H14: Wood

Q: How was wood used for aids to navigation?

There are few definite instances of lighthouses being fed by wood fires, although they would have no doubt been used in crude beacons on headlands, say. Coal has always been the obvious fuel to use because it burns more efficiently. A wood fire requires much more fuel, is very labour-intensive and much harder to control the light output.

The following is reproduced from the sources indicated.

Compared with a massive masonry tower any iron structure whether open or plated was light and had to depend on the rigidity of the joints for its stability. This was difficult to achieve, especially in a construction of socketed hollow columns, and impossible where basal flanges bolted to the rock were subjected to the action of salt water and abrasion. The fact that wooden piles were often preferred to cast-iron is a clear indication that early builders were aware of its vulnerability to the impact of a storm tossed spar or boulder, yet their fears are hardly vindicated by the survival of countless Victorian pleasure piers with their exotic pavilions. [Hague, 1974, p104]

A handsome building only recently demolished was the high light at Bideford. This, designed by Joseph Nelson, was clearly inspired by the method of bracing used in wooden windmill construction, and also very probably by the triangular construction used by Robert Stevenson as a barrack during the building of the Bell Rock. Nelson was also responsible for the wooden Burnham low light which like the famous Smalls was a piled structure supporting an enclosed cabin and lantern. [Hague, 1974, p103]

For obvious reasons not many old wooden lighthouses have survived, although wood was used extensively in the seventeenth and eighteenth centuries. Examples were Harwich, Winterton, Dungeness and many others of which there are records of their destruction by fire. [Hague, 1974, p103]

After some alterations of the Cordouan wood fire, the mariners complained that they could not see the light at the distance of two leagues as formerly. But Smeaton informs us, that the coal fire of the Spurn Point Lighthouse, at the month of the Humber, which was constructed on a good principle for burning, had been seen thirty miles off. [Findlay, 1862, Ch. III]

Bellows were used with great effect to provide a focused draught of air used to improve the combustion of a coal or wood fire.

The material used as a fuel to produce the light is an illuminant. Examples of illuminants are candles, coal, torches and pitch fires, wood, oil, kerosene (paraffin), gas, electricity.

1284 Two wooden lighthouses, known as vierboeters, were built at the entrance to Nieuport in Flanders, confirmed in a charter of 1366, as well as others at Dunkirk, Ostend, and Blankenberg. In 1388 one of the two remained on the mole at Nieuport, and another stone lighthouse was built there in 1414. Each was of stone with a pointed slate roof similar to the old lighthouse at St. Catherine's. The smaller lighthouse (kleine vierboete) was damaged by gunfire in 1795 and disappeared. The larger (groote vierboete) was rebuilt in 1858 and was used as a lighthouse from 1863 to 1883. It was still in existence in World War I, but nothing remains today. [Hague, 1975, p22]

1700 Fifteen major navigational lights exist in Britain, of which 12 are coal fires. Of the five main lighthouses on the French Atlantic coast, one burned wood and one burned oil. In Sweden, four out of the five existing lights burned coal. [Stevenson, 1959, p273]

1717 The burning of a wood fire nightly since 1612 gradually injured the stonework at Cordouan lighthouse to such an extent that the upper part of the tower had to be removed in 1717 and rebuilt with the grate set at a lower level. At the same time coals displaced wood as the fuel. But navigators objected to the change, as lowering the grate reduced the geographical range of the fire. They remained dissatisfied until 1727 when an iron lantern was put up over the grate which protected the fire from the weather and resulted in a brighter and steadier blaze. Another real benefit came from the lantern's thin vertical bars which offered less obstruction to the light than did the former masonry pillars. In addition, polished metal sheets in the form of an inverted cone were placed above the grate with the object of reflecting the glow of the fire, but they proved useless for that purpose as their newly-cleaned surfaces always became covered with soot shortly after lighting the fire. [Stevenson, 1959, p46]

1727 Wood ceased to be used as an illuminant at Cordouan. [Stevenson, 1959, p271]

1760 21 out of the 25 major navigational lights in Britain use coal, excluding Eddystone and two lightships which, by their nature, must use candles or oil lights. Of the six French lighthouse, four burned coal and one wood or coal. In Sweden, four out of six lighthouses burn coal. [Stevenson, 1959, p273]

1782 Wood ceases to be used as an illuminant at Chassiron. [Stevenson, 1959, p271]

1831 An early form of wooden lighthouse can be seen in a sketch made in the Isle of Man in 1831. This structure of rough wood planks resembles a dog kennel supported on a massive single post and entered through a small trap door in the side reached by a heavy wooden ladder. Presumably the light was shown through a window in the side opposite the door. [Hague, 1974, p103]

1839 The reason that the lower of a pair of lights was often of wooden construction is that such a structure was expendable or easily moved should the channel shift, or alter in any way. Indeed, some lower leading lights were designed to be movable such as the timber framework structures at Drogheda of 1839 which could be pushed along on timber rails. These were later replaced by steel structures, and at the same time similar towers were erected at Scattery Island; but these were movable in order to avoid destruction during Army firing practice. They were blown down soon after erection, but those at Drogheda still function. [Hague, 1974, p103]

1855 One of the last recorded uses of wood as an illuminant occurred at Kamchatka. They were replaced by oil lights. Stevenson, 1959, p2711760 21 out of the 25 major navigational lights in Britain use coal, excluding Eddystone and two lightships which, by their nature, must use candles or oil lights. Of the six French lighthouse, four burned coal and one wood or coal. In Sweden, four out of six lighthouses burn coal. [Stevenson, 1959, p273]

1782 Wood ceases to be used as an illuminant at Chassiron. [Stevenson, 1959, p271]

1831 An early form of wooden lighthouse can be seen in a sketch made in the Isle of Man in 1831. This structure of rough wood planks resembles a dog kennel supported on a massive single post and entered through a small trap door in the side reached by a heavy wooden ladder. Presumably the light was shown through a window in the side opposite the door. [Hague, 1974, p103]

1839 The reason that the lower of a pair of lights was often of wooden construction is that such a structure was expendable or easily moved should the channel shift, or alter in any way. Indeed, some lower leading lights were designed to be movable such as the timber framework structures at Drogheda of 1839 which could be pushed along on timber rails. These were later replaced by steel structures, and at the same time similar towers were erected at Scattery Island; but these were movable in order to avoid destruction during Army firing practice. They were blown down soon after erection, but those at Drogheda still function. [Hague, 1974, p103]

1855 One of the last recorded uses of wood as an illuminant occurred at Kamchatka. They were replaced by oil lights. [Stevenson, 1959, p271]