The station, however, was revived upon the old site in 1785, but it had to be abandoned, because it was found to be built at too high an elevation. It was so often enveloped in fog as to be useless, or at least unreliable, to the seafarer. A new tower, accordingly, was erected at a lower level, and brought into service in 1840, the warning rays being thrown from a height of 134 feet above the water. Oil was used with a burner of six rings, the light being officially known as a “fixed oil light of the first class,” while the beam was diffused over an arc of 240 degrees. In the middle eighties the Brethren of Trinity House decided to bring it up to date, and selected electricity as the illuminant, at the same time changing the light from the fixed to the revolving class, with a five-second flash once every thirty seconds. [Illustration: _By permission of Messrs. Siemens Bros. & Co., Ltd._ THE HELIGOLAND LIGHTHOUSE. One of the most powerful electric beacons in the world. Its maximum candle-power is 43,000,000.] The installation is not widely dissimilar from that used at the Isle of May. It comprises two De Meriten dynamos in duplicate, while the lamps are of the modified Serrin-Berjot type, using carbons, not of circular section, but with fluted sides. This shape was introduced by Sir James Douglass, who contended that the former type did not produce the requisite candle-like steadiness of the flame so essential to lighthouse illumination. The dioptric apparatus was of the sixteen panel type, so that the rays were thrown out in sixteen brilliantly white horizontal spokes. To one approaching the lighthouse at night-time, the effect in the sky was somewhat curious. It recalled a huge and illuminated cart wheel or Catherine wheel, lying flat on its side, throwing its rays to all points of the compass in a steadily moving circle. This practice had been borrowed from the French, who went so far as to introduce a twenty-four panel system, and, as in France, the St. Catherine’s light, when first brought into service, was not a complete success. The French considered that, by distributing the light through as many panels as possible, the question of bringing the flashes into action at short intervals would be facilitated, ignoring the fact that by so doing the intensity of each ray was impoverished. In other words, with the twenty-four panel light each panel only received and threw out one-twenty-fourth part of the volume of light emitted by the arc. Similarly, in the St. Catherine’s light only one-sixteenth part of the light produced was thrown through each panel. A few years ago the optical system was replaced by an apparatus having fewer panels. The light thrown from the Isle of Wight pharos, with its beam exceeding 5,000,000 candle-power, represents a marked advance upon the oil light which it displaced, and certainly it ranks as the most brilliant light in the English Channel.