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LIGHT-HOUSE ENGINEERING. Abstract of Paper by Mr..J. A. Purves, D. Se., F.R.S.E., read before the Institution of Engineers and Shipbuilders in Scotland, on October 16th, 1899. The history of lighthouses dates from the earliest days when such shipping as then existed was warned and guided by means of open fires kindled upon projecting headlands or other elevated sites. The next advance seems to have been made by the Libyans and Cushites, dwellers in lower Egypt, who made use of watch-towers during the day, which were used as beacons at night, open fires being lit upon their summits, These, however, are largely conjectural, and the first actual lighthouse, of which a written account exists, appears to be that of Sigeum, which was erected by Lesches, author of the ‘‘Little liad,”’ sometime about the year 744 B. C. Following upon this comes the world-famed Pharos of Alexandria, one of the seven wonders of the world. ‘This lighthouse, which has given the name of Pharology to the science of lighthouse engineering, was, according to Pliny, built by Sostratus, by command of Ptolemy Philadelphus, about the year 284 B. C. According to other writers, the building was square in cross section, consisting of many storeys, which diminished in size toward the top. Its height is given as equal to 512 English feet, and the cost has been calculated as equivalent to £195,000 in modern money, and we are told by Josephus that the fires lit upon the summit were visible for about 29 geographical miles. With the rise of the Roman Empire, coast illumination progressed rapidly, and lights are mentioned as existing at Ravenna, Puzzoli, Ostia, and elsewhere. The lighthouse at Corunna, in Spain, is perhaps the oldest existing tower now used as such, dating from the days of Trojan, A. D. 98-117. At Dover Castle there are remains of a Roman tower, built about 53 A. D., which is supposed to have been used as a lighthouse; there is also reason to believe that the Romans established a light upon Flamborough Head, and another on the coast of Flint- shire. ‘The first actual tower which was built with the express and sole object of a lighthouse seems to be the Tower of Cor- duan, in the Bay of Biscay, which may be taken as the start- - ing point of the modern lighthouse engineering. The Light- house Tower of Corduan guarding the mouth of the river Gironde, was designed and executed by Louis de Foix, in the reign of Henry IV. of France, and was completed in the year 1611, having taken 26 yearsto build. In many ways this tower may still be looked upon as the finest lighthouse in the world, and its form remains practically unaltered, even after a lapse of 300 years. Next in importance and order of date, is the Eddystone. This lighthouse, which has probably attracted more public interest than any other, marks the Eddystone rocks, lying some fourteen miles off Plymouth. The first actual attempt _to-erect a permanent building was made in 1696 by Henry Winstanley, who undertook to establish a lighthouse upon the rocks. The work was commenced in that year, and com- pleted in four years. It consisted of a cylindrical lower por- tion of masonry 16 ft. in diameter, above which was the gal- lery andlantern. The total height of the building was 80 ft., and the light was first exhibited in 1698. A year later, it was deemed advisable to increase the diameter of the build- ing, and to increase the total height to 1z0ft. This was completed in 1700. In November, 1703, the entire structure was washed away, and the unfortunate Winstanley, who then happened to be in the tower, perished amidst the wreck. In 1706 Mr. Rudyerd undertook the erection of a new tower. This consisted in its lower portion of timber work, bolted together and to the rock, and above this were placed stone courses surmounted in turn by a second course of wood work. Despite the composite nature of this structure, it weathered the storm for forty-six years, and its final destruction was caused ‘not by water, but by fire. Following upon Rudyerd’s tower comes the ever memorable Tower of Smeaton. This triumph of engineering skill has served as the model from his day till ours of all rock towers. It was begun in 1756, and completed in 1759. The building was entirely of stone, - the individual blocks of which averaged one ton in weight. These stones were all dovetailed together from Smeaton’s design, which was the first in which dovetailed joints were employed. The total cost of the work amounted to £40,000 the cost per cubic foot of structure being £2 19s. 114d. In 1877 it became apparent to the Trinity House that, al- though the tower was still in good preservation, the rock upon which it was built was showing signs of being under- minded by the action of the sea, and it, therefore, determined to erect a new lighthouse some 120 feet S.S.E. from the site — of the old one. The building was commenced in 1878, and THE MARINE RECORD. completed in 1882. The curvilinear outline of the old Ed- dystone and of other towers had the effect of raising the cen- ter of pressure of each impinging wave, and this led Sir James Douglass to design his towers with a cylindrical base carried to 2% ft. above high water; above this, and set some little distance in, is the curvilinear structure, which is really a concave elliptical frustum. The base is 44 ft. in diameter and 22 ft. high, while the total height of the tower is 173 ft. The tower is solid for 25 ft. 6 in. above high water, while the walls, which are 8 ft. 6in. at the bottom, taper to 2 ft. 3 in. at the thinnest part of the service room. All the stones, which are of Cornish and Scottish granite, are dovetailed both horizontally and vertically. The lower courses resting upon the rock are sunk to a depth of one foot, and bolted to the rock by Muntz metal bolts. ‘The lantern surmounting the tower is of the helical type, while the optical apparatus which it contains is of the biform group flashing type, giving two groups of two flashes in quick succession. The maxi- mum candle power of this apparatus is about 79,000, the luminary being a six wick burner. This lighthouse is further provided with fog bells, which are actuated by means of the same mechanism which rotates the apparatus. The total cost of this building was £59,255, equivalent to 18s. 2d. per cubic foot ot building. The work was executed under the personal superintendence of Mr. W. T. Douglass, son of the late Sir James Douglass. The Bell Rock lighthouse, which marks the dangerous reef of rocks known as the Bell or Inchcape Rock, lies some twelve miles off the coast of Forfarshire, and fully exposed to the waves of the North Sea. The lighthouse was begun in 1800, and its site is 16 ft. below high-water mark, or just above the level of low-water spring tides. The tower was designed and carried out by Mr. Robert Stevenson, who, ina measure, took the Eddystone of Smeaton for his model. He, however, increased the thickness of the walls as com: pared with the Eddystone, and carried the solid portion to a greater. height. Next in order of date is the Skerryvore Lighthouse, off the Argyllshire coast. This tower, the cone of which is hyperbolic, was designed by Mr. Allen Stevenson. The work was begun in 1838 and was not completed till 1843. The tower is entirely of granite. It contains 58,580 cubic feet of masonry, and its total cost amounted to £72,200 IIs. 6d., equal to £1 4s. 73d. per cubic foot of structure. The apparatus used in this tower is an eight-sided first-order, with a power of beam eqnal to 44,000 candles. The light gives one flash every half minute. The tower of Les Baleines, built upon the I’le de Re on the west coast of France, was completed in 1854. The La Coubre Lighthouse is also upon the west cost of France. The tower is cylindrical and of masonry; its height is 172 ft. The building was completed in 1860, and in 1895 a new electric apparatus was installed to replace the old oij one. The Wolf Rock Lighthouse, off Lizard Point, was design- ed by Mr. James Walker and was begun in 1862. Its height is 116% ft., its diameter at the base 41 ft. 8 in., diminishing to 17 ft. at the top. The solid portion is carried up to 39 ft. 6 ins. The form of the tower is an elliptic frustum of a cone. The Dhu Heartach Lighthouse is 14 miles from the Island of Mull. The tower is parabolic in outline, and is entirely constructed of granite, its height being 145 ft. Roches Douver, on the north coast of France, is a hand- some iron structure, 182 ft. in height, built in 1879. The apparatus employed has a candle power of 28,800, Cape San Thome, this iron lighthouse was constructed by Messrs. Barbier and Benard, of Paris, and erected for the Brazilian Lighthouse Service in 1882. Its total height is 148 ft. The Bishop Rock Lighthouse, situated upon the western- most part of the Scilly Islands, is exposed to the full stretch of the 3,000 odd miles of the Atlantic. Thesiteis of historic interest, being the scene of the disaster which fell upon Sir Cloudesley Shovel’s squadron in 1703. In 1847 the Trinity House began the erection of an iron open work structure upon the Bishop Rocks. The most recent continental lighthouse’ towers is Pen- march. Although a land and not a rock station, it is well deserving of attention. The tower, built entirely of granite, was only completed in October, 1897. It guards the promi- nent headland of Cape Finisterre, and it owes its being largely to the generous bequest of the Marquis de Blocque- ville, who left the sum of £12,000 for the erection of a light- house to adequately protect the coast. The height of the DECEMBER 14, 1899. tower above the ground is 207 feet, while in addition to the tower are the dwelling, dynamo, siren, and engine houses. The luminary in this lighthouse is an electric arc, and the apparatus is of the twin type, where both are mounted side by side upon a revolving table, instead of being superposed, as in the case of the new Eddystone and Bishop Rock Light- houses. The maximum candle-power of this apparatus is 30,000,000. The total cost of the tower and buildings amounted to £16,000, while the apparatus with all its elec- trical generating plant cost £5,000, and the siren installa- tion £1,200—a total, including carriages and sundries, of 423,200. In the early days of lighthouse illumination, when coasts were but scantily supplied with lighthouse stations, which were situated at great distances apart, the old fixed lights, were all that could be desired, and served their purpose ‘well. As the number of lights increased it was found neces- sary to furnish some distinction between one light and an- other, so as to guide the mariner upon his way in safety, and this end was ina large measure accomplished by the in- troduction of the revolving and occulting lights. This diffi- culty has, however, been met most successfully by Dr. Hop- kinson’s group-flashing system now so universally adopted in newer lights. The group-flashing system, good in so many ways, has one serious disadvantage, which is that a well-marked and distinctive characteristic is obtained at the expense of power of beam. Thisis necessarily so, as the power of the emer- gent beam is a direct function of the number of beams em- ployed. The beams are further necessarily weakened in most cases by having a larger proportion of reflecting prisms than in the single flash panel. Since 1892 no light of over 100,000 candle-power had been installed in Scotland, while in France no fewer than ten lights of a total candle-power of 102,810,000 have either been altered to their present power or newly installed. In the second class of lights, those between 40,000 and 100,000, the number of lights in Scotland and France is equal, and in ‘this case the total candle-power of the Scottish lights is su- perior to that of the French, the Scottish being 206,000 and the French only 173,000. In class 3, where the lights are between 22,000. and 40,690, the French have either newly in- stalled or altered 31 lights to our 3 since 1892, their total candle-power amounting to 156,0co as against our 90,000. In class 4, which includes all lights between 10,000 and 22,000, the French have either freshly installed or altered 7 lights to our 2, the respective candle-powers being in France 97,- ooo and in Scotland 34,000. In class 5, where the lights are between 5,000 and 10,000, Scotland has added no new light, “while France has either newly erected, or brought up to this standard of efficiency 6. In the sixth class, between 1,000 and 5,000 candle-power, France’s totalis 10 lights to 3 for Scotland. In class 7, France has to be credited with 12 lights, all installed or altered since 1894, while Scotland has neither installed nor altered any lights of this size since 1892. In class 8, where the lights are between 100 and 500, there are 12 lights in the French lists as against 5 in the Scottish, while in the last and smallest class France can claim 50 lights as against Scotland’s 20. The French lighthouse service of the present day is able to maintain both a constant yearly expenditure on mainten- ance and new works with an’ ever-increasing number of power of lights. It was in 1890 that the late M. Bourdelles, the distinguished head of the French Lighthouse Service. devised the system of lighting lights known as the Feux- Eclairs, and from that day onward the French lighthouse system has advanced by ieaps and bounds. This system of lighting is universal, with the exception of our own land. The advantages are so obvious as scarcely to require pointing out, but the fact remains, nevertheless, that it is not adopted in our country. _—_— Oe oO oe A CANADIAN SHIPBUILDING PLANT. H. M. Whitney, of Boston, and Alfred J. Moxham, the general manager of the projected iron works at Sydney, C. B., are said to be making arrangements for locating a steel shipbuilding plant at North Sydney. Negotiations with the General Mining Association, looking to the purchase of asso- ciation mines at North Sydney are reported to be in progress. The price mentioned is $1,500,000. rr rm ee ANOTHER new book of the sea: ‘‘Pikeand Cutlass;’? Hero Tales of Our Navy, written and illustrated by Geo. Gibbs, 300 pages. phia, Pa. Price $1.50. S Published by the J. B. Lippincott Co., Philadél-