Chapter 9 of 21 · 3858 words · ~19 min read

Part 9

+----------------+-- | | | | | Name. | | | | | | +----------------+ | | |Casquets | | | | |Eddystone | | |Bishop Rock | | |Spurn Point | |Lundy Island | | |Pendeen | | |Roker Pier | | |Bell Rock | | | | | | |Kinnaird's Head | | | |Tarbet Ness | | |Sule Skerry | | |Pladda | | | |Tory Island | | | | |Fastnet | | | | |Kinsale | | | | |Howth Bailey | | | | | | | |Chassiron | | | | |Cap d'Antifer | | | | |Île de Batz | | |Ar'men |Villefranche |Île Vierge |Kennery Island | | | |Cape Race | | |Pachena Point |Cape Hermes | | |Hood Point | | | |Cape Naturaliste| | | |Point Cloates | | | |Pecks Ledge | | |Fire Island |Gray's Harbor | | | +----------------+ -----------------+--------------+-------+--------+------------+---------+-------------+-------------+------------------+----------+-------+----------+-------------------------------------------------------------+ | | | | Candle- | | Ratio of | | | | | | | | | | | Power in | | Angular | | | Service | Height| | | | Locality. | Character- |Period.|Duration| Standard | Focal | Breadth of | Illuminant. | Burner. | Candle- | above | Year | Remarks. | | istic. | | of | Candles |Distance | Panel to | | | power | High | Estab- | | | | |Flashes.| (Service |of Lens.|Whole Circle.| | |of Burner.| Water.| lished.* | | | | | | Intensity).| | | | | | | | | -------------------+--------------+-------+--------+------------+---------+-------------+-------------+------------------+----------+-------+----------+-------------------------------------------------------------+ | | Secs. | Secs. | | mm. | | | | | Feet. | | | | Channel Islands | 3 flash | 30 | 1.5 | 185,000 | 920 | 1 : 9 | Incandescent| "Matthews" 3-50 | 3300 | 120 | 1877 |Dioptric holophote, 126½° vertical angle; 3 sides of 3 | | | | | | | | petroleum | mm. dia. mantles | | | | panels in each. | | | | | | | | vapour | | | | | | | South Devon | 2 flash | 30 | 1.5 | 292,000 | 920 | 1 : 12 | do. | do. | 3300 | 133 | 1882 |Biform apparatus, lens elements only, 92° vertical angle; | | | | | | | | | | | | | 6 sides of 2 panels each. | | Scilly Isles | 2 flash | 60 | 4.0 | 622,000 | 1330 | 1 : 10 | do. | do. | 3300 | 134 | 1886 |Biform apparatus, lens elements only, 80° vertical angle; | | | | | | | | | | | | | 5 sides of 2 panels each. | Yorkshire | Single flash | 20 | 1.5 | 519,000 | 1330 | 1 : 6 | do. | do. | 3300 | 120 | 1895 |Lens elements only, 80° vertical angle. | | Bristol Channel | 2 flash | 20 | .33 | 374,000 | 920 | Nearly 1 : 4| do. | do. | 3300 | 165 | 1897 |Mercury rotation, 4-panel bivalve. | | | | | | | | | | | | | [St. Mary's Isle, Northumberland (1898), is similar.] | | Cornwall | 4 flash | 15 | .25 | 190,000 | 920 | 1 : 8 | do. | do. | 3300 | 195 | 1900 |80° vertical angle lens, 2 sides of 4 panels each, mercury | | | | | | | | | | | | | rotation. | | Sunderland | Single flash | 5 | .10 | 175,000 | 500 | Nearly 1 : 2| do. | "Chance" 55 mm. | 1200 | 83 | 1903 |Mercury rotation; univalve 164° in azimuth, with 164° | | | | | | | | | dia. mantle | | | | dioptric mirror in rear. | | Near Firth of Tay | Red and white| 60 | .50 | 392,000 | 920 and | White about | do. | "Chance" 55 mm. | 1200 | 93 | 1902 |Combined hyper-radial and first-order light with back | |flashes alter-| | | | 1330 | 1 : 9 | | dia. mantle | | | | prisms in white and mirrors in red. Revolves in 60 | |nately every | | | | | red about | | | | | | secs. | | 30 secs. | | | | | 1 : 2.2 | | | | | |[Holy Island, 1905 (Lamlash), similar, flash every 15 secs.] | Aberdeenshire | Single flash | 15 | .50 | 881,000 | 920 and | 1 : 2.2 | do. | do. | 2150 | 120 | 1903 |Composite apparatus; panels of 1330 mm. and 920 mm. | | | | | | 1330 | | | | | | | focal distance; 2 faces. | | Dornoch Firth | 6 flash | 30 | .50 | 89,000 | 700 | 1 : 12 | do. | "Chance" 55 mm. | 1200 | 175 | 1892 |6 panels (lens) of 30° with 180° mirror. | | | | | | | | | dia. mantle | | | | [Douglas Head (Isle of Man) similar.] | | West of Orkneys | 3 flash | 30 | 1.0 | 378,000 | 1330 | 1 : 9 | do. | "Chance" 85 mm. | 2150 | 113 | 1895 |Equiangular lenses. | | | | | | | | | dia. mantle | | | | | | South end of Arran| 3 flash | 30 | .50 | 597,000 | 1330 | 1 : 6 | do. | do. | 2150 | 130 | 1901 |3 equiangular lens panels with mirror in rear; side panels | | Island | | | | | | | | | | | | eccentric. | | | | | | | | | | | | | [Hyskin Rocks (1904) similar.] | | Co. Donegal | 3 flash | 60 | 3.0 | 17,000 to | 1330 | 1 : 6 | Coal Gas | Wigham, 108 jets | 2300 | 130 | 1887 |Triform apparatus, vertical angle of lenses 65°; 6 sides, | | | | | 326,000 | | | | (maximum) | (max.) | | | one revolution in 6 minutes. The single flash from | | | | | | | | | | | | | lens is divided by eclipsing burner into 3 flashes. | | Co. Cork | Single flash | 5 | .17 | 750,000 | 920 | 1 : 4 | Incandescent| Irish pattern | 1200 | 160 | 1904 |Biform apparatus; 4 panels of 90° vertical angle and 90° | | | | | | | | petroleum | 50 mm. mantle | | | | in azimuth; mercury rotation. | | | | | | | | vapour | | | | | | | do. | 2 flash | 10 | .25 | 460,000 | 920 | 1 : 6 | do. | do. | 1200 | 236 | 1907 |Biform apparatus, 3 sides each of 2 panels; vertical | | | | | | | | | | | | | angle 96°; mercury rotation. | | | | | | | | | | | | |[St. John's Point, Co. Down (1908) similar, period 7.5 secs.]| Dublin Bay | Single flash | 30 | 1.0 | 950,000 | 920 | 13 : 32 | do. |Irish pattern 3-50| 3300 | 134 | 1902 |Bivalve apparatus; panels of 147° in azimuth and 122° | | | | | | | | | mm. dia. mantles | | | | vertical angle; mercury rotation. | | | | / 1.0 | 70,000 | 920 | 1 : 8 | Oil | 6 wick | 480 | 164 | 1891 |\ | | | || .50 | 180,000 | 920 | 1 : 8 | Incandescent| / 30 mm. dia. | 400 | 164 | 1895 | |The old first-order apparatus has been utilized in all | | Bay of Biscay | Single flash | 10 || | | | | oil gas | | mantle | | | | | cases. | | | || .70 | 360,000 | 920 | 1 : 8 | Incandescent| | 55 mm. dia. | 1300 | 164 | 1902 | | | | | | \ | | | | acetylene | \ mantle | | | |/ | | English Channel | Single flash | 20 | 1.0 | 400,000 | 1330 | 1 : 6 | Incandescent| French pattern | 2150 | 394 | 1894 |Mercury rotation, hyper-radial apparatus with reflecting | | | | | | | | petroleum | 85 mm. mantle | | | | prisms. This is the only apparatus of this focal | | | | | | | | vapour | | | | | distance on the French coast. | | Finistère | 4 flash | 25 | .37 | 200,000 | 920 | 1 : 8 | do. | do. | 2150 | 223 | 1900 |Group-flashing apparatus; 4 panels of 45°, with 180° | | | | | | | | | | | | | mirror in rear; mercury rotation. | | do. | 3 flash | 20 | .38 | 200,000 | 700 | 1 : 5 | do. | do. | 2150 | 94 | 1897 |Mercury rotation; 3 panels, mirror in rear. | | Mediterranean | Single flash | 5 | .38 | 250,000 | 700 | 1 : 4 | do. | do. | 2150 | 229 | 1902 |Mercury rotation. | | Finistère | Single flash | 5 | .38 | 500,000 | 700 | 1 : 4 | do. | do. | 2150 | 252 | 1902 |Twin optic; mercury rotation. | Bombay | 2 flash | 10 | .25 | 250,000 | 920 | Nearly 1:4 | do. |70 mm. dia. mantle| 1400 | 153 | 1902 |Mercury rotation; bivalve apparatus; 2 double-flashing | | | | | | | | | | | | | 170° panels. | | Newfoundland | Single flash | 7.5 | .30 | 1,100,000 | 1330 | 1 : 4 | do. | "Chance" 85 mm. | 2150 | 165 | 1907 |4 panels, vertical angle 121½°; mercury rotation. | | | | | | | | | dia. mantle | | | | [Manora Point, Karachi, 1909, similar.] | | British Columbia | 2 flash | 7.5 | .44 | 220,000 | 920 | 1 : 8 | do. | do. | 2150 | .. | 1908 |Mercury rotation. 4 sides of 2 panels each. | | Cape Colony | Single flash | 3 | .31 | 30,000 | 250 | 1 : 3 | do. | "Chance" 55 mm. | 1200 | 175 | 1904 |3 panels, vertical angle 150°; mercury rotation. | | | | | | | | | dia. mantle | | | | | do. | 4 flash | 40 | .58 | 200,000 | 920 | 1 : 8 | do. | "Chance" 85 mm. | 2150 | 180 | 1895 |Mercury rotation; 4 panels of 45° in azimuth and 80° | | | | | | | | | dia. mantle | | | | vertical angle, with catadioptric mirror in rear. | West Australia | 2 flash | 10 | .15 | 450,000 | 920 | About 1 : 3 | do. | do. | 2150 | 404 | 1904 |Mercury rotation; 2 lenses of 126½° in azimuth, with | | | | | | | | | | | | | mirror of 107°. | do. | Single flash | 5 | .30 | 300,000 | 700 | 1 : 3 | do. | do. | 2150 | 190 | 1909 |Mercury rotation; 3 panels, each 120° in azimuth and | | | | | | | | | | | | | 133½° vertical angle. | |Connecticut, U.S.A.| 2 flash | 30 | .50 | 10,000 | 250 | 1 : 4 | do. |34 mm. dia. mantle| 300 | 54 | 1906 |Rotated on ball bearings. 2 lenses of 90° each and | | | | | | | | | | | | | mirror. | | New York, U.S.A. | Single flash | 60 | 4.0 | 250,000 | 920 | 1 : 8 | do. |55 mm. dia. mantle| 1000 | 167 | 1858 |Rotated on roller bearings. | |Washington, Pacific| Alternating | 5 | .20|White 10,000| 500 | .. | Oil | 3 wick | 160 | 122 | 1898 |Mercury rotation; one (red) lens of 170° in azimuth, re- | | Coast, U.S.A. | red and white| | | red 8,000 | | | | | | | | inforced by two 60° mirrors; one (white) lens of 60° in | | flashes | | | | | | | | | | | azimuth. | -------------------+--------------+-------+--------+------------+---------+-------------+-------------+------------------+----------+-------+----------+-------------------------------------------------------------+

* The dates given are of the establishment of the optical apparatus. In many cases incandescent burners have been installed at later dates.

_English Colonies._--In Canada the coast lighting is in the hands of the minister of marine, and in most other colonies the public works departments have control of lighthouse matters.

_Other Countries._--In Denmark, Austria, Holland, Russia, Sweden, Norway and many other countries the minister of marine has charge of the lighting and buoying of coasts; in Belgium the public works department controls the service.

In the Trinity House Service at shore lighthouse stations there are usually two keepers, at rock stations three or four, one being ashore on leave. When there is a fog signal at a station there is usually an additional keeper, and at electric light stations a mechanical engineer is also employed as principal keeper. The crews of light-vessels as a rule consist of 11 men, three of them and the master or mate going on shore in rotation.

The average annual cost of maintenance of an English shore lighthouse, with two keepers, is £275. For shore lighthouses with three keepers and a siren fog signal the average cost is £444. The maintenance of a rock lighthouse with four keepers and an explosive fog signal is about £760, and an electric light station costs about £1100 annually to maintain.

A light-vessel of the ordinary type in use in the United Kingdom entails an annual expenditure on maintenance of approximately £1320, excluding the cost of periodical overhaul.

AUTHORITIES.--Smeaton, _Eddystone Lighthouse_ (London, 1793); A. Fresnel, _Mémoire sur un nouveau system d'éclairage des phares_ (Paris, 1822); R. Stevenson, _Bell Rock Lighthouse_ (Edinburgh, 1824); Alan Stevenson, _Skerryvore Lighthouse_ (1847); Renaud, _Mémoire sur l'éclairage et le balisage des côtes de France_ (Paris, 1864); Allard, _Mémoire sur l'intensité et la portée des phares_ (Paris, 1876); T. Stevenson, _Lighthouse Construction and Illumination_ (London, 1881); Allard, _Mémoire sur les phares électriques_ (Paris, 1881); Renaud, _Les Phares_ (Paris, 1881); Edwards, _Our Sea Marks_ (London, 1884); D. P. Heap, _Ancient and Modern Lighthouses_ (Boston, 1889); Allard, _Les Phares_ (Paris, 1889); Rey, _Les Progrès d'éclairage des côtes_ (Paris, 1898); Williams, _Life of Sir J. N. Douglass_ (London, 1900); J. F. Chance, _The Lighthouse Work of Sir Jas. Chance_ (London, 1902); de Rochemont and Deprez, _Cours des travaux maritimes_, vol. ii. (Paris, 1902); Ribière, _Phares et Signaux maritimes_ (Paris, 1908); Stevenson, "Isle of May Lighthouse," _Proc. Inst. Mech. Engineers_ (1887); J. N. Douglass, "Beacon Lights and Fog Signals," _Proc. Roy. Inst._ (1889); Ribière, "Propriétés optiques des appareils des phares," _Annales des ponts et chaussées_ (1894); Preller, "Coast Lighthouse Illumination in France," _Engineering_ (1896); "Lighthouse Engineering at the Paris Exhibition," Engineer (1901-1902); N. G. Gedye, "Coast Fog Signals," _Engineer_ (1902); _Trans. Int. Nav. Congress_ (Paris, 1900, Milan, 1905); _Proc. Int. Eng. Congress_ (Glasgow, 1901, St Louis, 1904); _Proc. Int. Maritime Congress_ (London, 1893); J. T. Chance, "On Optical Apparatus used in Lighthouses," _Proc. Inst. C.E._ vol. xxvi.; J. N. Douglass, "The Wolf Rock Lighthouse," ibid. vol. xxx.; W. Douglass, "Great Basses Lighthouse," ibid. vol. xxxviii.; J. T. Chance, "Dioptric Apparatus in Lighthouses," ibid. vol. lii.; J. N. Douglass, "Electric Light applied to Lighthouse Illumination," ibid. vol. lvii.; W. T. Douglass, "The New Eddystone Lighthouse," ibid. vol. lxxv.; Hopkinson, "Electric Lighthouses at Macquarie and Tino," ibid. vol. lxxxvii.; Stevenson, "Ailsa Craig Lighthouse and Fog Signals," ibid. vol. lxxxix.; W. T. Douglass, "The Bishop Rock Lighthouses," ibid. vol. cviii.; Brebner, "Lighthouse Lenses," ibid. vol. cxi.; Stevenson, "Lighthouse Refractors," ibid. vol. cxvii.; Case, "Beachy Head Lighthouse," ibid. vol. clix.; _Notice sur les appareils d'éclairage_ (French Lighthouse Service exhibits at Chicago and Paris) (Paris, 1893 and 1900); _Report on U.S. Lighthouse Board Exhibit at Chicago_ (Washington, 1894); _Reports of the Lighthouse Board of the United States_ (Washington, 1852, et seq.); British parliamentary reports, _Lighthouse Illuminants_ (1883, et seq.), _Light Dues_ (1896), _Trinity House Fog Signal Committee_ (1901), _Royal Commission on Lighthouse Administration_ (1908); _Mémoires de la Société des Ingénieurs Civils de France_, _Annales des ponts et chaussées_ (Paris); _Proc. Inst. C. E._; _The Engineer_; _Engineering_ (_passim_). (W. T. D.; N. G. G.)

FOOTNOTES:

[1] A full account is given in Hermann Thiersch, _Pharos Antike, Islam und Occident_ (1909). See also MINARET.

[2] In 1901 one of the lights decided upon in 1886 and installed in 1888--Créac'h d'Ouessant--was replaced by a still more powerful twin apparatus exhibited at the 1900 Paris Exhibition. Subsequently similar apparatus to that at Créac'h were installed at Gris-Nez, La Canche, Planier, Barfleur, Belle-Île and La Coubre, and the old Dunkerque optic has been replaced by that removed from Belle-Île.

[3] Both the Talais and Snouw light-vessels have since been converted into unattended light-vessels.

[4] For the purposes of the mariner a light is classed as flashing or occulting solely according to the duration of light and darkness and without any reference to the apparatus employed. Thus, an occulting apparatus, in which the period of darkness is greater than that of light, is classed in the Admiralty "List of Lights" as a "flashing" light.

[5] The Flamborough Head rocket was superseded by a siren fog signal in 1908.

LIGHTING. Artificial light is generally produced by raising some body to a high temperature. If the temperature of a solid body be greater than that of surrounding bodies it parts with some of its energy in the form of radiation. Whilst the temperature is low these radiations are not of a kind to which the eye is sensitive; they are exclusively radiations less refrangible and of greater wave-length than red light, and may be called infra-red. As the temperature is increased the infra-red radiations increase, but presently there are added radiations which the eye perceives as red light. As the temperature is further increased, the red light increases, and yellow, green and blue rays are successively thrown off. On raising the temperature to a still higher point, radiations of a wave-length shorter even than violet light are produced, to which the eye is insensitive, but which act strongly on certain chemical substances; these may be called ultra-violet rays. Thus a very hot body in general throws out rays of various wave-length; the hotter the body the more of every kind of radiation will it throw out, but the proportion of short waves to long waves becomes vastly greater as the temperature is increased. Our eyes are only sensitive to certain of these waves, viz. those not very long and not very short. The problem of the artificial production of light with economy of energy is the same as that of raising some body to such a temperature that it shall give as large a proportion as possible of those rays which the eye is capable of feeling. For practical purposes this temperature is the highest temperature we can produce. As an illustration of the luminous effect of the high temperature produced by converting other forms of energy into heat within a small space, consider the following statements. If burned in ordinary gas burners, 120 cub. ft. of 15 candle gas will give a light of 360 standard candles for one hour. The heat produced by the combustion is equivalent to about 60 million foot-pounds. If this gas be burned in a modern gas-engine, about 8 million foot-pounds of useful work will be done outside the engine, or about 4 horse-power for one hour. If this be used to drive a dynamo for one hour, even if the machine has an efficiency of only 80%, the energy of the current will be about 6,400,000 foot-pounds per hour, about half of which, or only 3,200,000 foot-pounds, is converted into radiant energy in the electric arc. But this electric arc will radiate a light of 2000 candles when viewed horizontally, and two or three times as much when viewed from below. Hence 3 million foot-pounds changed to heat in the electric arc may be said roughly to affect our eyes six times as much as 60 million foot-pounds changed to heat in an ordinary gas burner.

Owing to the high temperature at which it remains solid, and to its great emissive power, the radiant body used for artificial illumination is usually some form of carbon. In an oil or ordinary coal-gas flame this carbon is present in minute particles derived from the organic substances with which the flame is supplied and heated to incandescence by the heat liberated in their decomposition, while in the electric light the incandescence is the effect of the heat developed by the electric current passed through a resisting rod or filament of carbon. In some cases, however, other substances replace carbon as the radiating body; in the incandescent gas light certain earthy oxides are utilized, and in metallic filament electric lamps such metals as tungsten or tantalum.

1. OIL LIGHTING

Vegetable and animal oils.

From the earliest times the burning of oil has been a source of light, but until the middle of the 19th century only oils of vegetable and animal origin were employed in indoor lamps for this purpose. Although many kinds were used locally, only colza and sperm oils had any very extended use, and they have been practically supplanted by mineral oil, which was introduced as an illuminant in 1853. Up to the latter half of the 18th century the lamps were shallow vessels into which a short length of wick dipped; the flame was smoky and discharged acrid vapours, giving the minimum of light with the maximum of smell. The first notable improvement was made by Ami Argand in 1784. His burner consisted of two concentric tubes between which the tubular wick was placed; the open inner tube led a current of air to play upon the inner surface of the circular flame, whilst the combustion was materially improved by placing around the flame a chimney which rested on a perforated gallery a short distance below the burner. Argand's original burner is the parent form of innumerable modifications, all more or less complex, such as the Carcel and the moderator.

[Illustration: FIG. 1.]