The Wigham petroleum system has proved similarly economical and reliable, and has been installed in some of the wildest corners of the globe. The Congested Districts Board for Ireland have established a number of these beacons on the rugged west coast to assist the fishermen in making their harbours at night. Many are placed in very exposed positions on headlands, where they are frequently swept by the full force of the Atlantic gales. The Austrian Government has adopted the principle for lighting the dangerous coasts of the Adriatic near Trieste, while the shoreline of Jamaica is safeguarded by more than sixteen lights of this type. Many of these lights suffered severely from the effects of the earthquake which overwhelmed the island a few years ago, but others withstood all the shocks successfully. In this instance, had expensive and massive lighthouses of the usual type been erected, the loss would have been considerable, in view of the severity of this seismic disturbance and the widespread destruction which was wrought. These lights play a very prominent part in the guarding of the southern ocean, the Australian shores being protected by over sixty such beacons, many of which are established in very exposed and isolated positions off the mainland. While the day is still far distant when expensive graceful towers, carrying immensely powerful lights, will be no longer constructed, the perfection and utility of the unattended light, in one or other of its many forms, are assisting tangibly in the solution of the problem of lighting busy shorelines adequately and inexpensively. Structures costing tens of thousands sterling in future will be restricted to important places, especially in connection with sea-rocks, such as landfalls, or to those some distance from the land, where a fog-signal station must be maintained, unless the example of the Platte Fougère land-controlled station becomes adopted. CHAPTER XXII FLOATING LIGHTHOUSES Hand in hand with the development of the unattended light for service on land positions has proceeded the adaptation of the floating light. This may be described briefly as an enlarged edition of the lighted buoy, which is such a conspicuous feature of our harbours and estuaries. Yet it is more than a buoy. It can fulfil all the purposes of a light-vessel, both as regards the emission of a ray of light or a distinctive sound, so that both audible and visual warning are given simultaneously. These lights likewise are automatic in their action, and, when set going, require no further attention for some time. Nine months or more are often permitted to pass without human hands touching them, and they have solved some very abstruse problems in connection with coast lighting.