means of a valve, so that it reaches the burner in a gaseous form at a pressure equivalent to that of the coal-gas used in private houses, and is burned in the same way with an incandescent mantle. The advantage of this method lies in the facility with which large volumes of gas may be transported, a steel cylinder containing 7,500 cubic feet weighing only 132 pounds. It is also inexpensive, a bottle of the foregoing capacity costing only 12s. 6d., or $3. In some cases the incandescent mantles, the average life of which is about a fortnight, are of large diameter, running up to 100 millimetres, or about 4 inches.

Recently Mr. Gustaf Dalén, of the Gas Accumulator Company of Stockholm, the inventor of the Dalén flasher and sun-valve, which are described elsewhere, has introduced a new illuminant, which is coming into vogue, especially on the Continent. This is called “Daléngas,” and is a mixture of 9 per cent. dissolved acetylene and 91 per cent. atmospheric air. Here the dissolved acetylene gas is conducted from a storage reservoir or high-pressure gas cylinder, of special construction, to a governor, where the pressure is reduced, and then to the mixing apparatus, where the acetylene gas is associated with the air in the above proportions. The idea of this combination and method is to enable an acetylene gas mixture to be used with the ordinary incandescent mantles.

By courtesy of Messrs. Chance Bros. & Co., Ltd.

FIRST ORDER TRIPLE FLASHING LIGHT OF 920 MILLIMETRES FOCAL DISTANCE FOR CHILANG LIGHTHOUSE, CHINA.

The advantage of the Daléngas, according to present experience, is the increased candle-power that is obtainable as compared with other systems, the superiority being about 75 per cent. under ordinary conditions. With the largest Fresnel lenses a lighting power of 200,000 Hefner candle-power is secured, while with revolving lenses of the latest type a beam of 3,000,000 candle-power can be obtained. The flame is small, and thus becomes concentrated more in the focus of the lens, so that the divergence of the light may be diminished if desired. When a light of a certain range is to be installed, the optical apparatus can be made smaller for Daléngas than for other illuminants, and the cost is reduced correspondingly. Similarly, if the system is introduced into an existing light, the latter can be made appreciably more powerful, without changing the optical apparatus or affecting the divergence.

In this system the gas is conducted into the lens apparatus from above, and the lighting arrangement is quite independent of, and does not interfere in any way with, the revolving apparatus, while the time spent in changing the mantle is less than half a minute.

All combustible gases, mixed with air in certain proportions, may produce more or less violent detonations when fired. But the quantity of mixed gas in this instance is confined in the length of piping between the burner and the mixing apparatus, and this quantity is so small that an explosion cannot be dangerous. In fact, all such danger has been guarded against completely—is, indeed, impossible in any circumstances.

Electric light has been adopted in one or two cases; but while the foremost authorities agree that it throws the best, most brilliant and most powerful beam of light, the system is generally impracticable on account of its great cost. When tests with this light were made some years ago in comparison with the light thrown from oil burners, it was claimed that the latter, owing to its reddish-yellow tinge, was the most suitable from the all-round point of view, and that it could penetrate to a greater distance in foggy weather. I have been informed by several authorities, who have gone more deeply into this question since, that this is a fallacy, and that the advantage rests completely with electric light. Experience in Germany, which has two magnificent electric lighthouses, and in Scotland, certainly supports this contention, and I have been assured that the sole reason why electric lighting has not been adopted more widely is the heavy cost, both of installation and of maintenance. When electric lighting is rendered cheaper and is brought more to the level of existing lighting arrangements, one may expect another complete change in lighthouse practice. In this direction, as explained in another chapter, the Germans have carried out practical experiments in their characteristic manner, and have brought the cost of maintaining a most powerful electric light to the minimum.

One very great advantage of the electric light is the ease with which the power of the beam may be increased during thick weather, so as to secure penetration to the greatest distance, and decreased to suit easier conditions in clear weather.

This point raises the question, “From how far can a light be seen out at sea?” This factor is influenced by climatic conditions, and also by the curvature of the earth. The higher the light, or the spectator, or both, is elevated above the water, the greater the distance from which the light can be seen. The table on p. [52], prepared by Mr. Alan Stevenson, the eminent Scottish lighthouse engineer, gives the distances at which objects can be seen at sea, according to the respective elevations of the object and the eye of the observer.

For instance, the passenger on a liner the boat-deck of which is 40 feet above the water, approaching the English Channel, will sight the Bishop Rock light from a distance of about 22 miles, because the focal plane—that is, the bull’s-eye of the lens—is 163 feet above the water, which, according to the following table, equals about 14½ miles, to which must be added the height of the boat’s deck, 40 feet representing 7·25 miles. Similarly, the ray of the Belle Ile light will come into view when the vessel is 32½ miles distant—height of focal plane of light, 470 feet = 25 miles, + eye of observer on board the liner, 45 feet = 7·69 miles; while the Navesink light, being 246 feet above the water, may be picked up by the captain of a liner from a distance of 28 miles. The range of many lights, however, owing to the curvature of the earth, is greatly in excess of their geographical range, and with the most powerful lights the glare of the luminous beams sweeping the clouds overhead may be seen for a full hour or more before the ray itself comes into view.

TABLE OF DISTANCES AT WHICH OBJECTS CAN BE SEEN AT SEA, ACCORDING TO THEIR RESPECTIVE ELEVATIONS AND THE ELEVATION OF THE EYE OF THE OBSERVER.

By permission of the “Syren and Shipping.”

LOOKING UP THE LANTERN OF THE NEEDLES LIGHTHOUSE.

So far as the candle-power of any light is concerned, the method of determining this factor, varying according to the calculating methods adopted, is somewhat misleading. So far as Great Britain is concerned, the practice of setting out the candle-power of any light in the official list has been abandoned, the authorities merely stating that such and such a light is of great power. The United States and Canada, on the other hand, indicate the approximate candle-power.

By courtesy of Messrs. Chance Bros. & Co., Ltd.

FIXED APPARATUS OF THE FOURTH ORDER FOR SARAWAK.

The focal distance is 250 millimetres, and the diameter of lantern inside glazing 6 feet 7¾ inches.

By combining and arranging the integral parts of the optical apparatus, the lighthouse engineer is able to accomplish many astonishing results. Thus, while the various types generally follow accepted broad lines, coinciding with the order which they represent, here and there some very striking divergences are made. The Bell Rock light is perhaps the most interesting example in this direction. It was designed by Messrs. D. and T. Stevenson, and built by Messrs. Chance Brothers and Co. The light is alternating, the colours being white and red. Externally the optical apparatus appears to be bizarre, yet it is one of the most perfect which has ever been installed. In its design and construction almost all the known lighthouse optical elements are incorporated, including the equiangular refractor, the reflecting prism, the double-reflecting prism, and the dioptric mirror. Another noteworthy fact is that, by an exceedingly ingenious arrangement, the absorption of the rays by the glass used in producing the red flashes is neutralized to such a vast degree that the white and red flashes are of equal intensity.

The subsidiary light is another striking feature which the lighthouse engineer has introduced. For instance, a light may be shown from a dangerous reef, and give the mariner all the warning desired. But some distance away may lurk another isolated rock, which it is just as imperative to indicate, and yet on which another tower cannot be erected. This necessity is met by the subsidiary light. A portion of the light from the main apparatus is deflected and thrown to the desired spot by an ingenious arrangement of the prisms. On the west coast of Scotland, at Stornoway, a stream of light used to be deflected from the lantern in a vertical direction down the tower, and there bent at right angles, to be thrown through a lower window and fall upon a prism placed on the crest of a rock several hundred feet distant. From the deck of a vessel, the effect of the light striking the prism was akin to that produced by a beacon. Similarly in the case of St. Catherine’s light in the Isle of Wight: a portion of the light, which would otherwise be wasted over the area on the landward side, is carried vertically down the tower by a disposal of lenses and prisms, and is projected horizontally through a small window, after being coloured into a red ray by passing through some glass of the desired tint, to mark a danger spot some distance away. This method, however, is not favoured now, as the peril can be more efficiently marked by means of an independent beacon, a system which has become feasible owing to the vast improvements that have been made in automatic lights requiring no attention for several weeks or months at a time.

But in those instances where the latter expedient is not adopted, the practice is to cover the danger with a ray thrown from an entirely different light. When the present Eddystone tower was completed, a “low-light room,” as it is called, was incorporated, and a low-powered light was thrown from two Argand burners and reflectors through a window to mark a dangerous reef some three miles distant. But perhaps the best example of a subsidiary light is that which was carried out by Messrs. Chance in connection with the Cap de Couedie lighthouse. In this instance two dangers had to be indicated in a subsidiary manner, one being covered with a red, the other with a green, ray. The red sector marks a danger spot known as Lipson’s Reef, lying 8¾ miles distant, while the green light indicates Casuarina Island, 1¾ miles away. This installation, it may be pointed out, has proved highly successful, and certainly is very economical.

Fig. 14.—The Means whereby the Rays are deflected from the Main Light to form a Subsidiary Light.

(By permission of Messrs. Chance Bros. and Co., Ltd.)

There is another point which deserves mention—the duration of the flash in a revolving light. There was considerable discussion and difference of opinion upon this question some years ago. It was maintained that the shorter the duration of the flash, and the more rapidly it were thrown, the better it would be for the mariner. The Scottish engineers realized the significance of this problem, and, despite the hostile criticism of contemporary engineers, adopted a specific principle which was to give a flash of two and three-quarter seconds’ duration. Subsequently it was reduced to one second. The introduction of the mercury float enabled the optical apparatus to be revolved faster, and also facilitated the reduction in the number of panels or faces, so that ultimately the Scottish engineers reduced the flash to one of four-tenths of a second.

When Mr. Bourdelles devised the mercury float which enabled rotation to be accelerated, the French authorities rushed to the opposite extreme. They reduced the faces to four, and arranged for the apparatus to be revolved at a high speed, so that the duration of the flash was only one-tenth of a second at rapidly-recurring intervals. This type of light was called the feu-éclair, and was adopted as a result of prolonged laboratory investigation. But this was an instance where laboratory experiments and scientific reasoning failed to go hand in glove with practical experience and navigation, where the mariner has to contend with all sorts and conditions of weather. The seafarer expressed his opinion of the one-tenth of a second flash in uncomplimentary terms, displaying an indifferent appreciation of artificially-produced sheet-lightning.

Eventually there was a general agreement, among all those countries which had investigated the problem closely, that a flash of about three-tenths of a second was the most satisfactory, and this has since become tacitly standardized. The French authorities recognized the fallacy of their idea, and soon came into line with the other countries.

CHAPTER IV
FOG-SIGNALS

Notwithstanding the wonderful ingenuity that is displayed in the concentration of light into powerful beams, these all count for nothing when fog settles upon the sea. The ray of 1,000,000 candle-power is almost as futile then as the glimmer from a tallow dip.

Fog is the peril of the sea which the mariner dreads more than any other. The blanket of mist, descending upon the water, not only shuts everything from sight, but deadens every sound as well. The sea is absolutely calm, so that no intimation of danger ahead is conveyed by the breaking of the waves upon rock, shoal, sandbank, or iron-bound coast.

It is in times of fog that the navigator must be given the greatest protection. As this is impossible to accomplish visually, appeal must be made to his ear. In the early days of lighthouse engineering the methods of conveying audible warning were very crude. The discharge of a gun was the most popular, but it was neither serviceable nor reliable, and was made upon somewhat haphazard lines. Thus, in the case of a dangerous headland on the North American coast, which the Boston steamer had to round on its journey, the keepers mounted guard at the probable time of the vessel’s arrival off this point. They listened eagerly for the steamer’s whistle, and when it came screaming over the water they began hurriedly firing a carronade, keeping up the blank-cartridge bombardment until another shriek told them that those on the vessel had heard their signals. Sometimes the whistle was heard from a distance of six miles; at others from not more than two miles away. It depended upon circumstances. Obviously, such a primitive system was attended with considerable danger, as an accident was liable to happen to the men in their feverish haste to load and discharge the gun, while the plight of the boat was far from being enviable at times.

By permission of Messrs. Chance Bros. & Co., Ltd.

A MODERN LIGHTHOUSE SIREN PLANT.

Showing gas engines and air-compressors in duplicate, with siren at side.

In the early days every lighthouse tower was provided with a heavy bell. Indeed, the ponderous dome of metal projecting from the lantern gallery was considered indispensable. The bell varied in weight from 1,200 to 2,240 pounds, was fitted with a massive clapper, and when struck emitted a deep musical note. In order to enable the seafarer to gain some idea of his whereabouts, the fog-signals were given a sound-characteristic somewhat upon the lines of those in connection with the light. Thus, one lighthouse would give one stroke every ten seconds; another would give two strokes in quick succession, followed by a long silence, and so on. This system suffers from the severe handicap that the sound does not travel very far during foggy weather.

Another ingenious engineer recommended the utilization of the locomotive whistle, giving a high-toned, ear-piercing shriek, but the same objection as attended the use of the bell prevailed: the sound could not be heard more than a short distance away. The British lighthouse authorities submitted the idea to a series of searching investigations to ascertain its possibilities, but eventually were compelled to conclude that it was not superior to, if as good as, the other systems then in vogue. The United States authorities, as a result of their independent experiments, expressed a similar opinion; but in Canada practical application gave this whistle a favourable verdict.

Rockets also have been adopted, and are highly successful. Indeed, this method of conveying audible warning prevails still in many countries. The practicability of such a means of throwing sound over a wide area was advanced by Sir Richard Collinson, when Deputy-Master of Trinity House, and his idea comprised the insertion of a gun-cotton charge, timed to explode at a given height, in the head of the rocket. The height could be varied up to about 1,000 feet, and the weight of the charge fluctuated according to requirements. The rocket system was tested very severely, and in some instances the report was heard as many as twenty-five miles away. It received the approbation of Professor Tyndall, and, although superior methods of signalling have been devised since, there remain one or two lighthouse stations where it is considered to be the most satisfactory fog-signalling device, notably the station on the island of Heligoland, where the rocket is hurled into the air to explode at a height of nearly 700 feet.

In many lighthouses the detonation of gun-cotton constitutes the means of conveying warning to passing vessels, but is accomplished in a different manner. The charge, instead of being sent into the air to be exploded, is attached to a special device which is supported upon a simple frame at a point above the lantern, so that no damage may be inflicted upon the glass of the latter from the concussion. The apparatus is fitted with a safety device which prevents premature explosion, so that the keeper is preserved from personal injury, and, unless culpable negligence is manifested, the charge cannot be ignited until it has been raised to its designed position. The report is of great volume, and as a rule can be heard a considerable distance; but in this, as in all other cases, the atmosphere plays many strange tricks. Still, it has not been superseded yet for isolated sea-rock lighthouses, such as the Eddystone, Skerryvore, and Bell Rock, where there is lack of adequate space for the installation of any other equally efficient fog-signalling facilities.

Photo, Paul, Penzance.

THE SIRENS OF THE LIZARD.

Owing to the importance of the Lizard Station and the fact that the coast often is obscured by fog, a powerful fog-signalling station is imperative.

In the early seventies an American investigator, Mr. C. L. Daboll, contrived an entirely new system, which developed into the foundation of one of the most successful fog-signalling devices for lighthouses which has been discovered—the siren. The Daboll invention was a huge trumpet, recalling a mammoth phonograph horn. It was 17 feet in length, and its mouth was 38 inches in diameter. In the lower end of this trumpet—the throat—was placed a tongue of steel measuring 10 inches in length and secured at one end to form a reed. It was blown by air compressed in a reservoir to the desired degree, and then permitted to escape through the trumpet. The mad rush of the expanding air through the constricted passage set the reed vibrating violently, causing the emission of a penetrating, discordant bellow. When Daboll commenced his experiments, he suffered from the lack of a suitable mechanical means for compressing the air, and made shift with a donkey for this purpose until the hot-air engine was improved, when the latter was substituted.

Trinity House adopted the idea and found it serviceable; but the Canadian authorities, after four years’ experiment, dissented from this view, remarking that the trumpet was expensive to maintain, unreliable in working, and liable to break down when most urgently needed. In fact, they characterized the Daboll trumpets which they had installed as “sources of danger instead of aids to navigation.”

From the trumpet to the siren was not a very big step. The history of the latter’s invention is somewhat obscure, but it was brought before the United States Government in a primitive form. The American engineers, recognizing its latent possibilities, took it up, and endeavoured to improve it to such a degree as to render it suitable for lighthouse work. Their efforts were only partially successful. The solution of the many difficulties attending its perfection was effected in Great Britain by Professor Frederick Hale Holmes, whose magneto-electric machine brought electricity within reach of the lighthouse as an illuminant, and it was due to the efforts of this scientist that the siren became one of the most efficient sound-producing instruments which have been discovered for this class of work.

The reason that made Professor Holmes bring his energies and knowledge to bear upon this subject was somewhat curious. The siren in its first form made its way from the United States to Great Britain. The British Admiralty realized the power and penetration of its sound, and forthwith adopted it in the navy, operating it by steam instead of by air. At this there arose a great outcry from the mercantile marine. Captains argued that the similarity of the signals confused and often misled them, as they could not tell in the fog whether the sound proceeded from a warship or a lighthouse. The Board of Trade was forced to intervene, but, as it had no jurisdiction over the Admiralty, it sought to extricate itself from an awkward situation by inviting Professor Holmes to perfect a siren which would emit a distinctive sound. His efforts were crowned with complete success.

Fig. 15.—The Fixed (A) and Revolving (B) Parts of the Siren.

Professor Holmes exhibited his wonderful device at the Paris Exhibition of 1867. He installed it in working order, and the visitors displayed an anxiety to hear it. It was brought into action, and those around never forgot the experience. It was the most diabolical ear-splitting noise which had been heard, and, apprehensive that serious results might arise from its demonstration when the buildings were thronged with sight-seers, the authorities refused to permit it to be sounded again. The humorous illustrated papers did not suffer such a golden opportunity to escape. Grotesque and laughable cartoons appeared depicting the curious effects produced by the blast of the instrument, one showing the various statues being frightened off their pedestals proving exceptionally popular.

The siren in its simplest form is an enlarged edition of the “Deviline” toy whistle. There is a Daboll trumpet with a small throat, in which is placed horizontally, not a reed, but a metal disc, so as to fill the whole circular space of the throat. The sheet of metal is pierced with a number of radial slits. Behind this disc is a second plate of a similar character, and likewise pierced with radial slits of the same size, shape and number; but whereas the first disc is fixed, the second is mounted on a spindle. The free disc rotates at high speed, so that the twelve jets of air which are driven through the throat are interrupted intermittently by the blanks of the revolving disc coming over the openings in the fixed disc, while when the two slits are in line the air has a free passage. If the revolving disc completes 3,000 revolutions per minute, and there are twelve slits in the discs, then a total of 36,000 vibrations per minute is produced while the instrument is in operation. The speed of the revolving disc, as well as the number and size of the openings, varies according to the size and class of the siren; but in any case an intensely powerful, dense and penetrating musical tone is emitted, which can be heard a considerable distance away. The blast of a high-powered large siren has been heard at a distance of twenty to thirty miles in clear weather, though of course in thick weather its range is reduced.

While Professor Holmes was experimenting with this device, another investigator, Mr. Slight, of Trinity House, was wrestling with the same problem. Indeed, he may be described as the inventor of the modern siren. Although he effected only an apparently slight modification, it was the touch which rendered the instrument perfect, while it also removed the possibility of a breakdown at a critical moment, as he rendered the moving part freer in its working and eliminated the severe strains to which it was subjected. The improvement was appreciated by Professor Holmes, who adopted it immediately.

While these indefatigable efforts were in progress, ingenious attempts were made to press Nature herself into operation. As is well known, there are many “blowing-holes” distributed throughout the world, where the water by erosion has produced a long, narrow cavern in the base of a rock, with a constricted outlet into the outer air. The waves, rushing into the cave, compress the air within, which, in its escape at high velocity through the small vent, produces a bellowing sound. It was this curious phenomenon which gave the Wolf Rock its name. General Hartmann Bache, of the United States Engineers, attempted in 1858 to make use of a blowing-hole on one of the Farallon Isles, lying forty miles off the entrance to San Francisco Bay. A chimney was built with bricks above the orifice, through which the air compressed by the waves below made its escape, and on top of this shaft a locomotive whistle was placed. The first effort was a dead failure, because the force of the rush of air was so great that it carried away the chimney; but in the second attempt success was achieved, and an excellent automatic whistle blared out night and day almost continuously and was audible for some distance out to sea. The only drawback was that in foggy weather, when the most intense sound was required, the signal was dumb owing to the smoothness of the water. This novel signal was maintained for some time and then was superseded by a powerful siren.

One of the most interesting fog-signalling installations in service is that on the bald formidable hump of rock lying in the estuary of the Clyde, known as Ailsa Craig. For years this rock constituted a terrible menace to the crowded shipping of this important marine thoroughfare, and its victims were numerous. While the Commissioners of Northern Lighthouses mitigated its terrors as far as possible by the provision of a powerful light, they recognized the fact that a visual warning did not meet the situation completely. But the installation of a fog-signal was a somewhat peculiar problem, owing to the configuration of the rock. A single station would not meet requirements, because it was necessary to throw the warning from both sides of the obstruction. The provision of two sound-stations would have been an expensive matter, even if it had been feasible, which it was not, owing to the precipitous nature of the cliffs.

An ingenious solution was advanced by Mr. Charles Ingrey, C.E. He proposed to erect a central power-station and to control the sounding of two sirens, placed on opposite sides of the island, therefrom, the compressed air being led through underground piping. The plans were submitted to Messrs. Stevenson, the engineers to the Northern Lighthouse Board, who, after examining the proposal thoroughly, gave it their approval. But when it came to obtaining the sanction for the requisite expenditure from the Board of Trade, that august body, despite the fact that the project had been investigated and had received the approbation of the engineers to the Northern Lighthouse Commissioners, declined to permit public money to be expended upon an untried scheme. Such is the way in which pioneering effort and ingenuity are stifled by Government departments.

THE ACETYLENE FOG-GUN.

The latest ingenious device for giving both audible and visual warning automatically.

Many another engineer would have abandoned the project after such a rebuff, but Mr. Ingrey without any delay laid down a complete installation upon the lines he contemplated on the island of Pladda, where a Holmes fog-horn was in service. With the aid of a workman whom he took from Glasgow, the light-keepers and some farm labourers, this trial installation was completed, the piping being carried round the island from the air-compressing plant to the fog-signal. The work occupied about a fortnight, and then, everything being ready to convince the sceptical Board of Trade, the inspecting engineers were treated to a comprehensive and conclusive demonstration. They were satisfied with what they saw, appreciated the reliability of the idea and gave the requisite sanction. Forthwith the Ailsa Craig Island installation was put in hand and duly completed.

This plant possesses many ingenious features. As the light is derived from gas distilled from crude oil, a small gas-making plant is installed on the island, and this is used also for driving a battery of five eight-horse-power gas-engines—four are used at a time, the fifth being in reserve—to supply the thirty-horse-power demanded to operate the fog-signal. The energy thus developed drives two sets of powerful air-compressors, the four cylinders of which have a bore of 10 inches by a stroke of 20 inches, the air being compressed to 80 pounds per square inch and stored in two large air-receivers which hold 194 cubic feet. From this reservoir pipes buried in a trench excavated from the solid rock extend to the two trumpets, placed on the north and south sides of the island respectively. The length of piping on the north side is 3,400 feet, and on the south side 2,500 feet. At places where the pipe makes a dip, owing to the configuration of the rock, facilities are provided to draw off any water which may collect. Extreme care had to be displayed in connecting the lengths of piping, so that there might be no leakage, in which event, of course, the pressure of the air would drop and thereby incapacitate the signal.

THE RATTRAY HEAD LIGHTHOUSE.

A very exposed Scottish rock tower. It is unique because a full-powered siren fog-signal is installed therein.

Each signal is mounted in a domed house built of concrete, the mouth of the trumpet extending from the crown of the roof. Within the house is an air-receiver 9 feet in height by 4½ feet in diameter, of about 140 cubic feet capacity, which receives the compressed air transmitted through the piping from the compressing-station. It also contains the automatic apparatus whereby the signal is brought into action at the stipulated intervals, so as to produce the requisite sound characteristic. This is a self-winding clockwork mechanism which admits and cuts off the supply of air to the trumpets, its chief feature being that the clock is wound up by the compressed air itself, so that it is entirely free from human control. However, as a breakdown even with the best-designed and most-carefully-tended machinery cannot be circumvented entirely, there is a duplicate electrical mechanism, also automatically controlled from the power-generating station, the electric cables for which are laid in the pipe trenches. This acts as an emergency control.

By courtesy of Messrs. D. and C. Stevenson.

SULE SKERRY LIGHT.

A lonely light of Scotland. The nearest land is the Butt of Lewis, 30 miles distant.

The two signals are not sounded simultaneously; neither are they alike nor of the same tone. The north signal gives a single blast of high tone, lasting five seconds, and then is silent for 175 seconds. On the south side the siren gives a double note, although there are three blasts—viz., high, low, high—corresponding to the letter R of the Morse code. The notes are sounded for two seconds, with similar intervening periods of silence, and silence for 170 seconds between the groups. The complete signal from the two stations is given once in three minutes, the north signal commencing to sound ninety seconds after the south signal has ceased. The high note corresponds to the fourth E in the musical compass, there being 38,400 vibrations per minute; while the low note is tuned to the third D in the musical compass, with 16,800 vibrations per minute. The notes are purposely timed more than an octave apart and made discordant, as thereby the sound is more likely to attract attention and to be readily distinguished.

About eighteen minutes are required to bring the apparatus into operation—that is, to start compressing and to raise the pressure of the air to the requisite degree—but, as fogs descend upon the Clyde with startling suddenness, the signals may be started within five minutes of the fog-alarm. The air-reservoirs are kept charged to the working pressure, the machinery being run once or twice for a short time every week for this purpose and to keep the plant in working order.

Up to this time it had been the practice to place the siren in close proximity to the air-compressing machinery, but the installation at Ailsa Craig proves conclusively that this is not essential to success; also it demonstrates the fact that a number of signals can be operated reliably and effectively from a central station. Indeed, this Scottish plant aroused such widespread interest that the Pulsometer Engineering Company of Reading, who had acquired Professor Holmes’s patents and who carried out the above installation, received several inquiries from abroad with regard to its suitability for similar situations. In one instance the compressed air was to be transmitted for a distance of nearly four miles.

While the siren has been adopted and found adequate by the majority of nations, the Canadian Government has installed a far more powerful instrument upon the River St. Lawrence, as the ordinary siren signals originally established near the mouth of the river, although of great power, were found to be inadequate. The new apparatus, which is known as the “diaphone,” gives an extraordinarily powerful sound. It comprises a cylindrical chamber, in the walls of which are cut a number of parallel slits. Concentrically disposed within the chamber is a cylindrical hollow piston, with similar slits and a flange at one end, the whole being enclosed in an outer casing. Air under pressure is admitted into the outer casing, and drives the piston backwards and forwards with great rapidity. The result is that the air effects its escape through the orifices, when they come into line, in intermittent puffs.

While the broad principle is not unlike that of the conventional siren, the main difference is that in the latter there is a rotary motion, whereas in the diaphone the action is reciprocating. The great advantage of the latter is that all the vibrations are synchronous, owing to the symmetrical disposition of the slits, and consequently the note produced is very pure. The mechanism is so devised that the piston’s motion is controlled to a nicety, and the sound is constant. Experience has proved that the best results are obtained by using air at a pressure of 30 pounds per square inch. The sound thus produced is intensified to a markedly greater degree by means of a resonator properly attuned.

This instrument has displaced the siren among the stations upon the St. Lawrence River. The general type of apparatus has a piston 4½ inches in diameter, and uses 11 pounds of air per second during the sounding of the blast. But at more important stations a far larger and more powerful class of apparatus is used, the diaphone at Cape Race having a piston 8½ inches in diameter and using 27 feet of air per second while sounding. This does not indicate the limit of size, however, since the builders of this terrible noise-producer are experimenting with an apparatus having a piston 14 inches in diameter. The sound issuing from such a huge apparatus would be almost as deafening as the report of a big gun and should succeed in warning a mariner several miles away.

The atmosphere, however, plays many strange pranks with the most powerful sound-producing instruments. To-day, for instance, a fog-signal may be heard at a distance of ten miles; to-morrow it will fail to be audible more than a mile away. This aberration of sound is extraordinary and constitutes one of the unsolved problems of science. Innumerable investigations have been made with the object of finding the cause of this erratic action, but no conclusive explanation has been forthcoming. Another strange trick is that, while a sound may be audible at distances of two and four miles during a fog, it fails to strike the ear at three miles. It is as if the sound struck the water at a range of two miles, bounded high into the air, and again fell upon the water at four miles, giving a second leap to hit the water again farther on, in much the same way as a thin flat stone, when thrown horizontally into the water, will hop, skip, and jump over the surface. This trick renders the task of the lighthouse engineer additionally exasperating and taxes his ingenuity to the utmost, as it appears to baffle completely any attempt towards its elimination.

Recently another ingenious and novel system has been perfected by Messrs. D. and C. Stevenson. This is an acetylene gun which acts automatically. Hitherto an unattended fog-signal—except the bell-buoy tolled by the movement of the waves, which is far from satisfactory, or the whistling buoy, which is operated upon the same lines and is equally ineffective except at very short range—has found little favour. The objections to the bell and whistle buoys are the faintness of the sounds, which may be drowned by the noises produced on the ship herself; while, if the wind is blowing away from the vessel, she may pass within a few feet of the signal, yet outside its range. Thus it will be recognized that the fog-gun serves to fill a very important gap in connection with the warning of seafarers during thick weather.

As is well known, even a small charge of acetylene, when fired, will produce a loud report, and this characteristic of the gas induced Messrs. Stevenson to apply it to a fog-signal. They have developed the automatic acetylene system of lighting to a very high degree around the coasts of Scotland, and there are now more than twenty lights of this class, mostly unattended, in operation, some of which have been established for many years. These lights have proved highly satisfactory. There has never been an accident, a freedom which is due to the fact that Moye’s system is used, wherein the possibilities of mishap are surmounted very effectively. Accordingly, the engineers saw no reason why a similar system should not be adapted to the emission of sound instead of light signals, or, if desired, of both simultaneously. Their experiments have been crowned with complete success, and, as the gun uses no more gas than would be consumed if a flashing light system were used, the cost of operation is very low.

The general features of the acetylene fog-gun may be observed from the illustration (facing p. [64]). The acetylene, dissolved in acetone, is contained under pressure in a cylinder, and thence passes through a reducing valve to an annular space, where it is ignited by an electric spark. A trumpet is attached to the firing chamber, so that the sound becomes intensified. If desired, the explosion can be effected at the burner, so that, in addition to a sound-signal, a flashing light is given.

The applications vary according to the circumstances. Suppose there is an unlighted bell-buoy at the bar of a port. Here the procedure is to install a gun and light combined, so that the flash of the explosion may give visual and the report audible warning. Or, should there be a lighted buoy already in position, its effectiveness may be enhanced by adding the gun, the detonation alone being employed for warning purposes. The size of the cylinder containing the dissolved acetylene may be varied, so that renewal need only be carried out once in one, two, or more months, according to conditions. If the increasing traffic around a certain rock demand that the latter should be marked, a combined sound and light apparatus can be installed. It may be that the head of a pier which is accessible only at certain times, or a beacon which can be reached only at rare intervals, may require improved facilities. In this case the gun can be set up and a cable laid to a convenient spot which may be approached at all times by an attendant. Then the latter, by the movement of a switch, can bring the gun instantly into action upon the alarm of fog, and it will keep firing at the set intervals until, the fog lifting, the gun is switched off.

In some cases, where the apparatus is set upon a lonely rock, a submarine cable may be laid between the marked point and the control-station. The cable is not a very costly addition. There are many lights where wages have to be paid merely for a man to bring the fog-signalling bell machinery into action. In such cases a fog-gun can be installed and the annual cost of maintenance decreased enormously, thereby enabling the outlay on the gun to be recouped within a very short time; while the light may be improved by using the flashes, so that the warning can be rendered more distinctive.

The invention is also applicable to lightships, many of which are manned by four men or more at a large cost per annum. In the majority of cases an unattended Stevenson lightship—such as described in another chapter, six of which are in use around the coasts of Scotland, and which give, not only a first-class light, but, by the aid of the fog-signal gun, can be made to give an excellent fog-signal as well—offers a means of reducing the heavy maintenance charges arising in connection with a manned light-vessel. In many instances existing lightships can be converted to the automatic system and completed by the gun. Each case must, of course, be decided upon its merits as regards the time the gun and light are required to work upon a single charge of acetylene, but there are no insuperable obstacles to its utilization.

Of course, in an isolated station lying perhaps some miles off the mainland, it may be necessary to keep the gun going night and day in fog and in clear weather alike. In this case, naturally, the great number of explosions involves considerable expense; but the inventors are carrying out experiments with a view to switching the gun on and off, as required, from a distant point by means of wireless telegraphy, so as to effect a saving in the expenditure of acetylene when there is no need on account of fine weather to keep the gun going. Still, it must not be supposed that the detonations even during clear weather are altogether abortive, inasmuch as a sound-signal at sea, where the atmosphere has a long-distance-carrying capacity as a rule, in conjunction with a light, draws double attention to a danger spot. Under such circumstances the waste of acetylene gas during periods of clear weather is more apparent than real.

The contest against the elements is still being waged, and slowly but surely engineering science is improving its position, and is hopeful of rendering audible signals as completely effective as those of a visual character.

CHAPTER V
THE EDDYSTONE LIGHTHOUSE

It is doubtful whether the name of any lighthouse is so familiar throughout the English-speaking world as the “Eddystone.” Certainly no other “pillar of fire by night, of cloud by day,” can offer so romantic a story of dogged engineering perseverance, of heartrending disappointments, disaster, blasted hopes, and brilliant success.

Standing out in the English Channel, about sixty miles east of the Lizard, is a straggling ridge of rocks which stretches for hundreds of yards across the marine thoroughfare, and also obstructs the western approach to Plymouth Harbour. But at a point some nine and a half miles south of Rame Head, on the mainland, the reef rises somewhat abruptly to the surface, so that at low-water two or three ugly granite knots are bared, which tell only too poignantly the complete destruction they could wreak upon a vessel which had the temerity or the ill luck to scrape over them at high-tide. Even in the calmest weather the sea curls and eddies viciously around these stones; hence the name “Eddystones” is derived.

From the days when trading vessels first used the English Channel the reef has been a spot of evil fame. How many ships escaped the perils and dangers of the seven seas only to come to grief on this ridge within sight of home, or how many lives have been lost upon it, will never be known. Only the more staggering holocausts, such as the wreck of the Winchelsea, stand out prominently in the annals of history, but these serve to emphasize the terrible character of the menace offered. The port of Plymouth, as may be supposed, suffered with especial severity.

As British overseas traffic expanded, the idea of indicating the spot for the benefit of vessels was discussed. The first practical suggestion was put forward about the year 1664, but thirty-two years elapsed before any attempt was made to reduce theory to practice. Then an eccentric English country gentleman, Henry Winstanley, who dabbled in mechanical engineering upon unorthodox lines, came forward and offered to build a lighthouse upon the terrible rock. Those who knew this ambitious amateur were dubious of his success, and wondered what manifestation his eccentricity would assume on this occasion. Nor was their scepticism entirely misplaced. Winstanley raised the most fantastic lighthouse which has ever been known, and which would have been more at home in a Chinese cemetery than in the English Channel. It was wrought in wood and most lavishly embellished with carvings and gilding.

Four years were occupied in its construction, and the tower was anchored to the rock by means of long, heavy irons. The light, merely a flicker, flashed out from this tower in 1699 and for the first time the proximity of the Eddystones was indicated all round the horizon by night. Winstanley’s critics were rather free in expressing their opinion that the tower would come down with the first sou’-wester, but the eccentric builder was so intensely proud of his achievement as to venture the statement that it would resist the fiercest gale that ever blew, and, when such did occur, he hoped that he might be in the tower at the time.