May 30, 1889] 



NATURE 



III 



■service to manners in various parts of the world. For the more 

 important stations at sea where light-vessels are now employed 

 the system is considered to be yet wanting in that trustworthi- 

 ness which should be the leading characteristic of all coast 

 lighting. Very important experiments have lately been made 

 by the Lighthouse Board of the United Stales, at their CJeneral 

 Depot at Tompkinsville, New York, with buoys lighted 

 electrically by glow lamps, operated through submarine c m- 

 ductors from the shore. These experiments have proved so 

 successful that an installation for marking the Gedney's Channel 

 entrance of Lower Bay, New York Harbour, with six buoys and 

 lOO-candle glow lamps, was lighted on Novemb-r 7 last. Gas 

 buoys were considered inapplicable for this special case, owing 

 to their f)rm and size rendering them liable to break adrift, 

 particularly when struck by floating ice or passing vessels. The 

 buoy adopted for the service consists of a spar 46 feet long, 

 having its lower end shackled direct to a heavy iron sinker, resting 

 on the bottom. At the upper end the buoy is fitted with an iron 

 cage inclosing a heavy glass jar, in which is placed the glow lamp 

 ■of 100 candle units intensity. The cable is secured by wire staples 

 lin a deep groove cut in the buoy and covered by a strip of wood. 

 'For a distance of several feet at the lower end of the buoy the 

 "Cable is closely served with iron wire, over which is wound spun 

 •yarn to prevent injury from chafing on the shackle and sinker. The 

 •central station on shore, with steam-engines and dynamos in 

 duplicate, is on Sandy Hook, at a distance from the extreme 

 buoys of about 3 nautical miles. The installation is reported to 

 be working continuously and successfully. For auxiliary or port 

 lights on shore where no collisions can occur, the Pintsch gas 

 system is found to be very perfect. At Broadness, on the 

 Thames, near Gravesend, the Trinity House erected in 1885, an 

 automatic lighthouse illuminated on Pintsch's system, as shown 

 by the diagram. This small lighthouse shows a single flashing 

 light at periods of ten seconds, the flashes having an intensity of 

 500 candle units. The flashes and eclipses are produced with 

 perfect regularity by special clockwork, which also turns on the 

 gas supply to the burner at sunset and off again at sunrise. It 

 is also arranged for periodic adjustment for the lengthening and 

 shortening of the nights throughout the year. This automatic 

 light is in the charge of a boatman, who visits it once a week, 

 when he cleans and adjusts the apparatus, and cleans the glazing 

 of the lantern. An automatic lighthouse similar to that at 

 Broadness has been lately installed at Sunderland by the River 

 Wear Commissioners, on a pier which is inaccessible during 

 stormy weather. In 1881-82 several beacons automatically 

 lighted by petroleum spirit, on the system of Herr Lindberg 

 and Herr Lyth, of Stockholm, were established by the Swedish 

 lighthouse authorities, and are reported to be working efficiently. 

 In 1885 a beacon or automatic lighthouse on this system was 

 installed by the Trinity House on the Thames, near Gravesend, 

 and has been found to work efficiently. The light is occulting 

 at periods of about two seconds ; the occultations are produced by 

 an opaque screen, rotated around the light by the ascending 

 currents of heated air from the lamp acting on a horizontal fan. 

 As there is no governor to the apparatus, the periods of the 

 occultations are subject to slight errors compared with those of 

 the gas light controlled by clockwork. In 1844 an iron beacon 

 lighted by a glow lamp and the current from a secondary battery 

 was erected on a tidal rock near Cadiz. Contact is made and 

 broken by a small clock, which runs for twenty-eight days, and 

 causes the light to flash for five seconds at periods of half a 

 minute. The clock is also arranged for eclipsing the light 

 between sunrise and sunset. The apparatus is the invention of 

 Don Isaas Lavaden, of Cadiz, to whom I am indebted for kindly 

 showing me the light in action when on a visit to Cadiz in 1885. 

 There is every probability that automatic beacons lighted either by 

 electricity, gas, or petroleum spirit, will in consequence of their 

 economy in maintenance be extensively adopted in the future. 



Coal and wood fires, the flames produced by the combustion 

 of tallow, nearly all the animal, vegetable, and mineral oils, coal 

 and oil gas, and the lime-light, have been employed from time 

 to time in lighthouse illumination, and last but not least, the 

 electric light. None of these illuminants have received such 

 universal application in all positions both ashore and afloat as 

 mineral oil at the present moment, and justly so, when we con- 

 sider its efficiency and economy for the purpose. So recently 

 as 1822, the last beacon coal fire in this country was replaced by 

 a catoptric oil light, at Saint Bees Lighthouse, on the coast of 

 Cumberland. We have here diagrams of two of these coal fire 

 beacons, one of them designed and erected by Smeaton in 1767 



on his lighthouse at the Spurn Point, on the east side of the 

 entrance to the. Humber. So late as 1845, sjierm oil was 

 entirely used in the lighthouses and light-vessels of the Trinity 

 House ; but, shortly afterwards, colza was adopted with the 

 same efficiency, and with a saving in annual cost of about 44 per 

 cent. In 1861, experiments were made by the Trinity House 

 for determining the relative efficiency and economy of colza 

 and mineral oil for lighthouse illumination ; but owing to the 

 imperfect refinement of the best samples of the latter then pro- 

 curable in the market, together with its high price, the result of 

 the investigation was not so satisfactory as to justify a change 

 from colza. In 1869, the price of mineral oil of gojd illumin- 

 ating quality, and safe flashing-point, was found to be procurable 

 at about half the price of colza, when the Trinity House deter- 

 mined to make a further series of experiments, and by the^e it 

 was ascertained that, with a few simple modifications of the 

 argand burners then in use, they were rendered very efficient 

 for the purpose ; it was also found that these burners were thus 

 considerably improved for the combustion of colza. A change 

 from colza to mineral oil was then CDmmenced, and mineral 

 oil is now generally adopted in the lighthouses and light- 

 vessels of the Trinity House service ; and with even greater 

 economy than was at first anticipated, the price of this illu- 

 minant being now rather less than one-third that of colza. 

 The most powerful oil burner then in use was one of four con- 

 centric wicks, the joint production of Arago and Fresnel, and 

 adopted by the French lighthouse authorities about the year 

 1825, in conjunction with the then new dioptric system of optical 

 apparatus of Fresnel. The standard intensity of the combined 

 flames of this burner, one of which we have here, was 260 candle 

 units. A further development was made during the experiments 

 of the Trinity House in 187 1, by increasing the number of wicks 

 from four to six, which more than doubled the intensity of the 

 light, while effecting a condensation of the luminary per unit of 

 focal area, or, in other words, improved the optical efficiency 70 

 per cent. We have here also one of these burners. 



I* have since devised an argand burner for the combustion of 

 all illuminating gases and oils, whereby still further condensation 

 of the flames, together with greater intensity and economy of 

 combustion, is obtained, and the glass chimney is protected from 

 breakage. These improvements are effected by a special ar- 

 rangement and distribution of the air currents through the rings 

 of flame, and between them and the glass chimney. We are 

 thus enabled on this system to increase the dimensions of 

 lighthouse burners, for gas and oil, for ten or more rings of 

 flame. With ten rings, we obtain an aggregate intensity, when 

 burning cannel gas and good mineral oil, of considerably over 

 2000 candle units, while the improved efficiency of the luminary 

 for optical cendensation of the radiant light per unit of focal area, 

 as compared with the luininary of the Fresnel four-wick oil 

 burner, has been in each case increased 109 per cent. With 

 reference to the perfect combustion of these highly condensed 

 flames, I may state that the efficiency for gas is exactly double 

 that of the London standard argand burner, viz. when con- 

 suming gas of the London standard of sixteen candles, the light 

 produced is at the rate of 6'4 instead of 32 candles per cubic 

 foot. In addition to a single ring gas burner of this type we 

 have two burners of Ihe ten rings of flames, and models of their 

 flames, one for gas and the other for mineral oil. These burners 

 are all of the Trinity House new pattern, both gas and oil, and 

 they are of the same general arrangement for combustion, except 

 that the oil burner is provided with cotton wicks. Both produce 

 flames of nearly the same form, dimensions, intensity, and colour. 



The first application of coal gas to lighthouse illumination 

 was made at the Troon Lighthouse, Ayrshire, in 1827 ; and in 

 1847 it was adopted at the Hartlepool Lighthouse, Durham, 

 where for the first time it was employed in combination with 

 dioptric apparatus of the first order of Fresnel. The slow pro- 

 gress made with coal gas in lighthouses, except for harbour lights, 

 where the gas could be obtained in their vicinity, as at 

 Hartlepool, was chiefly due to the great cost incurred in the 

 manufacture of the small quantity required, and at the usual 

 isolated positions occupied by coast lighthouses, involving extra 

 cost both for labour, and for the extra transport of the coal. lu 

 1865, the attention of lighthouse authorities was directed to gas, 

 afe an illuminant for lighthouses, by Mr. John R. Wigham, of 

 Dublin, whose system was tried in that year, at the Howth 

 Bailey Lighthouse, Dublin Bay. The gas burner of Mr. 

 Wigham, one of which we have here, consists of seven con- 

 cern ric rings, of single flat-flame burners, amounting in the 



