This brass satyr-hoofed tripod, embellished with bacchic-lions and Grecian palm-flowered acroteria, derives from a bronze table pattern, in the manner of a Roman tripod-altar, that was invented around 1800 by the connoisseur Thomas Hope (d.1832) for his Duchess Street Mansion/Museum and illustrated in his house guide, Household Furniture and Interior Decoration, 1807 (reprint, 1970, pl. 19, fig.1). Another of Hope's French-fashioned tripods, also featuring ring-centred ties, was described as folding "after the manner of ancient tripods", and was probably executed by Alexis Decaix (d.1811), the Rupert Street manufacturer of French bronze and ormolu, who was employed both by Hope and George, Prince of Wales, later George IV (Hope, ibid., pl. XVII, no. 5). Hope's pattern would have well suited a sideboard water-cistern in the manner of a French "fontain eau portable".
THE PRESENT MODEL
These formed the oil-cistern for a four-wick mechanical lamp like those designed for the Commissioners of the Northern Lighthouse Board by Robert Stevenson (d.1850). Stevenson served as the sole Engineer to the Commissioners from 1808 to 1842. This "Mechanical Lamp for Dioptric Lights" would have been executed by the Edinburgh founder James Milne and Son, brass founders of Chalmer's Close. In its complete form, this oil cistern would have had a clockwork mechanism underneath the cistern and a wick holder with glass chimney above it.
The heavy oil that formed the lamp's fuel, which could be any form of oil ranging from whale-oil to rapeseed oil (in times before the discovery of paraffin or kerosene), was kept in the slightly tapered copper cistern on a tripod stand with adjustable legs, and kept at a constant pressure by means of a weight floating on the top of the oil. A weight-driven clockwork motor pumped the oil up from the reservoir to each wick, effectively "force-feeding" the oil into the wick, in order to reduce charring, so that the lamp could burn for several hours before needing replacement. The flame from these compound wicks, which were cylindrical in shape, one inside the other, could measure up to 102 mm. in diameter and 140 mm. high. Since they produced such a remarkable amount of light, the lamps also gave of a large amount of heat, so much so that elaborate ventilation systems were necessary to prevent the lantern houses from burning down. The heat produced would also have been enough to endanger the joints of the lamps themselves, so a cooling system was integrated into the mechanism, with three times the actual amount of oil required for burning being pumped up to the wick, so that some oil ran back down into the reservoirs unburned, but cooling the system down as it went. A four burner lamp such as those presented here would have been part of, could burn through over 4500 litres of heavy rapeseed oil per year.
A similar lighthouse lamp is displayed in the Royal Scottish Museum, Edinburgh (D. B. Hague and R. Christie, Lighthouses: their architecture, history and archaeology, Dyfed, 1975, pp. 151-157, fig. 37). One lamp was sold anonymously, Sotheby's, London, 20 February 1987, lot 131 and another was sold anonymously, Christie's, New York, 12 October 1996, lot 171.