Canadian Historic Sites: Occasional Papers in Archaeology and History No. 9
by Edward F. Bush
Apparatus: Lights and Optics
The Whale-oil Lamp
The principal handicap of the oil-fed lamp has always been the smoking of the wick, depositing a film of soot on the lantern glazing and so decreasing rapidly the effectiveness of the light. This centuries-old problem was overcome in 1782 by an invention by the Swiss, Ami Argand, of a virtually smokeless oil lamp utilizing a circular, sleeve-like wick through and around which was a free circulation of air, much improving combustion. The lamp, soon to be known by the name of its inventor, was enclosed within a glass chimney reminiscent of the coal-oil lamps used by our grandparents before the age of hydro. The Argand burner produced a clear, relatively smoke-free flame. By 1820 some 50 lighthouses along the shores of England and Ireland were fitted with Argand lamps; indeed 60 years later there were still numerous lighthouses in the British Isles so equipped.1 A further refinement and improvement of the simple Argand burner was the multiple-wick lamp devised by Count Rumford (Sir Benjamin Thompson), American-born scientist and founder of the Royal Institution in 1800.
Parabolic Reflectors: Catoptric Principle
The whale-oil lamp on the Argand principle was still inferior in illuminating properties to a well-tended blazing coal or wood fire. To remedy this deficiency, the Swedes hit upon the use of the parabolic reflector of polished steel as early as 1738, in order to focus the light on the required plane. At Orskar, five parabolic mirrors were fitted with ten burners, but these initial experiments were disappointing mainly because the lamps were not set at the exact focal point of the mirrors.2 By 1763 a crude type of parabolic reflector was introduced to certain lights along the Mersey in England, but again results were not encouraging.3 It fell to J. A. Bordier-Marcet of France to perfect what came to be known as the "catoptric system" (from the Greek katoptron, a mirror). His fanal à double effet employing two reflectors and two Argand lamps won general favour in the French lighthouse service by 1819. Bordier-Marcet's next optic, the fanal sidéral or star-lantern, utilized two circular reflecting metal plates, one above and one below the flame, projecting the light in a parabolic curve horizontally. In essence, this device reflected the vertically emitted light to the horizontal plane. Mariners at Honfleur, where the star-lantern was first introduced, enthusiastically dubbed it notre salut. This device increased the candle power of an ordinary Argand lamp from 10 to 70 candlepower, a seven fold improvement.4 Catoptric apparatus was used in the Canadian lighthouse service until late in the century because of its relative economy, but in Europe and the United States a light upon an improved principle had largely displaced the simple reflector type by the 1830s and 1840s.
The following passage quoted from the minutes of the New Brunswick Executive Council in 1846, describing the apparatus at Machias Seal Island at the entrance to the Bay of Fundy, illustrates the limitation of the older style catoptric installations with multiple lamps and reflectors.
By contrast, the largest dioptric light of much greater power than the above installation, 6 feet in diameter with but one lamp, was many times more convenient to service.
Lenses: Dioptric Principle
In 1823 another Frenchman, Augustin Fresnel, perhaps the most celebrated of all the pioneers in lighthouse optics, introduced the first lenticular, or dioptric, lighting apparatus in the Corduouan lighthouse located at the mouth of the Gironde River. The principle of the dioptric (Greek dioptrikos, to see through) system was the refraction, by means of lenses and prisms, of light on the desired focal plane. Unlike the catoptric, the dioptric apparatus used only one lamp or light source. At the time of the installation of the first lenticular light in the Corduouan lighthouse in 1823, the facility was considered second to none in the world. The cutting and grinding of lenses called for craftsmanship of a very high order, and so lenticular apparatus was costly, but once installed it required no adjustment. By mid-century both refracting and reflecting elements were combined in the one optic, known as the catadioptric system, but in practice the shorter term continued to be used. By this time, lenticular or refracting lens apparatus had supplanted the simpler reflector type in most of the world's principal lighthouses.
It will be readily appreciated that France was the leading country in the field of lighthouse optics in the early 19th century; particularly was this the case in the fine craftsmanship required for the production of lenticular or dioptric apparatus. In England as early as 1831, the South Shields firm of Isaac Cookson and Company endeavoured quite unsuccessfully to match French quality. The turmoil in France in 1848 drove a number of refugees to seek asylum in England, among whom were Georges Bontemps and an engineer, Tabouret, who had gained an invaluable apprenticeship under the great Fresnel. These two fugitive craftsmen from the continent were engaged by the Birmingham firm of Chance Brothers, a concern which had been commissioned by the government to manufacture dioptric lighthouse apparatus for use on the English and Irish coasts in 1845. As a result, by 1851 Chance Brothers could boast a product on a par with that of their French forerunners and future competitors.6 The English firm enjoyed a monopoly in its field for many years in Britain and its products were exported to all parts of the world. Throughout the 19th century, until the debut and gathering experience of the Dominion Lighthouse Depot in the early years of this century, Chance Brothers supplied a large portion of Canada's requirements.
As early as 1845, the imperial Trinity House had expressed a decided preference for the dioptric type of light. This also was the trend along the American seaboard, where their numbers increased from three in 1851 to no fewer than 310 five years later. Indeed the American authorities announced a programme of total replacement of the old reflector-type lights, whereas as late as the year 1860 there were but 10 dioptric lights in service in the old Province of Canada.7 By this date there was no doubt concerning the superiority of the dioptric or refracting light. Expressed in terms of the percentage of light produced reaching the bridge of a ship, the following figures are significant:
Assuming equivalent oil consumption, the dioptric apparatus emitted a light five times the strength of the catoptric.8 Furthermore, as previously indicated, one light source sufficed with the dioptric system whereas the catoptric required multiple lamps. One cannot do better than to quote a report compiled by a British engineering firm, D. and T. Stevenson, for the Commissioners of Northern Lighthouses, about the year 1850
Dioptric lights were classified according to the internal diameter of the optical apparatus: the largest, lights of the 1st Order, designed for installation in landfall lighthouses, were 72-1/2 inches in diameter. The smallest, lights of the 6th Order used as harbour lights, were less than a foot in diameter. Lights of the 2nd Order were used in coastal lighthouses, to be found frequently at the mouths of large rivers or in the vicinity of dangerous shoals.10
This elaborate construction of precisely ground lenses and prisms has survived to the present, although invariably the light source is now electric. Current electric lamps, because their light source is so concentrated, do not require such complex refracting optical apparatus as their predecessors. Nonetheless, dioptric apparatus of the type depicted in Figure 4 has continued to be used with an electric light source at major lighthouses. As this apparatus is replaced over the course of time, much simpler and less costly optical apparatus will be used with comparable effectiveness.
The Coal-oil Lamp
Until the 1850s in British North America, lighting apparatus was based on the Argand burner with its reservoir of sperm oil, with variants of porpoise or fish oils in maritime regions. At going rates in 1861 of $1.69 to $1.85 per gallon, the traditional sperm oil was expensive and likely to become more so due to the diminishing supply. Already by the early sixties far-ranging whaling fleets operating in the southern seas had depleted the whales. The British and French lighthouse services had in large measure turned to the use of vegetable oils such as colza and rape seed, which was at once cheaper and more readily available. In 1860 John Page, in his report to the Commissioner of Public Works, observed that Canadian experience confirmed the superiority of colza to sperm oil. Although a larger quantity of the vegetable oil was required to produce an equivalent effect, the cost was little more than half that of the traditional material. Despite the fact that lighthouses in the British and French service had converted with few exceptions to the use of colza oil (the source for which was France and Holland), at the time lighthouses both in the Province of Canada and in the United States were still largely dependent on sperm oil.11
A highly significant Canadian contribution to both the lighthouse service and to domestic lighting in general was the distillation in 1846 of kerosene from coal devised by Dr. Abraham Gesner, a physician from Cornwallis, Nova Scotia. Although having taken a medical degree in London in 1827, Gesner later forsook medicine for geology, in which field he made a major contribution to the development of lighthouse illuminants.12 Popularly known as "coal oil," kerosene was first tried in the early sixties in lighthouses on the upper St. Lawrence between Beauharnois and Kingston. According to Superintendent D. C. Smith, coal oil "afforded much better and more brilliant light than the sperm oil."13 At a cost of a mere 65 cents per gallon, coal oil offered the strong inducement of economy. In 1864, Smith recommended the total conversion of all lights in his agency to coal oil, and received the chief engineer's sanction the following year. Mariners plying the upper St. Lawrence reported enthusiastically on the effectiveness of the new kerosene lights.14 Although there was no doubt but that coal oil produced both a brighter and steadier flame with catoptric apparatus, John Page cautioned against its use with dioptric apparatus which was gaining favour for the more powerful lights. Coal oil used in the concentric ring burners required to produce "the large, uniform shape and density of flame required for lights of this class" would have insufficient combustion to be effective.15 But for reflector or catoptric lights coal oil provided at once a much cheaper and more effective illuminant. Until late in the century, this older-style apparatus was still favoured in Canada. In 1861 coal oil was introduced with excellent results at the Father Point lighthouse on the lower St. Lawrence.
Until the advent of petroleum vapour and acetylene lamps early in the 20th century, the circular-wick burner using colza oil and the flat-wick lamp using kerosene held sway in the Canadian lighthouse service. Figure 7 illustrates flatwick coal-oil lamps, so favoured for use with the more numerous catoptric lights until the end of the century. The mammoth burners were fitted with 18- and 24-inch reflectors; their kerosene consumption ran at about double the rate of the smaller models. These kerosene lighthouse lamps, some of which were still in service until post-war years, remind one of the domestic coal-oil lamps which were so much a part of rural households in our grandparents' generation. In the main, these two basic lamp types, fitted with more elaborate refracting and reflecting elements, saw the Canadian lighthouse service through into the early years of the present century.
The Gas Mantle
Around the turn of the century an ingenious device utilizing a familiar illuminant was introduced to lighting technology and survived at some locations well into the post-war period. The incandescent oil vapour light was first installed at L'Ile Penfret lighthouse in France in 1898. The novel principle, trebling the power of all former wick lamps, consisted of the burning of vaporized coal oil within an incandescent mantle. In England Arthur Kitson perfected a lamp on this principle which became well-known as the "Kitson burner," and by 1902 this equipment was widely adopted in the British lighthouse service. In 1921 David Hood introduced an improved mantle of viscous silk doubling the brilliance of mantles up to that time.16 By 1904 petroleum vapour lights had captured the attention of the Canadian authorities, not surprisingly. inasmuch as a 345 per cent increase in candle power was claimed for the oil vapour lights compared with the flat-wick lamp. The new lights came in four sizes ranging from 25 to 85 millimeters.17 Although the well-established English firm of Chance Brothers was credited with producing the best quality petroleum vapour lights at the time, an early Canadian competitor in the field was the Diamond Heating and Lighting Company of Montreal.18 As early as 1909 a 1st Order dioptric apparatus at the Heath Point lighthouse, Anticosti Island, produced a brilliant light of one-half million candlepower.19
A concurrent development of the early 20th century and one to find increasing favour with unwatched lights was that of the acetylene light. First tried in Canada in the Father Point lighthouse in 1902, the acetylene light was reported on favourably by mariners. It was claimed that the range of this reflector-type light was increased from 14 to 28 miles as a result of the conversion.20 In 1903 the department decided to convert all the kerosene lights on the upper St. Lawrence to acetylene and tests conducted that same year demonstrated a five-fold increase in candlepower over the former kerosene flat-wick lamps.21 On the whole, the acetylene light was more applicable to use in buoys than in lighthouses. The advantage of acetylene was that it could be left untended for a period of time, a factor which became significant in the lighthouse service at a much later date. An untended kerosene device, the Wigham lamp, which could be left to its own devices for up to a month at a time, was manufactured in Dublin. The principle of this lamp, which found favour on the Pacific coast, was that of a horizontally burning wick fed slowly over a roller, the burner surrounded by a combustion cone and fitted with lenticular optical apparatus.22 Although both petroleum vapour and acetylene were to be eventually supplanted by electricity, both were in service at scattered locations in very recent years.
Revolving Lights and Colour Characteristics
Until late in the 18th century, all lighthouses exhibited fixed white lights. The first revolving light to sweep the horizon with its beam was tested at Carlston, Sweden, in 1781. By 1790 revolving lights had been widely adopted in the French and British services. Weight-driven clockwork, on the same principle as that used in grandfather clocks, provided rotary power until the advent of the electric motor. The early revolving lights were restricted in size because of frictional losses produced by the light's rollers in the raceway; friction was overcome by 1890, with the introduction of the mercury float mechanism, removing at one stroke the principal restriction on the size and weight of the intricately designed apparatus. The first such light in Canada was installed at Southwest Point, Anticosti Island in 1831. Its beam completed a revolution 100 feet above high water every minute.23
Figure 9 illustrates the two systems of rotary gearing in common use about the middle of the last century. The French system employed offset gearing, and the Scottish, central. Greater stability and smoother operation was claimed for the latter, conditions which were very important with apparatus of great weight.24
Although it was early known that white light was visible at a greater range than coloured, the desirability of colour characteristics in the interests of readier identification was admitted. To an English customs agent, Benjamin Milne, goes the credit for devising the first colour characteristics in lighthouse optics. Produced by 21 parabolic reflectors mounted on a three-sided frame, the whole rotated by means of a vertically mounted axle. The reflectors on one of the three sides were covered with red glass, producing a red beam periodically followed by white. This apparatus was installed in the Flamborough Head lighthouse on the Yorkshire coast in 1806. Light colours now used internationally are white, red and green. White is preferred because of its range, which exceeds that of red or green.
The trend in the early years of the 20th century was the replacement of catoptric by dioptric apparatus, increased power in lights generally, and the replacement of fixed with flashing and occulting lights in the interests of easier identification. The flashing light displays its beam for a briefer span than the subsequent period of darkness, or eclipse; the reverse is the case with the occulting light. In order to render identification yet more certain, combinations of flashing and occulting sequences, sometimes with the additional feature of a colour phase, were devised for different locations. Below are shown the characteristics of lights that are exhibited internationally,
Electricity for lighthouse purposes was tried first at South Foreland, England, as early as 1858. The first electric light in regular service was at the Dungeness lighthouse on the coast of Kent in 1862. The results cannot have been encouraging, for both prototypes were subsequently replaced with the reliable mineral oil lights. The practical adaptation of electricity to lighthouse use was contingent upon two developments; inexpensive transmission of electrical power (or self-contained generating equipment) and the tungsten filament lamp or bulb, the forerunners of which were too short-lived to be practical. In Canada, hydroelectric power became readily available for domestic and industrial use during the first decade of the 20th century and tungsten filament lamps were on the market by 1907. Reed Point, New Brunswick, was the first lighthouse in Canada exhibiting an electric light (1895), but the first electrically operated light and fog alarm was established at Cape Croker, Georgian Bay, in July 1902. The Ottawa firm of A. Trudeau furnished the generating plant.26
Electrification continued apace in the inter-war years, and was completed following World War II. The Commissioner of Lights for the season 1914-15 listed a total of 23 electrically equipped lighthouses of which 8 were in Nova Scotia, 6 in British Columbia and 5 in Ontario.27
By 1931, electricity supplied both light and rotary power in an increasing number of lighthouses. Known as "multi-flashing apparatus" this equipment was first given a trial in 1930 at Musquash, New Brunswick, and at Cranberry Island and Guion Island, Nova Scotia.28 And so compact electric motors came to replace the clockwork and weight mechanisms of yesteryear. Experimental work at the Prescott depot delved into the use of cellophane to impart colour characteristics, safety devices for the protection of optics and, most significant for the future, the now widely used mercury vapour lamp. The advantage of the latter, which is now recently replacing the filament lamp, is greatly extended life, running to many thousands of hours. Electrification of Canadian lights was completed following the Second World War, although the acetylene or oil light has survived in some locations.
Of equal significance in the evolution of the modern lighthouse service at home and abroad was the introduction of the automatic, or untended light. Gustaf Dalen (1889-1937) of Sweden, a brilliant engineer tragically blinded in an accident early in his career, invented the first automatic beacon lighting using acetylene, an innovation which won him a Nobel Prize in 1912. He is also credited with the invention of the first sun valve, a photometric device activated by light, switching the light off once dawn had broken and on with gathering dusk. With the passing of the years more and more lights could be left untended. The advantage of automation, particularly with the introduction of the automatic lamp changer, was particularly obvious for lights in remote locations in the north. Today in Canada the function of the traditional lighthouse keeper is being rapidly phased out in his stead is the itinerant technician making his rounds at periodic intervals by motor, supply ship or helicopter.
The principal post-war developments in the more than two-century evolution of the Canadian lighthouse were the completion of the electrification programme, introduction of radar aids to the lighthouse service (for example radar reflectors), and the conversion of a great many lighthouses to automatic and untended operation.
The completion of electrification in the post-war years was made possible by the extension of hydro-electric power to regions hitherto without it, and of yet greater significance, by the widespread introduction of diesel generating units. By this means the convenience and efficiency of electricity was introduced to the high Arctic. As early as 1948, 481 of 2,469 lighthouses and navigational lights had been electrified. At time of writing (1970) virtually all lighthouses throughout the country have been converted to electricity, as well as a good many buoys.29
Hand in hand with the electrification of lighthouses previously equipped with acetylene or oil vapour apparatus went the development of new high-intensity electric lights. Many of these were installed in the original dioptric lens and prism apparatus; but with the much greater concentration of electric light, very much simpler optics of moulded glass and plastic served equally well at a fraction of the cost. In its report for 1951, the department observed that "major high intensity electric units established for trial service have been favourably reported."30 The superiority of the new mercury vapour bulb over the incandescent lamp was obvious by 1961, the advantage being a light of higher intensity and much longer life; these much smaller bulbs lasted for two or three years, an important consideration with the trend toward unwatched lights.31
A new, lightweight, anti-corrosive aluminum alloy lantern was introduced in 1955. These gradually will replace the heavy cast-iron types with anticipated lower maintenance costs.32 The xenon light developed in Britain and Germany, one of which was installed at Prince Shoal in 1964, produced a light of such unprecedented intensity (32 million candlepower) that it is used only in thick fog.
Electronically operated remote control systems, developed jointly by the National Research Council and the Department of Transport, were designed to operate both lights and fog alarms. The offshore Pelee Passage lighthouse in Lake Erie was the first light station so equipped. The significance of automatic remote control for light stations in remote locations in the far north was obvious. A microwave control system was introduced at the Holland Rock fog alarm near Prince Rupert in 1961.33
Conversion to electricity was more than two-thirds completed by 1961; of the 3,054 lights in service (including buoys), 2,518 were in automatic operation.34
From earliest times various devices had been used at light stations to sound fog warnings in thick weather, Bells, gongs and cannon were all tried at various times and places with varying effectiveness. It was well known that sound transmission over water was subject to peculiar and capricious vagaries, a signal sometimes becoming inaudible close inshore while easily heard farther out to sea. Fog signals due to deflection or echo often gave false bearings. Such difficulties have yet to be resolved completely.
The first steam fog whistle in British North America was installed in 1860 at the Partridge Island lighthouse in Saint John Harbour. Mariners were enthusiastic over the installation, consisting of an 8-horsepower engine producing a pressure of 100 pounds per square inch and costing £350 local currency. Its range in calm weather was established at 10 miles. The whistle was controlled by clockwork, sounding 10 seconds in each minute.35
In 1899, a fog siren was introduced at Belle Isle halfway between the upper and lower lights at a cost of $20,112.64. Power to drive the air compressor was derived from a waterwheel. The signal was produced by a double siren driven by compressed air; the siren was located 250 feet above high water, and the air compressor in a power house at the landing stage. The equipment was English-made36 and, along with a somewhat similar device known as a "Scotch siren" also of British make and in use at Louisbourg and Father Point, gave the best results before the appearance of the diaphone, the product of a Canadian inventor.
In 1902, J. P. Northey, a Toronto manufacturer, developed the diaphone, a major improvement in fog alarm equipment and one still in widespread use today. Basically a modification of the Scotch siren and operating on the principle of a high-velocity pulsating piston rather than a rotating drum, Northey's diaphone produced a blast of more constant pitch for about one-eighth the power expended by the Scotch siren.37 By 1904, diaphones had replaced the older fog alarm equipment at most of the important light stations.
The new diaphone equipment required skilled attendants known as "fog alarm engineers" at major light stations. This attendant shared the keeper's meagre salary. Some lightkeepers, more versatile than their fellows, qualified as fog alarm engineers and so could dispense with assistance. The larger diaphones were fitted with steam-driven air compressors, but the smaller installations were petrol operated.38
The diaphone continued in use throughout the country, notwithstanding the introduction of electronic aids. In 1952, engineers developed a new resonator which greatly increased the audible range. In the mid-sixties Canada once again contributed to fog alarm development with the "Airchine." The Airchine was not designed to replace the diaphone, the largest of which were unsurpassed in range. The Airchine did, however, offer the signal advantage of economy with a signal of almost comparable range. Its air compressors were driven by small electric motors, the whole plant being about one-fifth the dimensions of the standard diaphone. The first Airchine went into service in 1965.39
The electronic fog alarm, a curiously shaped structure (see Fig. 14) of English manufacture, must be considered a major departure in the more than a century's progress in this field. This Stone Chance apparatus has been reported highly satisfactory in the Canadian service.
Submarine Signaling Apparatus
Submarine signaling apparatus, an invention of A.J. Mundy of Boston and Professor Elisha Gray, was another fog alarm system introduced at major light stations early in the century. It was based on an underwater bell connected by cable with the lighthouse; when sounded in foggy weather, the resultant underwater signal was picked up by a direction-finding receiver installed in a vessel's bow. The range of submarine signals varied between 5 and 12 miles.40 The equipment had its limitations, among which was that very few ships were fitted with direction-finders the Tunisian and Ionian of the Allan Line, and the Mount Temple and Lake Manitoba, early transatlantic CPR vessels. Nonetheless, this equipment was installed at 21 lighthouses under contract to the Submarine Signal Company of Boston.41 Submarine signaling was quickly displaced by radio in the early twenties.
Twentieth-century progress in communications was nowhere more apparent than in the fields of radio and aviation, the first of which had an early contribution to make to the lighthouse service in Canada and throughout the world. The first wireless coast station designed for ship-to-shore communications was established at Spezia, Italy, in the summer of 1897. The Lake Champlain, launched in 1900 and initially operated by the Beaver Line, was the first passenger liner equipped with radio. Although Department of Marine wireless coast stations were often separate establishments, some lighthouses, particularly in the early days, combined the functions of light station and radio coast station. In 1904, for example, wireless facilities were installed at the Fame Point, Belle Isle, Cape Ray, Cape Race, Heath Point and Point Amour lighthouses. By 1915, no fewer than 21 lighthouses below Quebec were radio equipped. In the same region, Crane Island, Money Point, Point Lepreau and Partridge Island had telephone facilities.42 By these means, a closer check was kept on ship movements.
Note has already been made of the eccentricities, under certain geographic or climatic conditions, of the familiar bellow and grunt of the fog alarm. The radio beacon installed at a number of radio coast stations and some lighthouses used in conjunction with loop direction-finding apparatus aboard ship was to prove a surer guide to the navigator than the audio signal from diaphone or siren. Cross bearings, however, were themselves subject, under certain conditions, to coastal refraction and hence dangerously misleading. In any case, radio bearings were considered less reliable than visual bearings on a light.
In 1923, the Lighthouse Board recommended the installation of radio transmitter beacons at either the Cape Bauld or Belle Isle light stations, and at Heath Point, Anticosti Island. These experimental radio beacons had a range of about 50 miles. Initially this equipment was to be the responsibility of the lightkeeper.43 The first radio beacon on the Great Lakes was installed at the Southeast Shoal lighthouse in 1927, transmitting a signal every 2-1/2 minutes on a wave-length of 1,000 meters.44
By 1929, radio direction-finding equipment had definitely supplanted submarine signaling apparatus. It should not be overlooked that at this date there were 153 diaphone fog alarms in service, some of which had been operating since 1908. Indeed the fog alarm, as a glance at the latest list will confirm, has been far from displaced; despite the proliferation of electronic aids, mariners still appreciate the discordant blast of the fog horn.45 In 1929 more powerful radio beacons of 200-watt output became available; this equipment was installed at, or near, the Cape Whittle, West Point Anticosti, and the Pointe-des-Monts lighthouses in the Gulf of St. Lawrence. On the Great Lakes (never behind-hand) similar equipment was supplied to the Main Duck Island (Lake Ontario), Long Point and the Southeast Shoal (Lake Erie), Cove Island (Lake Huron), and the Michipicoten (Lake Superior) lighthouses.46 The words of the Liverpool Journal of Commerce are as applicable to the Canadian as to the British lighthouse service.
This speculation, dating from 1929, has yet to be fulfilled.