ILLUMINATING LIGHTHOUSES

Gisborne Times, Volume XXV, Issue 2174, 2 September 1907, Page 1

ILLUMINATING LIGHTHOUSES

SOME INTERESTING FACTS. The question raised _ as to the visibility of the Lizard light in connection with tho wreck of the fiuovic has drawn attention to the problems connected with t-lie relative efficiency and visibility of tho various illuminants used in lighthouse work (writes Tho Times Engineering). Some years ago the subject was investigated by a Royal Commission, but conditions have changed in tho interval. On tho main question of visibility, it is obvious that.tho cas~ is mainly governed by atmospheric conditions ; but it is stated that in foggy weather the

incandescent oil li<dit has a penetrative effect superior to that of the electric arc. There is further to be taken into account the elevation of tho light above the level of the sea, which, of course, is subject to a wellknown law. The condition of the atmosphere is,’however, a vital factor. _ It is well known, too, that tho conditions of the atmosphere, in addition to its influence on range, have an effect upon color. Oil, gas, and electricity are all in rise as lightlionse illuminants. but the employment of the last, for reasons-relating to. cost of installation and expense of upkeep, is:confined to salient headlands. The; great developpipnt during, recent years,"has;been in the application of the incandescent burner to lighthouse work, the system which is now finding most favor with the authorities being the incandescent petroleum vapour burner. The object of the authorities at present is

to obtain tho flashes at very short intervals, and to reduce the. duration of the long dark poriod in proupflashiug lights. A typical example of the modern, lighthouse system is found in the Boncliy Held light. 11l some recent lighthouse installations, notably the Fast-net. and tile Maiden, the apparatus is installed in Inform, so that iu foggy weather two . synchronised lights are used. These lights are placed perpendicularly, but in French practice tho two lights are placed side by side on the same revolving platform, and, although tho object in the case of British lighthouses is to increase tile illuminating, power in foggy weather, it has been noted iu the ease of the electric light that a greater candle-power is obtained -with two arc lamps than with a single one using the same amperage and voltage. Triform and nui.lriform app ira tus is also employed particularly with gas installations, which until a recent period -were I -largely in use on the Irish coast. I These, however, are being gradually I supplanted by the incandescent oil I burner, which, from present indic-i- I t,ions, appears to be tile aparatus of I the -future in connection with light- I house work. I