Lighthouses of Great Britain
No detailed history of any early modern use of electric carbon arc lamps in lighthouses of Great Britain seems to be readily available. If diligently researched, the stories can be found in bits and pieces of electrical material in old newspapers, magazines, letters, official papers, reports, and a few books. However, the average lighthouse enthusiast has no convenient means to acquire this rare information or put it together for a good understanding. Therefore, we will try to do so, in a series of short Web page articles on the various electric carbon arc lighthouses that once helped the nineteenth-century mariner to sail safely on his way.
The electric arc light, superior to any known means of illumination since antiquity, was rediscovered in the eighteenth century, but it did not receive widespread public attention until 1808, when Sir Humphrey Davy used a powerful battery of electric cells to demonstrate the light at the Royal Society. However, for decades thereafter, it hardly left the laboratory because powerful batteries were often considered too expensive for use in electric lighting, which consumed a substantial amount of power.
Nevertheless, by the 1850’s, a practical electro-mechanical power source, in the form of the magneto-electric generator powered by a steam engine, became available; so the electric arc lights, comparable to the brilliancy of the sun, were proposed as a viable solution to the visibility problems with dim oil lamps currently illuminating lighthouse beacons. “Now the magneto-electric spark presents strong claims to attention, from its remarkable brilliancy and splendor, rivaling, if not indeed surpassing, in intensity the solar light itself; for according to Dr. Gladstone, the electric light bears to the solar light a ratio of seven to six,” stated a report on “the Application of the Magneto-Electric Light to Lighthouse Illumination,” by D. & T. Stevenson, Engineers to the British Northern Lighthouse Board. “It is therefore highly important that its applicability to lighthouse illumination should be fully tested.”
On the left above is a fixed type of electric carbon arc light for lighthouse use and on the right is an 1867 magneto-electric generator designed by Professor F. H. Holmes in 1867. It was installed four years later in the British Souter Point Lighthouse, illustrated below, with its huge fog horns that sounded out a blast of four seconds every minute when its light failed to pierce a foggy atmosphere. Its armature shaft carried 96 coils. Arranged radially round the armature were 56 compound magnets, whose poles projected into the spaces between the rings carrying the coils. The three-ton generator ran at 4oo revolutions per minute and gave a mean light of 1,520 candlepower.
The first experiments with the new electric light began in England on December 8, 1858, in the relatively new South Foreland Lighthouse on the eastern end of the Straits of Dover. A Duboscq regulator maintained the proper separation of the carbons for the electric light to sustain its arc in the first-class dioptric lens, and a three horsepower steam engine driving a Holmes’ magneto-generator at 90 r. p. m. supplied the power. The first trials were disappointing and discontinued, but they were resumed in March of 1859 and ran into the early months of 1860. The light was apt to go out several times during the night, so an extra attendant was required to continuously monitor it. He could easily restart it at a touch, and the tests were finally considered successful.
After necessary repairs and alterations were made to the equipment, it was removed and erected in the British lighthouse at Dungeness, at the western end of the Straits of Dover in February 1862. However, the 19,000 candlepower beacon was not exhibited until June 6, 1862 because three more men had to be added to the lighthouse staff, and it was difficult to obtain qualified keepers.
Locations of some of the nineteenth-century European lighthouses
that brandished electric carbon arc beacons (Hornum excluded)
A description on the Dungeness lighthouse arrangement was included in a long, official report dated December 1, 1865, and an excerpt from it, which might interest our readers, runs as follows:
“In the light-room at Dungeness, there are two sets of optical apparatus, one the old reflectors formerly in use, which are kept always ready for being lighted in case of accident; and the other the dioptric apparatus for the electric light, which is placed in the upper part of the lantern. It was stated that since the establishment of this new method of illumination, the old reflectors have been occasionally used in consequence of accidents or from other causes, and on one occasion for a period of six hours.
“The generating machinery of the electric light consists, as has been explained by Professor Holmes, of a number of powerful magnets, which are fixed round an octagonal frame, and of rods of soft iron with copper wires coiled round them, called bobbins or helices, which are made to rotate in the interior of the frame in which the magnets are fixed. Powerful electric currents are generated by the successive transit of the bobbins or helices, past the magnets. The positive and negative electric currents thus generated are conveyed by copper wires from the engine-room on the ground floor up to the lamp which is in the light-room, but the alternate currents are reversed before they reach the flame, by means of what is called a commutator.
“The lamp itself is constructed to receive two carbon rods, which by an ingenious automatic contrivance, depending on the strength of the currents, are preserved at a nearly constant distance from each other. The resistance to the currents formed at the carbon points produces the electric light, the power of which depends on the distance between the ends of the carbons, and the great difficulty which has to be encountered is to regulate and preserve continuously the proper distance between the carbons. The lamps, of which there are two always in the light-room and two always in reserve, can be placed in the focus of the optical apparatus with the greatest ease and celerity.
“The apparatus used at Dungeness is a fixed dioptric one of the sixth order, having a small silvered reflector placed on the landward side, so as to increase the divergence. For the better regulation of the position of the flame in regard to the horizon, a permanent mark has been made on the inside of the lantern, so that the light-keeper, by looking at the beam of light which falls upon the lantern, can at once perceive whether the best part of the beam is passing above or below the horizon line.
“In the engine-house adjoining the tower, there are two steam engines for producing the revolution of the frame which carries the bobbins or helices. These engines are each of six horse-power and both of them are constantly required for the production of the light. With regard to the consumption of the carbons, it was stated that in winter it amounts to about 200 lineal feet per month, and in summer from 120 to 130 feet, being on an average equal to about four lineal feet per night.
“It was stated that the most defective part of the apparatus, and that which undoubtedly occasions the greatest trouble, is the regulation of the lamp, so as to secure the proper amount of separation of the carbon points.”
This, along with the negligence of lighthouse keepers, occasionally allowed the light to go out, which was a serious offense that placed the lives of mariners in jeopardy. An example of failure of the light is expressed in an interesting letter, dated Ramsgate, 22 February 1866, which also gives us a unique peak into a British electric lighthouse operation at the time. L. W. Vaile addressed it to P. H. Berthon, Esq. Secretary, Trinity House, which was the Board that supervised British lighthouse operations, and therein he wrote:
“I beg to acquaint you, for the information of the Board, that in compliance with the instructions conveyed in your telegram of the 20th instant, I visited the Dungeness light-house to investigate into the cause of the light being out on the morning of the 15th instant. As previously reported, Mr. Westmorland, went to sleep on his watch, a new carbon having shortly before been placed in the holder, which raised the holder above the lens; in working down, the holder caught upon the corner of the lens, thus separating the carbons and causing the light to go out. Mr. Westmorland acquaints me he awoke himself, and find the light out, proceeded up the steps to the lamp, causing it to snake, which brought the holder clear of the lens, and the carbons coming together the light resumed burning of itself. As the carbon holders work very close to the lens, this accident is very liable to happen, but had the keep been awake the light would not have been out for more than a few seconds. Mr. Watson was on watch, and in the boiler-house, sitting in a chair, reading the newspaper, when one of the coast-guard knocked at the door and acquainted him something was wrong with the light; he proceeded outside immediately, but at this instance the light resumed burning, as previously stated.
“I called all the engineers into my presence, and asked them how often they went into the engine room in the course of the watches. They said they looked frequently in; but went in generally two or three times, when if necessary, they put a little oil to the engine, or wiped the machines. Had Mr. Watson looked at the machines during the time the light was out (if out from the cause stated, the carbons being separated), he must have observed it, as the whole of the light must have been flashing off from the machines; but being occupied, his attention being taken up by reading the paper, he did not observe it. I asked the engineers if it was usual for them to read on watch? They all answered, ‘Yes; that when everything about the engines and machines were working satisfactorily, they sat down and read, and they considered that, should there be any falling off of the light, it was the duty of the keeper in the lantern to direct their attention by calling down the tube, and acquainting them of it. They did not consider it at all their duty, so long as the engines and machines were working satisfactorily, to look after the light, although they occasionally did, by going outside and looking up at the lantern; and if they observed any apparent falling off, they would call to the keeper in the lantern; but they did not consider themselves at all responsible for any neglect on his part.’ I asked them if they thought that when reading, they were attending properly to their duties? They answered, ‘Yes; that reading kept them from feeling drowsy, which they should do, if they had no occupation; and that, should anything go wrong with the working of the engines or machines, whilst so doing, their attention would be attracted to it immediately.’ I asked Mr. Lane, the senior assistant keeper, whether on his watch in the lantern he occupied himself in any other way than in attending to the lamp, he answered, ‘Yes, he generally read, but had been lately repairing signals; but should there be any falling off of the light, he would observe it immediately whilst so employed.’”
Needless to say, for an offense as serious as letting the fire in “this most important light” go out for 15 minutes, Mr. Vaile recommended that the light-keeper on duty, Mr. Westmorland, be dismissed, especially since this was not the first time he neglected his duty. Regardless of this instance, further lighthouse keepers’ failures, the difficulty in acquiring competent personnel, and frequent mechanical breakdowns, this famous electric beacon at one of the electric carbon arc lighthouses of Great Britain continued in service for a decade.
For much more on ancient lighthouses, read The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting.
This page was last modified on Tuesday, December 06, 2016