In a previous chapter I have mentioned that, although oil is the most popular form of illuminant in lighthouse engineering, electricity is maintained to be preferable, but labours under one heavy disadvantage which militates against its more general adoption. It is expensive to install and to maintain. Under these circumstances the system has been restricted to lights of the most important character, preferably landfalls or beacons indicating the entrance to a harbour. Thus, we have the Lizard at the entrance to the English Channel; St. Catherine’s on the Isle of Wight; the Rothersand at the entrance to the Weser; the Heligoland flaring over the island of that name; the Isle of May at the entrance to the Firth of Forth; Cape Héve near Havre; and the Navesink light on the highlands of the New Jersey coast, to guide the mariner into New York harbour. The first attempt to apply electricity to lighthouse illumination was made in the year 1859, by the Trinity Brethren, on the strong recommendations of Professor Faraday, who was then scientific adviser to the British lighthouse authorities. The South Foreland light was selected for the experiments, and the magneto-electric machine invented by Professor Holmes, who subsequently perfected the siren, was used. The installation was built with extreme care, as the imperative necessity of reliability, owing to the peculiar nature of the application, was recognized very fully. The large wheels made eighty-five revolutions per minute, and at this speed produced a very steady light. On a clear night, owing to the elevation of the cliff the light was visible for over twenty-seven miles, and could be descried readily from the upper galleries of the lighthouses on the opposite French shore. In order to determine the relative value of electric lighting in comparison with the other methods of illumination then in vogue, another light emitted by an oil-lamp, with reflectors characteristic of the period, was burned simultaneously from a point below the top light, so that passing mariners were able to compare the two systems of illumination under identical conditions. The French lighthouse authorities were not dilatory in adopting the new idea, and electricity was installed in the Cape Héve lighthouse in 1863. The light was brilliant for those times, being approximately of 60,000 candle-power. The French investigators then embarked upon an elaborate series of experiments, and in 1881 an electric light of about 1,270,000 candle-power was established at the Planier lighthouse, near Marseilles. The investigations culminated in the great achievement of M. Bourdelles, who, while engineer-in-chief of the Service des Phares, designed a new electric installation for the Cape Héve light, of 25,000,000 candle-power.