Apparently, the weakest point in the installation is the submarine cable, but the engineers entertain no apprehensions on this score. It is too stoutly made and too heavily armoured to rupture very readily. Experience has proved its efficiency and reliability, while a long life is anticipated for it. The Platte Fougère unattended lighthouse has opened up new possibilities for protecting wild coasts. It has proved conclusively that there is no difficulty in maintaining such a station and controlling it from a distance so long as automatic apparatus which has proved its worth is employed. This practical application should serve to solve many peculiar problems. No longer can the bogie of expense be put forward as an argument against safeguarding a notoriously evil length of shoreline or isolated rock, even if the latter is exposed to the heaviest seas known. The Guernsey installation was completed for £8,500, or $42,500, and is as serviceable as the ordinary type of tower, which in this instance would have cost at least £60,000, or $300,000, to build and equip. From the maintenance point of view it is equally convincing and economical, inasmuch as only two keepers are required in the place of the four who otherwise would have been necessary. [Illustration: THE DALÉN “SUN-VALVE,” THE MOST WONDERFUL INVENTION OF MODERN LIGHTHOUSE ENGINEERING. Depending upon the action of daylight alone, it automatically ignites and extinguishes the light at dusk and dawn respectively.] The system which has been devised by Mr. Gustaf Dalén of Stockholm, and which is exploited by the Gas Accumulator Company of the Swedish capital, operates with dissolved acetylene. The first light in Scandinavian waters to be brought into action upon the “Aga” principle, as it is called, was installed in the Gasfeten tower, an exceedingly isolated beacon which offered every means of testing it thoroughly. The idea follows the broad lines of that adopted in connection with lightships, and, the Gasfeten experiments proving completely successful, it has been adopted extensively since, not only by the Swedish authorities for the lighting of lonely waters in the Baltic Sea and Gulf of Bothnia, but by various other Powers. The Straits of Magellan are protected in this way, and when one recalls the sparse population which dwells upon the banks of this short-cut between the Atlantic and Pacific Oceans, and bears in mind the fact that the lights have to be left to their own automatic action for some months on end, then one may realize the perfection and reliability of the invention. The failure of a light in such treacherous waters would be notified speedily to the authorities responsible for the illumination of this sea-lane, but no such complaints appear to have been received from passing vessels. These lonely lights for the most part are of a very simple character, a result due to local conditions. As a rule they are planted on lofty eminences--not at too high an elevation, as thereby