| 
Lighthouse of Alexandria  The Lighthouse of Alexandria, Egypt, one of The Seven Wonders of the Ancient World Speaking of the lighthouse of Alexandria, "the poet Lucan, in his 'Pharsalia,' asserts that it [the Pharos Lighthouse of Alexandria] indicated to Julius Caesar his approach to Egypt on the seventh night after he sailed from Troy; and he makes use of the significant expression 'lampada,' which could hardly be applied, even poetically, to an open fire," wrote W. H. Davenport Adams in his 1871 edition of Lighthouses and Lightships. "Pliny expresses a fear lest its light, which, seen at a distance, had the appearance of flames, should, from its steadiness, be mistaken for a star; but assuredly he would not have spoken in such terms of the wavering, irregular, and fitful light of an ordinary fire. We conclude, therefore, that its lighting apparatus was more complete than has generally been supposed." An animated picture of a simple carbon arc searchlight as the fiery electric mirror may have appeared in antiquity The Pharos light was indeed "more complete than has generally been supposed" because its flashing searchlight was probably fired by arcing carbons like those illustrated above and below. Its light certainly did not come from a common open type of fire, which is totally unexplainable. “Several authorities tell us there was a hearth on the top of the tower,” wrote Jean-Yves Empereur. “But, as someone once said, the closer we get to this fire and to the light it shed, the more we moderns are plunged into the darkness of contradictory hypotheses and errors.” A magazine's picture of the electric carbon arc light, popular in 19th-century lighthouses, street lights, and elsewhere Wood was not the fuel used for the fire because it burns rapidly and a large amount is required to sustain it, which can bring devastating results. “The disappearance of a forest from the island of Anholt,” wrote D. Alan Stevenson, “was said to be due to the insatiable demand for fuel for its lighthouse fire.” However, there was no danger of this ever occurring in Egypt because it hardly had any trees, except for mainly scrubs like acacia and tamarisk. Egypt’s lack of wood, in fact, even prevented it from building even a semblance of a formidable navy in antiquity. Mr. Maurice pointed out: “There was one insuperable objection to their maintaining any considerable navy; I mean the total want of timber proper for its construction and repair, of which the whole country was so entirely destitute, that even the boats on the Nile were obliged to be fabricated either of baked earth glazed and varnished, or of rafts sewed together with the papyrus.” Furthermore, no practical sources of trees existed nearby, which could sustain a continuous yearly blaze on the Pharos Lighthouse. Coal would not have solved the problem. It was hardly known in the Mediterranean area. Naphtha, according to Plutarch, seeped through the ground around Babylon, and was sometimes set afire to impress onlookers with its flaming volatility—but we have no records of any attempts to harness it for ancient lighthouse fires. Pitch, widely used in ancient torches, was also not an appropriate fuel for lighthouse beacons. Under a topic Torches and Pitch Fires, D. Alan Stevenson explained why: "Torches seldom served for seamarks: such small bodies of fire fluctuated too wildly in light value. After several years’ use they were discontinued at Fréhel in France in 1710 as a roof failed to protect them from extinction by rain. So great was the volume of smoke which torches produced that their use within closed lanterns or glass screens was impracticable: soot sullied the inside of the panes and soon blocked the emission of light rays." Unprotected open-air fires blazing away atop the lofty pinnacles of light towers belch out much more smoke than these torches, and their light varies, especially in the wind—an unpredictable weather feature that can rapidly change their character. Lighthouse records show that at times even a small breeze choked out an open fire and caused it to release little light but great volumes of smoke instead, and at other times, a hefty gust of wind whipped up a high, fluctuating blaze. Sometimes, the wind fanned the flames away from the sea so sailors could not see its light, and at other times rain blew in under the roofs of its cupola, and put out the fire completely when seamen needed it most. Beside the wind, the heat from an open fire can collapse a cupola’s stone roof down on the heads of lighthouse attendants, and the fire’s smoke fumes can smother them to death. In 1790, the fumes from a fire on the lighthouse on the Isle of May suffocated the light keeper’s entire family, except one tiny survivor, an infant daughter, whom rescuers fortunately found alive—three days later! Beside these problems, there is always the chance that a ship’s pilot can mistake an open fire on a hill or on a beach for a lighthouse beacon or navigation light. A double dose of this type of mistaken identity occurred some years ago. On the dark night of the 19th of December, 1810, two of Her Majesty’s ships NYMPHE and PALLAS wrecked near Dunbar because their pilots mistook the light of a limekiln on the coast for the navigation light on the Isle of May, off the eastern shore of Scotland. Notwithstanding all these unsolved problems with an open fire blazing away on the Pharos and an appropriate fuel to maintain it, we have one more curious but rejected suggestion. “Dried animal dung could have been a possible solution to the problem and is still widely used in native houses today,” wrote Peter Clayton, “but, once again, the sheer quantity required presents problems.” Furthermore, Emil Ludwig claims, “An open wood or pitch fire would have shone only seven miles.” We assume he was speaking of a clear-weather blaze. A misty atmosphere would substantially shorten the distance. Worse yet, a heavy fog, like the one encompassing the Pigeon Point Lighthouse in the photograph above, makes even an extremely bright electric light also visible at only a very short distance. The Pharos Lighthouse of Alexandria in animated form Speaking of some interesting ancient technology that should solve the problem with type of fiery light on the Pharos, "which has no equal on the face of the earth," the medieval Arab geographer Al Bakri claimed the Alexandrians of ancient Egypt "assigned to its summit the celebrated mirror, which was made from a mixture of remarkable and extraordinary substances; they were able to see by it enemy ships on their way towards Alexandria, several days away, to prepare themselves for defense." Beside the mirror's function as a telescope, which was obviously used also to study the stars, it was used as a heliostat in sunlight; and at its center, the brilliant electric arc-light fire flashed out warnings on cloudy days and at night. “That the Pharos was used as a signal-station as well as a lighthouse is certain,” wrote Dr. A. J. Butler, “and at the time of the Arab conquest it was in full working order and flashed the sun by day and its own fire by night many leagues over the sea.” He went on to claim in his exhaustive work titled The Arab Conquest of Egypt and the Last Thirty Years of Roman Dominion that the Pharos Lighthouse was a “conspicuous landmark visible by day and by night at a distance of sixty or seventy miles.” For much more on ancient telescopes, ancient lighthouses, and ancient electric lighting, see The Electric Mirror on the Pharos Lighthouse and Other Ancient Lighting. This page was last modified on Friday, August 20, 2010 | |