The Argand Lamp and Early Illumination
Before the Argand
For most of the eighteenth century, the light emitted by a lighthouse was feeble by modern standards and variable by any standard. Coal fires burning in iron grates on open towers had been used for centuries: the lights on Tynemouth Priory, the coal fire maintained by monks at North Shields, were already a recognised navigation aid in medieval times. But a coal fire burns unevenly, can be doused by rain, requires a constant supply of fuel carried to the lantern by hand, and produces as much smoke as light. The first enclosed lanterns at Eddystone and other major stations used candles — dozens of them in circular frames — which were marginally more reliable but still dim.
Tallow candles gave a light of roughly one candela each. The great multi-wick burners used at some early lighthouses might aggregate to fifty or sixty candles of illuminating power. At a lighthouse eight miles at sea, this barely provided enough light to be useful on clear nights and was effectively invisible through mist or rain. The light that mariners depended upon to identify a dangerous headland was sometimes little brighter than a domestic hearth.
Aimé Argand and His Lamp
Aimé Argand was a Swiss physicist and chemist, born in Geneva in 1750, who developed his innovative lamp in the early 1780s while working in England and France. The Argand lamp differed from all previous oil lamps in two essential respects: it used a hollow cylindrical wick rather than a flat or twisted wick, and it enclosed the flame in a glass chimney. The cylindrical wick allowed air to reach the flame from both inside and outside, providing far more oxygen for combustion than any previous design. The glass chimney stabilised the airflow and protected the flame from draughts.
The result was a lamp that burned whale oil or colza oil steadily and produced a bright, stable flame of roughly nine candelas — approximately the equivalent of nine candles — from a single wick, without the sooty, flickering output of earlier designs. By using multiple Argand wicks in a single burner assembly, lighthouse engineers could multiply this output. A burner with nine concentric wicks, such as those supplied to British lighthouses by the manufacturer Matthew Boulton in the 1790s, could produce an aggregate output that represented a genuine advance over anything previously available.
Adoption in Britain
The first British lighthouse to use the Argand lamp was the Stonehaven lighthouse in Scotland, where it was installed in 1787. Trinity House adopted the Argand system for its lighthouses shortly afterward, and by the first decade of the nineteenth century, most major English and Welsh lighthouses had converted from candles or coal to Argand oil burners. The improvement in light output was marked and quickly noted by shipmasters.
The adoption was not without controversy. Argand attempted to patent his invention in France and England and encountered fierce resistance from established manufacturers and distributors of lighting equipment. His English patent was infringed almost immediately, and he spent much of his later career in legal disputes. He died in 1803 without the financial recognition his invention deserved, though his name remained attached to the lamp type throughout the nineteenth century.
Reflectors: Catoptric Systems
The Argand lamp alone did not solve the problem of concentrating lighthouse light into a useful beam. A bare flame radiates equally in all directions; most of that light is wasted on the sea and sky. The solution adopted for the first half of the nineteenth century was the catoptric system — arrays of parabolic mirrors that collected the light from the Argand burner and reflected it forward in a concentrated beam.
The Scottish engineer Thomas Smith designed and manufactured some of the first effective lighthouse reflectors in the 1780s and 1790s, supplying them to the Northern Lighthouse Board. His stepson and successor, Robert Stevenson, refined the design and applied it systematically across the Scottish lighthouse network. The mirrors were fabricated from copper, hammered into a parabolic shape and silver-plated to maximise reflectivity. Each mirror, typically 60 to 70 centimetres in diameter, was positioned with the Argand burner at its focal point, so that the diverging light from the flame was redirected into a roughly parallel beam.
A typical catoptric lighthouse fitted multiple burners and mirrors, arranged in a circular frame that rotated to produce the characteristic flash. Bell Rock lighthouse, when completed in 1811, carried four sets of four mirrors each arranged around a central frame, with alternating red and white glasses in front of alternate sets to produce the station's identifying character. The whole apparatus was rotated by a clockwork mechanism driven by a falling weight, making one revolution every few minutes.
Fresnel and the Dioptric Revolution
The catoptric system had a fundamental limitation: parabolic mirrors, however carefully made, captured only the light that fell upon their face. The light emitted sideways, upward and downward from the Argand burner — the majority of the total output — was lost. Augustin-Jean Fresnel, a French physicist and optical engineer, addressed this problem in the 1820s with a design that used lenses instead of mirrors to capture and redirect the light from all directions.
Fresnel's dioptric lens, first installed experimentally at the Cordouan lighthouse at the mouth of the Gironde in 1823, surrounded the light source with a series of concentric lens elements arranged in zones. The central element was a conventional convex lens that refracted the light directly forward. Above and below it were angled prisms that captured light travelling upward and downward and bent it forward through total internal reflection. The complete assembly, when rotating, sent virtually all the light from the burner into a powerful horizontal beam.
The Fresnel lens was so much more efficient than the catoptric mirror array that its adoption effectively rendered the Argand-and-mirror system obsolete within a generation. But it did so by building upon the Argand lamp: the Fresnel lens required a bright, stable, point-like source at its focal point, and the Argand burner provided exactly that. The two inventions were complementary, and the combination of the Argand lamp in its most developed form — the multiple-wick burner — with a first-order Fresnel lens defined the lighthouse of the high Victorian era.
Oil Types and Their Properties
The choice of oil made a significant difference to the output and reliability of an Argand burner. Sperm whale oil, obtained from the spermaceti organ of the sperm whale, was the preferred illuminant for the finest lighthouses through the first half of the nineteenth century. It burned cleaner and brighter than tallow or vegetable oils and had a higher flash point, making it safer to store and transport. Lighthouse authorities paid a premium for sperm oil and tracked consumption carefully in station records.
As sperm whale populations declined under commercial whaling pressure, colza oil — pressed from the seeds of the plant Brassica napus, the same plant cultivated today for rapeseed oil — became the standard substitute. It burned well in a correctly adjusted Argand burner but required more careful maintenance of the wick and burned with a slightly more yellowish light. Many lighthouses shifted to colza oil in the 1840s and 1850s and continued to use it until mineral oil became widely available from the 1860s onward.
The Multiple-Wick Burner
The most powerful form of the Argand lamp for lighthouse use was the multiple-concentric-wick burner, developed through successive generations of improvement by lighthouse engineers in France, Britain and the United States. By the 1840s, burners with four or five concentric wicks were standard in major lighthouses, producing a flame far brighter than any single-wick Argand. The Fresnel-system apparatus at Cordouan, updated in the 1840s, used a four-wick burner producing a light of roughly five hundred candelas before any lens concentration — an increase by a factor of fifty or more over the candle-lit lighthouses of half a century earlier.
The precise adjustment of a multiple-wick burner was a skilled task requiring daily attention. Each wick had to be trimmed to exactly the right height; the oil reservoir had to be maintained at the correct level to sustain consistent capillary flow; the glass chimney had to be cleaned of the fine soot that inevitably formed. A keeper who allowed a wick to burn too high would char the chimney and reduce the light output; one who trimmed too low reduced the flame. The title 'wickie' — the informal name for a lighthouse keeper — derived directly from this central duty.
From Oil to Petroleum and Beyond
The paraffin oil lamp, introduced to lighthouses from the 1860s onward, used the same Argand principle — hollow wick, glass chimney, parabolic reflector or dioptric lens — but with a more energetic and more volatile fuel. Paraffin burned brighter and more cleanly than colza oil and was cheaper and more easily transported. It required adaptations to the burner and storage arrangements, but these were straightforward, and the transition was swift.
Vaporised paraffin, burned under pressure in a mantle rather than a wick, represented the next step. The Chance Brothers' vaporising burner, introduced in the 1890s, burned paraffin forced through a jet to produce a fine spray that combusted in a Welsbach mantle, giving a white incandescent light several times brighter than a wick flame of the same fuel consumption. This system remained standard in British lighthouses until electric light took over.
Open the map to explore historic lighthouses where original Argand-era optics and fittings have been preserved, and trace the evolution of lighthouse illumination in the towers you can visit.
A Legacy in Precision
The Argand lamp's significance lies not only in the light it produced but in the discipline of precision it imposed on lighthouse engineering. A lamp whose output depended on exact wick height, exact oil level and exact chimney condition trained lighthouse keepers — and the authorities that employed them — to treat illuminating apparatus as precision equipment requiring careful maintenance to specification. That culture of exact care persisted through the paraffin era and the electric era and survives today in the maintenance standards that govern automated LED installations.