MARITIME CONVEYANCE. 



methods are in use to attain this object. The 

 older is called the catoptric, or reflecting system. 

 By it each lamp is placed in the focus of a para- 

 bolic reflector, which, by virtue of its curve, 

 reflects all the rays parallel to each other out sea- 

 ward. The second method is called the dioptric, 

 or refracting system, and originated with the late 

 Augustine Fresnel. Instead of a number of 

 burners in the foci of reflectors, he used one large 

 central flame, surrounded by a number of plano- 

 convex lenses. The light, in passing through 

 these lenses, is refracted into a beam of parallel 

 rays similar to the reflected beam in the catoptric 

 system. Very elaborate arrangements of prisms 

 are used to catch all the upward and most of the 

 downward rays, and throw them out to sea along 

 with the rays passing through the principal lens. 



If all lights had the same appearance, the sailor 

 would often have difficulty in distinguishing one 

 from another ; each one, therefore, must have its 

 own distinctive character. The following are the 

 principal classes of lights : The fixed, which 

 throws a steady beam in all directions ; the 

 revolving, in which, by the revolution of lenses 

 or reflectors, the light is made gradually to 

 decrease, and then again gradually to increase in 

 intensity at certain intervals ; the flashing, in 

 which, by a slightly different arrangement of 

 apparatus, the changes are sudden and rapid, 

 instead of gradual ; and the intermittent, in which 

 the light is totally obscured by shades for half a 

 minute at intervals. By the use of ruby-coloured 

 glass chimneys to the lamps, each of these classes 

 may be made to throw a red instead of a white 

 light. Blue and green lights are not sufficiently 

 visible at great distances to be of use in light- 

 houses. 



Lighthouses near towns are sometimes illumi- 

 nated with gas, but in general argand lamps are 

 used, fed with colza oil. Of late years, many 

 experiments have been made, under the auspices 

 of the Trinity House, with magneto-electric lights, 

 and in 1880 these were regularly used in some 

 half-dozen English lighthouses ; but practical dif- 

 ficulties still prevent their extensive use. 



The management of our lights is in the hands 

 of three public boards namely, the Trinity House 

 for England, the Commissioners of Northern 

 Lighthouses for Scotland, and the Ballast Board 

 of Dublin for Ireland. The two latter arc, to a 

 certain extent, under the control of the Trinity 

 House, and the whole of the three, in many 

 respects, come under the jurisdiction of the Board 

 of Trade. 



Beacons are generally placed on sand-banks, 

 rocks, or shoals, and are either floating or sta- 

 tionary. When floating, they are called buoys, 

 and are used both to point out the position of the 

 hidden danger, or to mark out the course which 

 vessels ought to follow, and as mooring-buoys, for 

 ships to fasten themselves to in rivers or harbours. 

 Stationary beacons may be considered to be 

 lighthouses without lights. Their great defect is, 

 therefore, that they are not visible on dark nights, 

 just when they are most required. Mr Thomas 

 Stevenson has introduced with success a mode of 

 illuminating beacons near the shore, when it is of 

 the utmost consequence that their exact position 

 should be known, but when it is not expedient or 

 possible to erect a lighthouse. This is managed 

 by what he terms an apparent light, produced by 



placing a reflecting apparatus on the top of the 

 beacon, to which is transmitted from a lighthouse 

 on shore a beam of light, which is dispersed by 

 the apparatus in the required direction; thus 

 producing all the useful results of a light-house. 



SHIPWRECKS AND LIFE-BOATS. 



Notwithstanding every precaution of lighthouse 

 and beacon, shipwrecks are continually occurring 

 at different parts of our coasts, and to save the 

 lives of the seamen in such cases without 

 reference to the fate of the vessel has ever been 

 a subject of earnest consideration. During last 

 century several life-boats were invented, the best 

 known being Mr Greathead's, which gained a 

 premium offered by the inhabitants of South 

 Shields, as well as the gold medal of the Society 

 of Arts, and a parliamentary grant of ^1200. 

 Although various other life-boats were invented 

 from time to time, Greathead's remained the 

 general favourite until about the year 1851, and 

 many of his construction are still to be seen on 

 different points of the coast. They failed, how- 

 ever, occasionally ; and several sad mishaps befell 

 the crews of life-boats, especially in the case of 

 one at South Shields, in which twenty pilots 

 perished. Upon this the Duke of Northumber- 

 land offered a prize for an improved construction, 

 and numerous designs were submitted, a hundred 

 of the best of which were exhibited in 1851. Mr 

 James Beechipg of Yarmouth obtained the award; 

 but his boat was not considered entirely satis- 

 factory, and Mr R. Peake, of Her Majesty's Dock- 

 yard at Woolwich, was intrusted with the task of 

 producing a life-boat which should combine the 

 best qualities of the different inventions. His 

 efforts were very successful, and the National 

 Life-boat Institution adopted his model as the 

 standard for the boats they should thereafter 

 establish on the coasts. The boat thus adopted 

 is from 30 to 40 feet long, its breadth being about 

 one-quarter of its length. It is generally rowed by 

 ten men, sitting in a double row. It is made with 

 a great deal of sheer that is, with the line of the 

 gunwale much lower in the centre than at the 

 ends. There is an air-chamber at each end and 

 along each side ; and cork is fitted in the space 

 between the deck and the floor, or lower skin of 

 the boat. The object of the great sheer and of 

 the end air-chambers is that the boat may not be 

 able, if capsized, to float bottom upwards, but may 

 always tend to right itself. This self-righting is 

 one of the most important qualities which a life- 

 boat can possess. Six relieving tubes, each six 

 inches diameter, with valves opening outwards, 

 are fitted, to allow of the boat being emptied (to 

 the surface-level) when filled by a heavy sea : the 

 rest of the water is then pumped out by hand. 



The importance of the life-boat in saving life 

 can scarcely be over-estimated. Hundreds of 

 vessels have their crews rescued through its use 

 every year ; and as the National Life-boat Insti- 

 tution obtains funds, this invention is being 

 gradually extended all round the coast of the 

 United Kingdom, while foreign nations have not 

 been remiss in thus protecting their shores. 



The Royal National Life-boat Institution, after 

 an unrecognised existence for, several years, was 

 formally incorporated in 1824. Its objects are, to 

 provide and maintain in efficient working order 



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