CHAMBERS'S INFORMATION FOR THE PEOPLE. 



In addition to the instruments already named 

 namely, the compass, log, sextant, and chrono- 

 meter every ship carries a barometer of the most 

 delicate construction. In parts of the world where 

 storms come on suddenly, and almost without 

 visible warning, this instrument is invaluable in 

 giving timely notice of their approach, and so 

 allowing sails to be reefed and other preparations 

 to be made, for which without notice there would 

 not be time. The log-book of a ship has already 

 been mentioned. In it are entered all occurrences 

 of importance during the journey, and it is pre- 

 served with great care for exhibition when required 

 at the end of the voyage. Charts, which differ in 

 many respects from ordinary maps, and which are 

 of various kinds (as plane, Mercator's, &c.), arc as 

 indispensable to the captain as his compass, and 

 on them he daily marks the ship's position, in 

 accordance with the reckoning and observation. 



LIGHTHOUSES, BEACONS, AND BUOYS.* 



These means of warning the mariner off sunken 

 rocks and dangerous sand-banks or coasts arc 

 among the most indispensable adjuncts of mari- 

 time conveyance. More or less obscure notices 

 exist of the lighthouses or beacons of Pharos and 

 Rhodes, many years B.C. ; but the oldest modern 

 lighthouse of which we have any detailed infor- 

 mation is the Tour de Cordouan, a tower 145 feet 

 high, situated on a low rock three miles from land 

 at the mouth of the Garonne. It was founded in 

 1584, and finished in 1610, and still remains one of 

 the finest of its class, although, of course, all its light- 

 ing arrangements are changed from the primitive 

 ones at first used, to the elaborate arrangements 

 which alone are now considered efficient. It was 

 originally lighted by blazing fagots of wood in an 

 open chauffer and many of the older beacons 

 (among others one that existed on the Isle of 

 May till 1816) were simply open coal-fires. 

 These possessed the negative qualifications that 

 they were liable to be almost entirely obscured at 

 intervals by their own smoke, and that in strong 

 gales they would only light on the leeward side, 

 and so were entirely invisible where alone they 

 could be of use. They thus, by the irregularity of 

 their light, were as often a source of danger as of 

 safety to the sailors who relied on their appear- 

 ance. 



The most celebrated lighthouses of our own 

 day are the Eddystone, the Bell-rock, and the 

 Skerryvore. The first is situated on a low and 

 very dangerous reef of rocks, south-south-west 

 from the middle of Plymouth Sound, and about 14 

 miles from Plymouth. As early as 1696, a gentle- 

 man named Winstanlcy obtained the necessary 

 powers to build a lighthouse there. The build- 

 ing was made of wood, and was finished in 1700. 

 So certain was Winstanley of the stability of his 

 structure, that he declared it to be his wish to be in 

 it ' during the greatest storm that ever blew under 

 the face of heaven.' The tragical way in which his 

 wish was gratified when, in 1703, the whole fabric 

 was swept away in a night, with workmen, light- 

 house keepers, and Winstanley himself, is well 

 known. The necessity of some beacon on the 



* For much of the information in this section, we are indebted 



to a capital little book by Mr David Stevenson, F.R.S.E. entitled 



Lighthouses, 



462 



Eddystone was so urgently felt, however, that in 

 1709 another wooden lighthouse was built by a 

 Mr Rudyerd. This was burned down in 1755 ; 

 and then arose the building which for more than 

 1 20 years braved every storm, and stood then as 

 perfect as the day on which it was finished. This 

 third edifice was the work of Mr Smeaton, the 

 celebrated engineer. He fixed on stone as the 

 material for his erection, and chose for its shape 

 an outline resembling that of an oak tree, a grace- 

 ful -[curve which combines intrinsic beauty with 

 the highest degree of strength. The work was 

 begun on 2d April 1757, and finished on 4th 

 August 1759. The slope of the rock was cut into 

 steps, into which were dovetailed, and united by 

 strong cement, Portland stone and granite blocks. 

 The tower was 68 feet high. The rock which 

 served as its base having unfortunately been 

 undermined by the action of the water, a new 

 lighthouse was begun in July 1878 on the south 

 reef, 120 yards from the old one. Like its pre- 

 decessor, it is ingeniously dovetailed throughout. 

 Its dioptric apparatus,* at an elevation of 120 

 feet, gives a light equal to 230,000 candles, visible 

 to a distance of 17 miles in clear weather. It was 

 completed in 1882, and the old one was removed. 

 The Bell or Inch-cape Rock is a sunken reef 

 on the east coast of Scotland, between the mouths 

 of the iirths of Forth and Tay. Tradition says 

 that the abbots of Aberbrothock succeeded in 

 fixing on it a bell, which was rung by the swell of 

 the sea, so as to warn the mariner of his situation ; 

 but that this benevolent erection was destroyed by 

 a Dutch pirate, who, to complete the story, was 

 himself afterwards lost on the rock with his vessel 

 and crew. Be this as it may, it was only in 1 800 

 that Mr Robert Stevenson, engineer to the 

 Northern Lighthouse Board, prepared his design 

 for a substantial lighthouse after the model of the 

 Eddystone. He had very special difficulties to 

 contend against. While the Eddystone rock was 

 only submerged at high-water, the Bell-rock was 

 barely uncovered at low-water. Only with a low 

 spring-tide and a smooth sea could a landing be 

 made at all, so that during the first two years, the 

 aggregate time during which the rock could be 

 worked at did not exceed 400 hours, in snatches 

 of an hour or two at a tide. Operations were 

 commenced in 1807; and the light was first exhib- 

 ited in February 1811, and many were the adven- 

 tures and narrow escapes during that time of 

 those employed in its construction. 



When footing cannot be had to build a tower, 

 floating lights are used. The lightship is a vessel 

 of about 150 tons burden. The lantern surrounds 

 the mast, on which it is raised when hoisted. The 

 vessel is manned by a crew of eleven men, so 

 as to work her in case of her breaking adrift. 



The subject of lighthouse illumination is one 

 which has engaged the careful attention of modern 

 scientific men. It depends upon mathematical 

 and optical principles which cannot be entered 

 upon here, but their results may be briefly 

 summarised. The object to be attained is to 

 collect all the light from the lamp, preventing its 

 diffusion upward and downward, and to send it 

 out to sea in a concentrated beam in the direction 

 which will be most useful to the sailor. Two 



* The only light that was exhibited from the Eddystone in 

 Smeaton's time came from a frame supporting 24 candles. 



