[Ill.u.s.tration: HOLOPHOTAL REVOLVING LIGHT. (FIRST ORDER) FLOATING LIGHT LANTERN. HOLOPHOTAL REVOLVING LIGHT. (FOURTH ORDER.) REVOLVING LIGHT APPARATUS.
(_From Drawings supplied by Messrs. W. Wilkins & Co._)]
Alan Stevenson states that the earliest notice he has been able to find of the application of paraboloidal mirrors to lighthouses is in a work on "Practical Seamanship" (Liverpool, 1791), by Mr. William Hutchinson, who notices the erection of the four lights at Bidstone and Hoylake for the entrance of the Mersey, in 1763, and describes large paraboloidal moulds of wood lined with mirror gla.s.s and smaller ones of polished tin-plate, as in use in those lighthouses. In France M. Teulere, a Member of the Royal Corps of Engineers of Bridges and Roads, is regarded as the inventor of the catoptric system of lights. In a memoir dated 26th June, 1783, he is said to have proposed for the Cordouan Lighthouse a combination of paraboloidal reflectors with Argand lamps, arranged on a revolving frame, a plan which was actually carried into execution, under the direction of the Chevalier Borda.(60) The plan was so successful that it was soon adopted in England by the Trinity House of London; and in Scotland the first work of the Northern Lights Board, in 1787, was to light a lantern on the Old Castle of Kinnaird Head, in Aberdeenshire, by means of parabolic reflectors and lamps. These reflectors were formed of facets of mirror-gla.s.s placed in hollow paraboloidal moulds of plaster. The more complicated arrangement of lenses placed round a centre in concentric circles is due to the great Fresnel, a practical man of science, whose abilities are acknowledged as fully in England as in France.
The oil used in the lighthouses of the United Kingdom has generally been sperm. Colza, the expressed oil of the wild cabbage (_Bra.s.sica oleracea_), was very generally used in France, and occasionally in Great Britain. Gas is used in a few places, where its application is easy. There can hardly be any doubt now, however, that the coming light will be the electric, since its steady production is becoming a matter of scientific certainty.
As early as 1857 Professor Holmes submitted to the Trinity House a method of employing this light, which was submitted to Faraday, and approved. The Board then allowed a trial at the South Foreland Lighthouse. The light was first displayed on the 8th of December, 1858. In June, 1862, it was permanently fixed at Dungeness. In Faraday"s Report to the Trinity House, published in 1862, he says: "Arrangements were made on sh.o.r.e by which observations could be made at sea, about five miles off, on the relative light of the electric lamp and the metallic reflectors with their Argand oil-lamps, for either could be shown alone, or both together. At the given distance the eye could not separate the two lights, but by the telescope they were distinguishable. The combined effect was a glorious light up to five miles; then, if the electric light was extinguished, there was a great falling off in the effect, though, after a few moments" rest to the eye, it was seen that the oil-lamps and reflectors were in their good and proper state. On the other hand, when the electric light was restored, the glory rose to its first high condition.... During the day-time I compared the intensity of the light with that of the sun, and both looked at through dark gla.s.ses. Its light was as bright as that of the sun, but the sun was not at its brightest."
The number of lights on a well-frequented coast being considerable, it is of the utmost importance to arrange them so as to enable the mariner easily to distinguish them from each other. Catoptric lights admit of nine separate distinctions:-1, fixed; 2, revolving white; 3, revolving red and white; 4, revolving red with two whites; 5, revolving white with two reds; 6, flashing; 7, intermittent; 8, double fixed lights; 9, double revolving white lights. Mr. Stevenson thus defines their distinctive features:-"The first exhibits a steady and uniform appearance which is not subject to any change, and the reflectors used for it are of smaller dimensions than those employed in revolving lights. This is necessary in order to permit them to be ranged round the circular frame, with their axes inclined at such an angle as shall enable them to illuminate every point of the horizon. The _revolving_ light is produced by the revolution of a frame with three or four sides, having reflectors of a larger size grouped on each side with their axes parallel, and as the revolution exhibits once in two minutes or once in a minute, as may be required, a light gradually increasing to full strength and in the same gradual manner decreasing to total darkness, its appearance is extremely well marked. The succession of red and white lights is produced by the revolution of a frame whose different sides present red and white lights, and these afford three separate distinctions, namely, alternate red and white, the succession of two white lights after one red, and the succession of two red lights after one white light. The flashing light is produced in the same manner as the revolving light; but, owing to a different construction of the frame, the reflectors on each of eight sides are arranged with their rims or faces in one vertical plane, and their axes in a line inclined to the perpendicular. A disposition of the mirrors, which, together with the greater quickness of the revolutions, which shows a flash once in five seconds of time, produces a very striking effect, totally different from that of a revolving light, and presenting the appearance of the flash alternately rising and sinking, the brightest and darkest periods being but momentary; this light is further characterised by a rapid succession of bright flashes, from which it gets its name. The intermittent light is distinguished by bursting suddenly into view and continuing steady for a short time, after which it is suddenly eclipsed for half a minute. Its striking appearance is produced by the perpendicular motion of circular shades in front of the reflectors, by which the light is alternately hid and displayed. This distinction, as well as that called the flashing light, is peculiar to the Scotch coast. The double lights (which are seldom used except where there is a necessity for a _leading_ line, as a guide for taking some channel or avoiding some danger) are generally exhibited from two towers, one of which is higher than the other. At the Gulf of Man a striking variety has been introduced into the character of leading lights, by subst.i.tuting for two fixed lights two lights which revolve in the same periods and exhibit their flashes at the same instant; and these lights are of course susceptible of the other variety enumerated above, that of two revolving red and white lights, or flashing lights, coming into view at equal intervals of time. The utility of all these distinctions is to be valued with reference to their property of at once striking the eye of an observer and being instantaneously obvious to strangers. The introduction of colour as a source of distinction is necessary in order to obtain a sufficient number of distinctions; but it is in itself an evil of no small magnitude, as the effect is produced by interposing coloured media between the burner and the observer"s eye, and much light is thus lost by the absorption of those rays which are held back in order to cause the appearance which is desired. Trial has been made of various colours, but red, blue, and green alone have been found useful, and the two latter only at distances so short as to render them altogether unfit for sea-lights. Owing to the depth of tint which is required to produce a marked effect, the red shades generally used absorb from four-sevenths to five-sixths of the whole light-an enormous loss, and sufficient to discourage the adoption of that mode of distinction in every situation where it can possibly be avoided. The red gla.s.s used in France absorbs only four-sevenths of the light, but its colour produces, as might be expected, a much less marked distinction to the seaman"s eye. In the lighthouses of Scotland a simple and convenient arrangement exists for colouring the lights, which consists in using chimneys of red gla.s.s, instead of placing large discs in front of the reflectors."
The construction of the lantern is a point of importance; and one of the first order will cost about 1,260. On the level of the top of the lower gla.s.s a narrow gangway is usually built for the keeper to stand upon in order to clean the panes, an operation which in snowy weather may have to be frequently repeated during the night. At some of the lighthouses on the Mediterranean the lantern is at certain seasons so completely covered with moths as to obscure the light and to require the attendance of men with brooms. Mr. Tomlinson was informed by the keepers at the Eddystone that bees and other insects were much attracted by the light, and collected round the lantern in great numbers. Larks and other birds flew against it, and, becoming stunned with the blow, were picked up on the balcony and were cooked by the men for breakfast. The lantern is very liable to injury in high winds, or the gla.s.s may be broken by large sea-birds coming against it on a stormy night, or by small stones violently driven against it by the wind. Extra plates of gla.s.s are always kept to take the place of broken panes. The number of light-keepers employed varies, ranging from two to four, and in the latter case one is usually allowed to remain on sh.o.r.e, the men taking the privilege in turns. When the situation admits, it is usual to have the keeper"s rooms in a building outside the lighthouse to avoid dust, which is most injurious to the delicate apparatus of the light-room. Great cleanliness is enforced in all that belongs to a lighthouse, the reflectors and lenses being constantly burnished, polished, and cleansed.
And so we have traced the history and progress of lighthouses, and it is hard to believe that any great change can be advantageously made in their construction, though their mode of illumination will doubtless be greatly improved. As we have seen, the electric light was used practically in a lighthouse long before it was in the streets of the great metropolis, and not in a merely experimental way, but with the most successful results.
[Ill.u.s.tration: BREAKWATER AT VENICE.]
CHAPTER XIII.
THE BREAKWATER.
Breakwaters, Ancient and Modern-Origin and History of that at Cherbourg-Stones Sunk in Wooden Cones-Partial Failure of the Plan-Millions of Tons dropped to the Bottom-The Breakwater Temporarily Abandoned-Completed by Napoleon III.-A Port Bristling with Guns-Rennie"s Plymouth Breakwater-Ingenious Mode of Depositing the Stones-Lessons of the Sea-The Waves the Best Workmen-Completion of the Work-Grand Double Breakwater at Portland-The English Cherbourg-A Magnificent Piece of Engineering-Utilisation of Otherwise Worthless Stone-900 Convicts at Work-The Great Fortifications-The Verne-Gibraltar at Home-A Gigantic Fosse-Portland almost Impregnable-Breakwaters Elsewhere.
A breakwater, we are told on the highest authority, is an obstruction of wood, stone, or other material, as a boom or raft of wood, sunken vessels, &c., placed before the entrance of a port or harbour, or any projection from the land into the sea, as a mole, pier, or jetty, so situated as to break the force of the waves and prevent damage to shipping lying at anchor within them. Thus the piers of the ancient Piraeus and of Rhodes; the moles of Venice, Naples, Genoa, and Castellamare; the piers of Ramsgate, Margate, Folkestone, Howth, and the famous wooden dike thrown across the port of Roch.e.l.le. The term, of late years, has been almost exclusively applied to insulated dikes of stone. Of this description of dike for creating an artificial harbour on a grand scale, Cherbourg, Plymouth, and Portland present leading examples. The former, already mentioned in this work, claims our attention.
The French, happily our good friends to-day, were not always so, and there was a period when the splendid natural harbours, bays, and roadsteads of this country were a source of annoyance to them. While nature had been more than kind to us, their coast presented a series of sandy sh.o.r.es, intermingled with iron-bound coasts, bristling with rocks. De Vauban, the great engineer, was employed by Louis, the _Grand Monarque_, to inspect the Channel sh.o.r.es of France, and his natural sagacity and great knowledge caused him at once to select Cherbourg as one of the best points for forming an artificial harbour, protected by suitable fortifications. Other engineers recommended the same port, and one, M. de la Bretonniere, proposed that a number of old ships should be loaded with stones and sunk, while a large quant.i.ty of stone should be also thrown around them to form a grand breakwater, which should rise fifty feet from the bottom. This idea was abandoned, as it appears, partly from the fact that France had not old vessels enough to spare for the purpose, and that it would cost too much to purchase them from foreign nations.
In 1781 an eminent French engineer proposed that, instead of one continuous breakwater, a number of large ma.s.ses or congregations of stones, separated from each other on the surfaces but touching at the bases, should be built on the sea bottom, believing that they would break the force of the waves almost equally well. As a part of his plan he suggested that they should be sunk in large conical _caissons_ of wood, 150 feet in diameter at the base and sixty feet broad at the top. These wooden cones were practically to bind and keep the stones together. They were to be floated to the site with a number of empty casks attached as floats, then detached, filled with stones, and sunk. An experiment at Havre having been considered satisfactory, the Government accepted the idea, and ordered that operations should be immediately commenced at Cherbourg. A permanent council was appointed, as were officers and engineers. In 1783 barracks and a navy-yard were built, and at Becquet, a short distance from Cherbourg, an artificial harbour, capable of holding eighty small vessels for the transport of the stone, was literally dug out.
On June 6th, 1784, the first cone was floated to its destination, and a month later a second was similarly conveyed, in the presence of 10,000 spectators. Before the latter could be filled with stones a storm, which lasted five days, half demolished it. In the course of the summer and autumn not less than 65,000 tons of stone were deposited in and around the cones. In 1785 several more cones were completed and sunk; at the end of the year the quant.i.ty of stone deposited amounted to a quarter of a million tons, and at the end of 1787 a million tons. At the end of 1790, when the works had been seven years in progress and the Government was getting very tired of the whole matter, between five and six million tons of stone had been dropped into the sea. M. de Cessart, the engineer, found that, in order to sink five cones per annum, he had to employ 250 carpenters, 30 blacksmiths, 200 stone-hewers, and 200 masons.
One could hardly expect much permanency from a wooden covering sunk into the sea, and it is not surprising that, one by one, they burst, few lasting more than a year. The outbreak of the Revolution put an end, for some time, to the operations at Cherbourg.
When the construction of the Cherbourg breakwater was resumed, the wooden cone system was abandoned, and the stone was simply sunk from vessels of peculiar construction. The breakwater was completed under Napoleon III., at a cost exceeding two and a half million pounds sterling. The actual breakwater itself was finished in 1853,(61) but since that time most important fortifications have been constructed on the upper works. This is the greatest breakwater in the world, its length being nearly two and a half miles; it is 300 feet wide at the base and 31 at the top. The water-s.p.a.ce shut in and protected is about 2,000 acres, much of this great area being, however, too shallow for very large vessels.
Taken in connection with the fortifications, this breakwater has a value greater than any other in the world. At the apex of the angle formed by the junction of the two branches of the breakwater there is a grand fort, and it bristles generally with batteries and forts, as indeed does Cherbourg generally. Dr. W. H. Russell wrote of it, in our leading journal in 1860 that, "Wherever you look you fancy that on the spot you occupy are specially pointed dozens of the dull black eyes from their rigid lids of stone." With its twenty-four regular forts and redoubts, not including those on the mole, floating harbours, building slips, navy-yards, a.r.s.enals, and barracks, Cherbourg is a most formidable place.
[Ill.u.s.tration: CHERBOURG, FROM THE SEA.]
In England Rennie"s great Plymouth breakwater is the most remarkable specimen, among many others. Its dimensions are not as great as that of Cherbourg, but it was, nevertheless, a vast undertaking. It consists of an immense number of blocks of stone thrown into the Sound, and forms a barrier nearly a mile in length above the surface of the water. This grand work was commenced in 1812, and by the end of the second year about 800 yards of the breakwater began to appear at low water, and the swell was so much broken that ships of all sizes began to take shelter behind it; while the fishermen within its shelter could not judge accurately of the weather outside the Sound, so great was the change. Several limestone quarries near the Cat.w.a.ter were purchased of the Duke of Bedford for 10,000, and some fifteen vessels were constantly employed in removing the blocks, which ranged in weight from one to ten tons. These vessels were of ingenious construction; they had two railways laid along them parallel to each other, with openings in the stern to admit the cars or trucks laden with stones. These were wheeled from the quarry to the quay, and so on to the vessels, till the lines of rails were filled with trucks. The vessels then proceeded to the works, each bearing its load of stone-laden trucks.
On reaching the breakwater each truck was wheeled to the opening, and the stones tipped into the sea. During the first five years the amount of stone deposited gradually rose from 16,000 to 300,000 tons per annum. The large ma.s.ses were first lowered, and then smaller stones, quarry rubbish, &c., to fill up the interstices. The structure was completed in 1841, with the use of 3,670,444 tons of stone(62) and at a cost of something like a million and a half of money. A distinguished French engineer, M. Dupin, who visited the works during their progress, describes in glowing terms the admirable arrangements, the order and regularity visible in all the proceedings. "Those enormous ma.s.ses of stone," he remarks, "which the quarrymen strike with heavy strokes of their hammers; and those aerial roads of flying bridges, which serve for the removal of the superstratum of earth; those lines of cranes, all at work at the same moment; the trucks, all in motion; the arrival, the loading, and the departure of the vessels, all this forms one of the most imposing sights that can strike a friend to the great works of art. At fixed hours the sound of a bell is heard, in order to announce the blasting of the quarry. The operations instantly cease on all sides; all becomes silence and solitude. This universal silence renders still more imposing the noise of the explosion, the splitting of the rocks, their ponderous fall, and the prolonged sound of the echoes."
"The waves," said Rennie, "were the best workmen" in the construction of a breakwater of rough stones, and on the whole his belief was confirmed, for the storms by which his great work was a.s.sailed rather helped than hindered it, by showing the most desirable slope on the sea-side, while comparatively little damage was done. The slope of the stone barrier was, however, by their force changed very greatly. An inclination of three to one was altered to about five to one, and Rennie had recommended that the authorities should take a lesson from nature and finish the breakwater according to her teachings. "It would appear," says Mr. Smiles,(63) "that Mr. Whidbey, the resident engineer, contrived to finish most of the exterior face at a slope of only three to one, as before; and that it stood without any material interruption until several years after Mr.
Rennie"s death. By that time nearly the whole of the intended rubble, amounting to 2,381,321 tons, had been deposited, and the main arm, with 200 yards of the west arm, making 1,241 yards in length, had been raised to the required level. The work had arrived at that stage when it had to experience the full force of another terrific storm, which took place on the 23rd of November, 1824. It blew at first from the south-south-east and then veered round to the south-west, and the effect of this concurrence of winds was to heap together the waters of the Channel between Bolt Head and Lizard Point, and drive them, with terrific force, into the narrow inlet of Plymouth Sound. This storm was not only greatly more violent, but of much longer duration than that of 1817. When the breakwater could be examined it was found that out of the 1,241 yards of the upper part, which had been completed with a slope of three to one, 796 yards had been altered as in the previous storm, and the immense blocks of stone which formed the seaface of the work had, by the force of the waves, been rolled over to the landward sides thus reducing the sea-slope, as before, to about five to one. The accuracy of Mr. Rennie"s view as to the proper slope-which was indicated by the action of the sea itself-was thus a second time confirmed;" and a board of eminent engineers reporting in accordance, the work was so finished. When the action of the sea had formed its own slope and had wedged together and settled the great ma.s.s of materials which form the breakwater, and when no further movement was apparent, but the whole appeared consolidated together, then the slope towards the sea was cased with regular courses of masonry, dove-tailed and cramped together, the diving-bell being brought into requisition for placing the lower courses. A lighthouse has been erected on its western extremity, and the work may be regarded as a magnificent success, worthy of a great maritime nation.
A third leading ill.u.s.tration of a magnificent breakwater is afforded at Portland, and it is deserving of particular mention inasmuch as all authorities agree that it was constructed with little or no waste of the public money. "In the mind of the inquiring tax-payer," said our leading journal,(64) "breakwaters are always a.s.sociated with millions of money thrown broadcast into the sea, in out-of-the-way bays and inlets, which even without these obstacles to make them more dangerous, the most distressed mariner would be particularly careful to avoid;" and the writer goes on to mention several which either ought not to have been attempted, or where extravagant expenditure has been incurred. "In such a woeful list of hideous failure and costly mismanagement, it is a comfort to perceive that the long lane begins to turn at last, and that from our now having one good standard to go by, we may hope for better things for the future.
Portland breakwater is a really grand and magnificent work, and one of which the nation may well be proud if it is inclined to let bygones be bygones, and forget the many successive failures before it was able to attain so much." Portland breakwater is the right construction in the right place, and before its erection the Roads afforded doubtful shelter to vessels in distress. One advantage it enjoys, that of possessing a splendid anchorage of stiff blue clay, and being free from rock or shoal from the island of Portland itself up to the very esplanade of Weymouth.
There, too, was the stone on the very spot; steep and rugged heights for fortifications, a n.o.ble harbour for shipping, and rail communication with all parts. But all these advantages might have been ignored but for the formidable nature of the works constructed at Cherbourg. The port itself is about five hours" steaming from the French Cronstadt it was designed, _sub rosa_, to keep an eye upon. So, in 1844, the commissioners recommended that it should be made a grand fortified naval station. In 1847 an Act was pa.s.sed authorising the construction of a breakwater, and in 1849 the foundation-stone was laid by the Prince Consort.
[Ill.u.s.tration: PORTLAND.]
Nature has provided, in the mighty bank known as the Chesil Beach, practically a great shingle embankment, protection to Portland Harbour on the west and south-west, and the object of the breakwater was to secure, by engineering art, a similar protection to the bay on the south-east side. The Chesil Bank, though now and for long perfectly impregnable to the tremendous rollers of the south-westerly gales, was not always so, and as late as the reign of Henry VIII, great breaches had been temporarily effected by the power of the sea. Still it affords a splendid protection, as does now the mighty double breakwater designed by Rendel, and brought to completion by Coode. The breakwater leaves the sh.o.r.e at the north-eastern extremity of the island, and runs out due east to a distance of 600 yards. "This inner limb alone," wrote an authority in engineering,(65) "is a splendid achievement of human labour and skill. It has been top-finished by a grand superstructure of hewn granite, and ends in a circular head, which has been completed as a fort and mounts eight guns. The foundations of this ma.s.sive bastion have been most carefully planned, with especial reference to the safe pa.s.sage of the largest vessels through the 400 feet gap which the fort flanks on one side. The masonry is continued in a perpendicular line to a point 25 feet below the lowest water-line of spring-tides. A ship of the line, as is well-known, draws at the utmost 24 feet. An extra foot of perpendicular masonry, therefore, having been allowed, the lower ma.s.ses of the fort begin to slant outwards, and continue to do so till they reach the firm clay bottom. This lower portion consists of a well-consolidated ma.s.s of unhewn stone. The outer, and by far the longer limb, of the breakwater begins to bend away to a point very near due north shortly after leaving the gap, the further side of which is also flanked by a circular head.... The whole of this vast outer limb, with the exception of the circular head at its inner extremity and a fort at the other end, consists of nothing more than a stupendous bank of rough unhewn stones of all shapes and sizes, tumbled out of the wagons on the timber staging above. Divers, constantly employed, have effectually prevented the chance of any holes being left in the rising ma.s.s, and have been able to indicate the precise spot over which a given number of loads were required to be "tipped." The security of the bank is further guaranteed by its enormous width at the base; and although the waves have already rounded many a giant block below the water-line and made it look as if its present place had been its abode ever since the Creation, yet this polishing and grinding is the extent of the effect which they will be able to produce upon a work probably destined to hold its own as long as Portland itself."
The rapidity with which the breakwater was constructed reflected great credit on Mr. Coode. The actual routine of the construction followed, when the line for the structure had been sounded and carefully marked out, was to commence piling for the railway that was to carry the long trains of wagons filled with the stone; and when a short piece of this was completed, to go on "tipping in" the rubble and rough stone till they made their appearance above water at last; then the piling was carried forward a few yards more, and the process repeated, and so on by successive stages to the completion of the work. All appears very simple on paper until we learn that it had to be accomplished through eleven fathoms of rough tumbling waves. One night"s rough weather often swept away the timber-work that cost many thousands of pounds, and many months of labour to construct and fix in its position in the sea. The piling that had to resist the action of a deep and heavy sea, and to carry also, at a height of 90 feet, a railway for the heaviest traffic, required to be something more than a common framework of timber. Every log used had to be first of all saturated to its very centre with creosote, and this was done in a most ingenious manner. A great boiler, 100 feet long and 7 feet in diameter, was filled with the largest and finest logs procurable; the mouth being closed with a solid air-tight cover, the air was pumped out, not only from the tube, but from the very pores of the wood itself. When the vacuum was as complete as possible, the creosote was admitted from tanks at the bottom and forced into the timber by hydraulic power of about 300 lbs. to the square inch. In this the logs remained for two or three days, by which time the creosote was forced into the fibre of the wood. Several of the logs thus prepared were bolted and bound together, till one huge spar 90 feet long, and eight or nine tons in weight, was formed. Then an iron "Mitch.e.l.l" screw-as used in the lighthouses built on sands, already described-was affixed at the lower end, and the whole sunk till it rested on the bottom, when it was worked round by a capstan till it was firmly screwed into the clay. Thus secured, they were tolerably safe, though single heavy waves would uproot piles and moorings together, to obviate which two or three piles were generally set at the same time, and well bound together by powerful cross timbers.
The stone quarried for the breakwater from the very top of Portland Island was largely excavated and brought to the spot by convict labour. The stone itself used was unfit for architectural purposes, but quite suitable for the breakwater. The convict prison, also on the top of the island, was virtually the barracks for 900 labourers, who were more profitably employed than in walking a treadmill or picking oak.u.m. The quarries were some 400 or 500 feet above the level of the breakwater, and the stone was conveyed to it by three inclines of broad double gauge rails. The trains of trucks or wagons were worked up and down with a wire rope over a drum, the weight of the loaded descending wagons winding the empty ones up again to the quarries. A powerful locomotive pushed the loaded trains to the end of the work, where the stone was tipped into the sea, as much as 3,000 tons a day having been sunk at Portland. The total amount so committed to the deep was about 5,360,000 tons, and the area protected by the breakwater would accommodate sixty of the very largest men-of-war, and almost any number of smaller vessels.
"During the progress of the works," wrote Mr. Moule, "the engineer has from time to time inst.i.tuted some highly interesting investigations into the structure of the Chesil Bank.... During a single night"s gale, between three and four _millions of tons_ weight of pebbles have been found to be swept away into the gulfs of the Atlantic, being gradually thrown back again in the three or four following days. The size of the pebbles had long been observed to vary greatly at the two opposite ends of the beach.
At the western, or Abbotsbury end, they are exceedingly small, more resembling gravel than shingle. At the Portland end it is not uncommon to meet with them several inches in diameter, and several pounds in weight.
This phenomenon has been explained by the very probable a.s.sumption that the pebbles are driven eastward by the wind-waves, and not moved by the slow and (for purposes like this) powerless tidal current. The larger pebbles, presenting a broad surface to the waves, are easily rolled forward, while the smaller ones are pa.s.sed by, offering a less surface, and becoming more easily imbedded in the sand." It is said that a practised smuggler on that coast could tell his whereabouts on the bank in the darkest night or thickest fog, by feeling the size of the pebbles on which he stood. And smugglers and "wreckers" were once very numerous among the Portlanders. In these better days their courage and great personal strength has saved many a life and ship endangered off the bank.
An old and popular song says that-
"Britannia needs no bulwarks, No towers along the steep,"
but recent legislators have evidently not been so thoroughly satisfied of the fact, or they would not have authorised the construction of the great fortifications at Portland, which make it almost the Gibraltar of the Channel. The splendid breakwater there did not need protection. All the battering it is ever likely to get could not injure it seriously, and whatever ruins Macaulay"s New Zealander may stand upon, they are not likely to be those of a great breakwater, each year of the existence of which renders it generally more compact. But it was for good reasons that the extensive works of Portland were undertaken. "We," said the _Times_, "of all people in the world, who so toiled and suffered, lavishing blood and treasure under the walls of Sebastopol, should be the last to underrate the importance of a good fortification as a check to an invading army." The reader will hardly require any defence of such policy, for naval a.r.s.enals contain the very germ of our power, as the iron safe of the prudent man contains his valuables.
The Bill of Portland greatly resembles the situation of Gibraltar. There are the same bold, steep, rocky headlands; the breakwater stands in place of the Mole, and Chesil Bank connects it with the mainland, as the neutral ground does our great Mediterranean citadel with Spanish soil. "Its height, its isolation, and the harbour it commands, all pointed it out as a place for an impregnable-we had almost said an inaccessible-fortress. To the late Prince Consort is due the credit of having seen its vast importance in this respect, as it was also owing to his enlightened judgment that the breakwater was begun at last, and he himself laid the foundation-stone. Portland is rising, as we have said, into a first-cla.s.s fortress, of which the Verne is the great key or citadel." So spoke the _Times_, in 1863; and now Portland is the best fortified port and naval station in the kingdom.
The Verne is a height which, like La Roche at Cherbourg, dominates over all around it for miles, especially on the side which overlooks the breakwater and the sea. On the north side it is protected by nearly perpendicular cliffs; elsewhere it is fully protected by art. One of its greatest defences is the dry ditch which completely encircles the whole work, except on the north side just mentioned, where it is both unnecessary and impossible. This ditch is one of the greatest ever undertaken in ancient or modern days. Its depth is 80 feet, and its width 100, and in some places 200 feet; its length is nearly a mile, and its floor is 368 feet up the hill-side. Nearly two million tons of stone had to be blasted to form it; and it would never have been excavated on the colossal scale indicated, but that all the said stone was utilised in building the breakwater. With this tremendous artificial ravine to cross, with fortifications and bastions fully prepared with heavy Armstrong ordnance towering above, what enemy is ever likely to attack the citadel of the Verne? Our leading journal spoke of it as more compact than Cherbourg, Cronstadt, or Sebastopol, while it is more than three times their elevation above the sea.
Jutting out from the main fortress are two bastionettes, one of which has eight faces, mounting guns on each so as to sweep with a murderous fire two-thirds of the whole length of the fosse or ditch. The other is nearly as formidable, and both are pierced with loop-holes in all directions for the fire of riflemen. The great barracks in the enclosure of the Verne can, at a pinch, accommodate 10,000 men, the peace garrison being about a third of that number. The arrangements for water supply are perfect, great reserve tanks having been cut from the solid rock, and covered with shot-proof roofs. These are kept full, and, protected from air and light; the water is always sweet. Portland bristles with batteries; but the Verne commands everything in range of cannon, inside or outside the breakwater, including all parts of the island, and can cross fire with other important forts. It is probably the strongest fortified harbour in the world.
[Ill.u.s.tration: HOLYHEAD BREAKWATER.]
Other and important breakwaters, like that of Holyhead, which cost a couple of million sterling, and which is generally cited as an example of much money thrown into the sea; Alderney, which has swallowed up close on three-fourths of the above sum; and Dover, which has a fine _vertical_ sea-wall, might be mentioned. Enough has been said to show the general importance of the subject to a maritime people, and that, on the whole, England has been fully alive to the fact. Indeed, counting large and small breakwaters and sea-walls, more has been expended in this country for these works than in any two or three foreign countries possessing sea-boards.
CHAPTER XIV.
THE GREATEST STORM IN ENGLISH HISTORY.
The Dangers of the Seas-England"s Interest in the Matter-The Shipping and Docks of London and Liverpool-The Goodwin Sands and their History-The "Hovellers"-The Great Gale of 1703-Defoe"s Graphic Account-Thirteen Vessels of the Royal Navy Lost-Accounts of Eye-witnesses-The Storm Universal over England-Great Damage and Loss of Life at Bristol-Plymouth-Portsmouth-Vessels Driven to Holland-At the Spurn Light-Inhumanity of Deal Townsmen-A worthy Mayor Saves 200 Lives-The Damage in the Thames-Vessels Drifting in all Directions-800 Boats Lost-Loss of Life on the River-On Sh.o.r.e-Remarkable Escapes and Casualties-London in a Condition of Wreck-Great Damage to Churches-A Bishop and his Lady Killed-A Remarkable Water-Spout-Total Losses Fearful.
"The dangers of the seas" are little enough to some countries, but to England they mean much indeed. Think of the maritime interests of the port of London, the docks of which cover considerably over 300 acres of water-s.p.a.ce, and to which 7,000 or more vessels enter annually. Over 100 vessels, exclusive of small craft, enter the port daily; its exports form nearly one-fourth of the total exports of the United Kingdom. Liverpool in some maritime interests excels it. This, the second largest city in Great Britain, had, as late as 1697, a population of only 5,000; 80 small vessels then belonged to the port. In this year of grace, Liverpool, with her virtual suburbs, Birkenhead and West Derby, has a population considerably over 700,000. In 1872, Liverpool exported, in British and Irish productions, a total value of 100,066,410, which meant little short of forty per cent. of the total exports, of the same kind, from the United Kingdom, while its imports of many staples exceeded those of London.
Liverpool has nearly sixty docks and basins, extending along the Mersey for five miles. She possesses nineteen miles of quays, nearly the whole of which have been built since 1812, and warehouses on a scale of magnificence unknown elsewhere.
But such a commerce means much more. Hundreds of thousands of hardy men risk their lives that we may have bread and b.u.t.ter, sugar with our tea, and all the necessaries and luxuries of modern civilised life. England has not forgotten them, and for their use has built the lighthouse, the breakwater, and the harbour of refuge. But there are sources of danger which nearly defy human power. Take, among all dangerous shoals and sands, the Goodwin Sands as a prominent example; they are replete with danger to all sailing vessels at least, resorting to the Thames or to the North Sea, while even steamships have been lost on their treacherous banks.