June 2, 1887] 



NATURE 



103 



appeared of a dirty brown colour, very different from what 

 " Bishop's ring " used to be, and I have thought that often it 

 has not been in the upper atmosphere, but at a lower altitude, 

 and most visible when there has been more or less smoke ; so 

 that it seemed not improbable the snioke was the cause of it. 

 Has anyone else noticed such a phenomenon connected with 

 smoke? '* Bishop's ring," as still seen at sunset, is evidently 

 not caused by smoke, but doubtless arises from the same cir- 

 cumstances as made it so conspicuous an object at its first 

 appearance in November 1883, and gradually less so since. 



The whitish wisps occurring in and near the ring about sun- 

 rise and sunset continued visible at intervals, and varying 

 greatly in distinctness, up to the 31st ult. I have not seen 

 them since, but they have been invisible for longer periods 

 before. T. W. Backhouse. 



Sunderland. 



A REVIEW OF LIGHTHOUSE WORK AND 

 ECONOMY IN THE UNITED KINGDOM 

 DURING THE PAST FIFTY YEARS 



I. 



IT may be useful to recapitulate very briefly the various 

 steps of progress in this important branch of engineer- 

 ing and optical enterprise since the beginning of the 

 Queen's reign. And a few words may be added on the 

 statistics and economics of the subject. 



A lighthouse or lightship is naturally to be considered 

 under four heads: (i) tower or hull and its lantern; 



(2) optical apparatus and its mechanical accessories; 



(3) lamps and illuminants ; (4) auxiliary sound signals. 

 In 1837 a high degree of excellence had been attained 



in the first division, at least as regards stone towers and 

 wooden vessels, but in the others stare super antiquas 

 vias was a practice largely submitted to. The number 

 also of established lights was comparatively small, about 

 seventy of all kinds being in England and Wales, less than 

 one-fifth of the present number. France, where there had 

 been from 1 824 to 1 827 an active movement in the direction 

 of coastillumination,possessedin 1836 about 100 lights. In 

 1822, and again in 1834 a Parliamentary Committee had 

 inquired into the character and management of our light- 

 houses, with results to be noticed by and by. 



In 1837 the old working Phari of Greece, Carthage, and 

 Rome, from Alexandria to the Pillars of Hercules, had 

 long since disappeared, leaving only a few vestiges, chiefly 

 on the shores of France, Spain, and Britain. Of modern 

 times the most notable towers were, on the Continent, the 

 imposing Cordouan at the mouth of the Garonne (1610), 

 and the tourist-haunted Lanterna of Genoa, the latter still 

 being the tallest lighthouse structure in the world ; while 

 at home Smeaton's P^ddystone (1759), prototype of British 

 towers, the Bell Rock (i8ii\ the Tuskar (1815), and the 

 Carlingford, on Haulbowline Rock (1823), stood as the 

 most striking examples of such edifices. But in 1838 the 

 great tower of Skerryvore was begun by Alan Stevenson, 

 whose father, Robert, had built the Bell Rock Lighthouse. 

 These accomplished engineers have respectively left a 

 graphic and instructive narrative of their work, which 

 may be fitly clashed with Smeaton's memorable account of 

 the third Eddystone. 



Skerrj'mhore or S\itrryvort{ysgar-mawr=gt&3ii divided 

 cliff, or rocky islet, as in scar, or the hills Skerid Fawr, 

 and Skerid Each) is a nearly submerged reef adjacent to 

 the Island of Tyree, exposed to the full force of the 

 Atlant'C, and surrounded by innumerable rocky points 

 constituting " foul ground " along a line of seven miles. 

 It is thus perhaps the most dangerous of all the skerries 

 in British waters, and differs essentially from the Eddy- 

 stone, which, though formidable in itself, rises from the 

 deep sea, and can be approached more nearly in 

 calm weather. Obviously, then, the 72 feet of elevation 

 of the Eddystone lantern-centre, and even the 93 feet 

 of the Bell Rock, could not afford the necessary range 



to a light intended to give timely notice to mariners of 

 the outlying perils, and a height of 130 feet was adopted 

 for the Skerryvore edifice, which, permitting one of 150 

 feet from focal plane to high water, insured a geographical 

 horizon [of about fourteen nautical miles, or eightefirt 

 miles to a vessel's deck. The mean diameter givetl 

 to this tower was 29 feet, slightly greater than that 

 of Bell Rock, that of Smeaton's Eddystone being 2X 

 feet. The cubic contents are more than four times those 

 of the Eddystone, and more than double those of Bell 

 Rock. There are ten stories below the lantern, for water, 

 fuel, keepers' rooms, and other purposes. The work was 

 completed early in 1844, after extraordinary difficulties and 

 perils, and it is a splendid monument to the energy arid 

 skill of Alan Stevenson. Its cost was ^87,000. 



Yet perhaps some of the towers of the great nation 

 which charges no dues for its lights, but presents thetn a 

 noble offering to the world, are fully as remarkable. 

 Minot's Ledge (1859) on the Massachusetts coast, arid 

 Spectacle Reef, Lake Huron, are example?. The latter 

 structure was begun in 1871, and, though for an inland 

 water, cost ^60,000, the special difficulty having been ice, 

 and the laying, by means of a cofferdam, of the lower 

 courses of masonry on a jagged slope of dolomitic lime- 

 stone 12 feet under water, and eleven miles from lat^d, 

 like the Eddystone. So in the case of Minot's Ledge 

 Tower, the foundations of which were laid on a rock 

 barely visible at extreme low tide, and in the full swell of 

 the ocean, the distinguished engineer General Alexander 

 was able to secure but thirty hours of work in the first 

 year, and 157 in the second. 



The Bishop Lighthouse, on the south- westernmost rock 

 of the Scilly Islands, was completed in 1858 at a cost of 

 ^34,560. After a quarter of a century's service it has been 

 found expedient to increase the height, and to erect a 

 more powerful optical apparatus, which will be ready dur- 

 ing the present year. Other notable towers of the Trinity 

 House are the Smalls (entrance of Bristol Channel), the 

 Hanois (west end of Guernsey), the Wolf, and the new 

 Longships ; all being generally alike in design, and not 

 differing widely in dimensions and cost. The Wolf Tower 

 received its light in January 1870, having been begun in 

 March 1862. It was planned by Mr. Jaines Walker, then 

 Engineer to the Trinity House, but carried out by his suc- 

 cessor, Mr., now Sir James, Douglass, and by his brother, 

 Mr. William Douglass. This lighthouse is situated 

 seventeen miles from Penzance, and twenty-three west- 

 north-west of the Lizard. It has a mean diameter of 

 nearly 30 feet, and a total height of no feet from high 

 water to lantern-centre, being solid for 39 feet from the 

 base, and containing 44,500 cubic feet of granite, weighing 

 3300 tons. Each face-stone is dovetailed vertically and 

 also horizontally — the latter was not done in the Eddy- 

 stone tower — and the courses further secured together by 

 metal bolts. Roman cement was used for the work below 

 water, and Portland cement for that above, the whole 

 mixed with a peculiar granitic sand from a Cornish tin- 

 mine. Very great difficulty, as with all these exposed 

 towers, was experienced in the erection of the Wolf and 

 the new Longships, owing to the terrific seas that assaulted 

 the rocks. The Longships, so conspicuous an object from 

 the Land's End, and so well known from Mr. Brett's 

 luminous pictures, with an original elevation of 79 

 feet above high water, was so drowned by the waves 

 that the character of the light could hardly be discerned, 

 and a granite column of no feet was adopted. 



In Scotland the sea-tower of Dubh Artach, or, less cor- 

 rectly, Dhu Hcartach (1872), and in the Isle of Man that 

 on the Chicken Rock (1875), may be named and the Hst 

 of the chiefstructuresof this type maybe summed up in the 

 Eddystone of Sir James Douglass, from which a light was 

 first shown in 1882. The rapid disintegration of that part 

 of the reef on which Smeaton's tower stood made it ab- 

 solutely clear in 1877 that a new tower must be built if a 



