Littell's Living Age/Volume 139/Issue 1795/Lighthouses
LIGHTHOUSES .
Lighthouses are of great antiquity, but were long of a very imperfect kind; originally nothing more than open fires on the ground. Faraday says that the first idea of a lighthouse was the candle in the cottage window, lighting the husband across the water, or the pathless moor. At an early period in the history of commerce the necessity for such structures must have been felt, and the ancients paid great attention to their construction. The most celebrated lighthouse of antiquity was that of Pharos, near Alexandria, built by Ptolemy Philadelphus, b.c. 280. Josephus states that its light could be distinguished at forty-five miles distance; it fell so recently as a.d. 1303. From this building pharos came to be the general name for lighthouse, and still exists in the French phare.
The Romans were diligent builders of lighthouses, and were the first to introduce them into England. On the summit of Dover Mount still stands the Roman pharos which is supposed to have lighted vessels from the coast of France. Authentic records have come to us of lighthouses at Ostea, Caprea, Ravenna, Puteoli, at the mouth of the Chrysorhoas, on the Bosphorus, Boulogne; and Pennant gives a plate of what is supposed to have been a Roman tower at Gaireg, in Wales.
During the Middle Ages many such towers were erected, the most beautiful of which, as an architectural structure, is that of Genoa. The old English towers were rough and homely, and Lambarde describes them before the reign of Edward III. as "merely great stacks of wood."
The general management of lighthouses and buoys in England is entrusted to the Corporation of the Elder Brethren of the Holy and Undivided Trinity, known as Trinity House. This body was first incorporated in the year 1515, in the reign of Henry VIII., but for many years little was done to ensure the safety of ships by means of lights. With the increase of commerce and navigation, however, they became a matter of necessity, and in the time of James I. the first lighthouse was erected on Dungeness Point.
The first stone lighthouse in Europe was the celebrated Tour de Condouran, built on a flat rock off the mouth of the Garonne, in the Bay of Biscay. It was finished and lit up more than two hundred and fifty years ago, but still continues one of the finest towers in existence; it replaced one built by the English between 1362-71, when the Black Prince was governor of Guienne. The stone building was begun by Louis de Foix in 1584, continued through the reign of Henry IV., and finished in that of Louis XIII. Its height is now one hundred and eighty-six feet, and its style of construction enables it to bear much more decoration than our own more homely structures; it is also memorable as the first house which exhibited a revolving light.
Perhaps the most familiar and celebrated of all lighthouses is that of Eddystone, which marked a crisis in the history of lighthouse building, for the marvellous success which attended its erection led to many other works of the same kind. The Eddystone forms the crest of a reef of rocks which rise fourteen miles S.S.W. of Plymouth Harbor; they are nearly in a line with Lizard Head and Start Point, and lie in the very path of vessels coasting up and down the English Channel; many a gallant ship has been dashed to pieces, and its sailors gone down within sight of home, on this cruel rock. The first attempt to establish a light upon it was made by Mr. Winstanley, who obtained the necessary powers in 1696, and finished his honorable undertaking in four years, though the light was first exhibited in 1698. The rock being uncovered only at low water and in calm weather, rendered the undertaking one of extreme difficulty, and the first summer was entirely spent in making twelve holes in the rocks, and fastening irons into them by which to hold the superstructure; sometimes for ten or twelve days together, the violence of the eddying sea would prevent all operations. The work of the second summer was the erection of a solid pillar on which to set the lighthouse; and during the third, it rose to a height of eighty feet. The fourth summer saw the completion of what resembled a Chinese pagoda, with open galleries and numerous projections; the main gallery under the light was so wide that an eye-witness recorded that it was "possible for a six-oared boat to be lifted up on a wave, and driven clear through the open gallery into the sea on the other side." Winstanley deserves every credit for his heroic endeavor to accomplish what had hitherto been deemed impossible, but a building so unsuited in every way to endure the violence of winds and waves could not stand, and we are not surprised to hear that, during a violent storm in November, 1703, it was entirely washed away, though we must regret that its brave erector perished in the fall of his own creation.
Three years after this failure, in 1706, the Brethren of Trinity House obtained an act of Parliament to enable them to rebuild the lighthouse, and the lease being taken by Captain Lovet, he entrusted the work to John Rudgood, who designed a simple and masterly tower which, avoiding the projections of its predecessor, offered as little resistance as possible to the elements; it was erected in the form of a cone, but its main defect lay in the material of which it was composed, for, like Winstanley's, it was of wood. It would take too long to follow the details of a building which was then considered a triumph of engineering skill: it is sufficient to say it stood bravely for fifty years and fell a victim to fire in 1755; the flames spread with rapidity through the dry and heated lantern, and in a few minutes the whole building was in ablaze. As the increasing trade in the Channel impelled its re-erection, the proprietors took at once the necessary steps for the work, and casting around for the best man their choice fell upon John Smeaton, whose name will ever live in connection with one of the proudest triumphs of human skill and patience. He was by profession a mathematical-instrument maker, and the matter in hand was wholly new to him, but he lost no time in devoting all his energies to it.
One of his first conclusions was, that the building must be of stone, thus combating the popular impression that "nothing but wood could possibly stand on the Eddystone." He carefully examined the plans of the two former lighthouses, and became more and more convinced that their defect was want of weight; he therefore resolved to make his building solid up to a certain height and from thence hollow, and greatly to increase the diameter of the foundation, taking for his model the bole of a spreading oak-tree; he also made very extensive use of the process of dovetailing, then unknown in masonry, and rooted his foundations into the rock. His plans were made before he ever visited the scene of his future labors, but so skilfully were they laid that slight modifications only were needed. Nothing could bring before us more vividly the almost superhuman difficulties of this undertaking than the account of Smeaton's first attempts to land on the Eddystone rock. Day after day a storm kept him on shore, and when he did reach his destination the sea was so violent that to effect a landing was impossible. This was not the history of one but repeated trials, and we must ever honor the man who, by his patient perseverance, won so noble a victory over the greatest obstacles that nature in her angriest mood could lay in his path.
It was determined that the lighthouse should be built of stone, and all arrangements having been made, Smeaton himself fixed the centre and laid down the lines on August 3rd, 1756, and from that date the work proceeded steadily but intermittently, depending greatly on tide and weather; at the most not more than six hours' labor could be done at one time. By the end of November the necessary cutting in the rock had been safely accomplished, and the workers returned to shore to prepare the stone for next season. The building was fairly begun in the summer of 1757, and, as soon as the work had been carried above high water, it proceeded rapidly. Next season the task was recommenced in May, and to the engineer's delight he found that the storms of winter had left the tower unscathed. This season saw the completion of the solid portion of the building, which formed the floor of the storeroom — the first of the necessary rooms for the lighthouse keepers: the walls of these rooms are twenty-six inches thick; the blocks of stone "joggled and cramped, so as to secure perfect solidity." All through these anxious months Smeaton's sole thought was for his lighthouse, and early in the morning and late at night would he gaze eagerly through his telescope from Plymouth Hoe, till the tall white pillar of darting spray assured him of the safety of his cherished undertaking, every portion of which had been manufactured under his own eye. The next season proved so stormy that the men did not begin their work till July; but, so rapidly did it now progress, that by August 17th the last stone was set, and on October 16th, 1759, that light was first exhibited which for more than a century has been a source of joy and safety to the tempest-tossed sailor. The Eddystone lighthouse is ninety feet high, and its light is visible for nine miles, and is now only one of the many beacons which light up the English Channel along its whole extent, and render its navigation as safe by night as by day.[1]
Eleven miles from the mainland of Scotland, near the entrances of the Firths of Forth and of Tay, lies a dangerous reef, which, so early as the fourteenth century, was a source of such peril that the Abbot of Arbroath caused a bell to be placed on what is now so well known as the Bell Rock. In 1799 a more than usually violent storm, which caused a,terrible loss of life, gave rise to the formation of many plans for a lighthouse on the fatal spot, and Captain Brodie proposed one of cast iron, but his idea was not approved of. Other plans were also proposed and rejected, till the commissioners appointed Mr. Rennie to examine the site, and report as to the best course to be pursued. After much deliberation he decided that a stone lighthouse, built on the plan of Eddystone, would alone meet the exigencies of the case; the rock being uncovered by the water for less time than that of Eddystone, the difficulties of the foundation would be even greater, but he had no doubt they could be overcome and the work accomplished in four years. The report was adopted, and Mr. Rennie appointed chief engineer, with Mr. Stevenson as assistant, to superintend operations on the spot, and in 1807 the task was begun.
It is impossible in one short paper to follow in detail the difficulties, disappointments, and slow progress of the building of each lighthouse, which were much the same in every case, varied only by the greater or less hindrances of tide and site. The history of the Bell Rock lighthouse rivals in thrilling interest that of Eddystone, and should be read by all who can sympathize with the daring yet patient ardor of our great engineers. We must be content to say that it was happily completed by the end of 1810, and the light regularly exhibited after February 11th, 1811. Its cost was £61,332; its height, one hundred and seventeen feet, and its light can be seen for a distance of eighteen miles.
Another celebrated Scotch lighthouse, to which a brief notice must be accorded, is that of Skerryvore, twenty-four miles west of Iona. It is the chief rock of a long reef of compact gneiss, which stretches for eight or ten miles, and in the only point which could afford the needful foundation; for forty-four years previous to 1844 it had been annually the scene of a shipwreck. The difficulty of landing was great, owing to the immense force (three tons to the superficial foot) with which the Atlantic broke upon it, and caused the delay of the scheme till 1838, when it was undertaken by Mr. Alan Stevenson, who followed generally the plan of the Bell Rock, and, in spite of disasters and tempests, completed his work in 1844. Its cost was nearly £87,000; its diameter at the base, forty-two feet, and at the top, sixteen feet; and its light is a guide to mariners for eighteen miles.
The total number of lights in Great Britain in January, 1871, afloat and ashore, was five hundred and fourteen. Lighthouses in England are usually painted white or red, while those in Scotland are left their natural color. The number of lights of all classes on the English coast averages one to nearly every eleven miles; or, if the floating lights are excluded, one to every fourteen miles; as a general rule, the horizon to be lighted is limited to fifteen or twenty miles, and the height above the sea level varies from ninety to five hundred and forty feet; depending, of course, on the situation of the foundation.
The French lighthouse system is very perfect and comprehensive; the authorities class their lights in four divisions, according to their power and range of visibility. The phares of the first class are visible for thirty, those of the second for twenty-five, those of the third for fifteen miles; while the fourth class, or harbor lights, are seen only for six miles. Of thirteen of the principal French lighthouses, the height varies from one hundred and fifty-seven to three hundred and ninety-seven feet, and the cost from £4,000 to £38,000; while the range of visibility is from eighteen to twenty-seven miles. The greatest recorded distance at which an oil lamp has been seen is that of the holophotal light of Allepey, in Travancore, which has been visible from an elevated position forty-five miles away. This seems very wonderful, but is almost equalled by the revolving light of Buccalieu, in Newfoundland, which throws its beneficent beams for forty nautical miles.
Something must now be said on the subject of the lights themselves, which, beginning with the old-fashioned beacon fires, have not yet reached perfection. The earliest system was merely that of blazing fires on the open ground; then a candle was tried placed in a lantern, and this was adopted at Eddystone, which was first lighted by twenty-four candles in a sort of chandelier. The use of oil lamps instead of candles is said to have been introduced by the celebrated engineer Borda, about 1780 or 1790. Various kinds of oil have been tried; for fifty years spermaceti was used, but the preference is now given to rape-seed, or colza, as the most economical and reliable.
The next step in advance was the adoption of reflectors, which gave rise to the catoptric system, which was universal for half a century. The light thrown from a parabolic reflector is sent out in parallel rays, and can be seen for a great distance. Then came the dioptric system, which consisted in magnifying one large flame through a lens. It had been suggested to Smeaton, 1759, and had been actually employed in the Portland lighthouse in 1789, but, through some mismanagement, it had fallen into disfavor for many years till revived by Augustin Fresnel in a paper read before the French Academy of Sciences, in 1822. The French government at once adopted the dioptric system, which has been improved and perfected by Leopold Fresnel, Alan Stevenson, Arago, and Faraday; it is to this last-named distinguished philosopher that we are indebted for the present efficient mode of ventilating lighthouse lamps.
The light now generally adopted in British lighthouses is a mixture of the two systems; inside the great glass lantern, usually about twelve feet high, is placed another framework of glass, corresponding to the shape of the lantern, and which, enclosing the lamp, is composed of, firstly, a band of glass round the middle, called the lenticular belt, which considerably magnifies the flame; the top consists of a number of prisms, which intercept the light which would otherwise be lost on the roof; and in the lower part of the apparatus is another set of prisms, which, in a similar manner, prevent the light being wasted below.
A curious light is one shown at Stornoway Bay, where the position of a rock is indicated by means of a beam of parallel rays thrown from the shore upon an apparatus fixed in the top of a beacon erected upon the rock itself; this is called an apparent light, from its appearing to rise from a flame on the rock, while in reality it proceeds from the shore six hundred and fifty feet distant, and is refracted by glass prisms placed on the beacon.
Many other means of lighting, besides that of oil lamps, have been tried, though none of them are yet extensively adopted; lime light, electric light, magnesium, and gas. Sir William Thomson, however, considers that "the lighthouse of the future is to be illuminated by gas, except when the situation is on an isolated rock, or where, for any reason, the price of coal is prohibitory." Professor Tyndall coincides in this opinion, and in a paper by Mr. Wigham, gas engineer, we find that this theory has been put into practice by the Irish Board of Lights at Howth Bailey, in Dublin Bay, where an actual saving has been effected by the substitution of gas for oil. The most beautiful and interesting, perhaps, of all lights, is that discovered by Professor Faraday, the electric light. It is really nothing more than the white heat caused by the meeting of two opposing electrical currents, generated by a powerful machine, and conveyed by two copper wires, each terminating in a carbon point. These points are kept at a certain distance from each other, and when the two opposing currents meet there, the resistance of both causes the carbon to glow and become white hot; the incandescent state of the carbon is the brilliant electric light itself. It was utilized by Mr. Holmes, who invented an apparatus for producing it, which was tried in 1859 at the South Foreland lighthouse; it has, however, only been steadily used for six years, but has proved itself so successful that it merits a somewhat detailed notice. The stream of electricity which supplies the two lighthouses standing one above the other on the chalk cliffs of the South Foreland promontory, is not derived from a pile or a battery, but is ground out of huge magneto-electric machines worked by a twenty horse-power steam engine — the current being conducted by wires from the machine-house to the lighthouses. The light generated by this beautiful contrivance is kept constant by means of a clockwork arrangement which draws the carbon points closer together as they disperse themselves by combustion; it is necessary, however, to change them-altogether every three hours, but as this is accomplished by the keeper in a few seconds, no real inconvenience is experienced. The cost is a more serious consideration, for we are told, while three keepers suffice for an ordinary lighthouse, a staff of eight men is constantly needed to sustain the electric light at the South Foreland.
A large majority of lights on the British coast are fixed, but a considerable number are revolving. Sir William Thomson considers the present system of lighting very far from perfect, and would have all lighthouses so distinguished that they could not possibly be mistaken for ship or shore lights. He recommends the abolition of lights revolving at different intervals, which, he says, are often mistaken on a stormy night, and the adoption of Morse's telegraph signs. Each lighthouse should have its own letter, which it should show incessantly from sunset to sunrise by means of Morse's dots and dashes, this being accomplished by a simple mechanical contrivance which would drop a screen before the gaslight, eclipsing it at intervals, thus by light and darkness showing the letters on Morse's plan; the length between the dots and dashes indicated by intervals of darkness, the dots and dashes themselves, that, is the letters, by short and long flashes; this is called an occulting light. The originator of this idea was Babbage the mathematician, and his paper on the subject maybe found by the curious in the pigeon-holes of Trinity House, though warmly approved of by such high authorities as Professor Tyndall and Sir William Thomson, the latter of whom has invented an eclipsing gaslight to be employed in lighthouses, which was exhibited at a conversazione of telegraph engineers on December 2nd, 1874.
This branch of scientific discovery is, like so many others at the present day, still capable of further development, and the perfection and extension of the labors of our savants will doubtless furnish a theme of interest to the future historian of scientific research, and its practical application to the wants of commercial navigation. A. G.
- ↑ Since these words were written it has been discovered that the foundations of the Eddystone Lighthouse have commenced to give way. The lighthouse is consequently condemned. It was at first proposed to destroy the rock on which it stands by dynamite; but there appears to have been some objection to this plan: and the present lighthouse will probably give place to a new and still more perfect structure.