Elton, Julia; (2025) Reflected Glory: From coal fires to parabolic reflectors: the development of an effective lighting system by the British Lighthouse Service in the 18th and early 19th centuries. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

This thesis examines the development of lighthouse illumination systems in Britain and France during the 18th and early 19th centuries. It has always been supposed that when Fresnel invented the stepped refracting lens in 1819 it shortly replaced all previous forms of lighting. Instead, this thesis argues, the dominant lighting system was the combination of silvered-copper parabolic reflectors and Argand lamps, named catoptric lights, which revolutionized lighthouse illumination and became a reliable and well-tried technology. It lasted well into the 20th century. The essential element of the system was the parabolic reflector first used on the Mersey near Liverpool in 1763. It produced a parallel beam which could be seen far out at sea and represented a major advantage over the uncertain light of coal fires which were subject to the vagaries of the weather. It took time for this property to be understood by the lighthouse authorities but in 1783 the French engineer, Teulère, came up with a design combining a parabolic reflector with a uniform silvered reflecting surface, instead of the mosaic of mirror glass which lined the earlier reflectors, with the newly-invented smokeless Argand lamp. This replaced traditional oil lamps which smoked heavily and quickly sooted up the reflecting surface, rendering it ineffective. Furthermore, Teulère envisaged the use of a turning mechanism to make the signal identifiable. Revolving catoptric lights were then introduced to Trinity House and in 1790 they were used for the first time at Cordouan in France and at St. Agnes, Scilly Isles, in England. Catoptric lights were never liked in France, largely owing to problems with manufacturing the reflectors, which eventually caused the wholesale adoption of Fresnel lenses there by government decree. England had a long-established manufacturing industry and was particularly skilled in the processing and rolling of metals. Catoptric lighting was therefore widely adopted throughout the British Isles. By 1908 175 lights out of a total of 276 were using catoptric lighting and as late as 1965 catoptric lighting was installed at Kish Bank Lighthouse off the Dublin coast. This thesis traces the origins and development of catoptric lighting via a series of dead ends in England and France before the mature system evolved in France. Once it took off after 1790 a small group of specialist contractors and manufacturers emerged in Britain, building up an industry that was able to fulfil the needs of the lighthouse service. Their role is examined to provide a fully-rounded account of this technology. While the civil engineering of lighthouses has been studied in depth, as have the lives of keepers and their families, little of any significance has been published on lighting, the reason such buildings exist. Considering the economic importance of safe navigation, it is surprising that more has not been done, even if the archives of Trinity House only became fully available in the 1990s.

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