Evolution of Lighthouse Fog-Signals

Mr. Daboll designed a trumpet having a metallic reed sounded by compressed air in 1851^[1]. In 1860, it was patented the application of condensed air to the sounding of whistles or horns, with machinery to produce the revolution of the horn whilst sounding^[1]. The lights of the area could be strengthened by condensing system technology^[1].

In 1863, Professor Holmes devised a trumpet, having a reed of German silver sounded by compressed air, with an automatic arrangement whereby the trumpet can be placed at a distance from the air compressor and engines^[1]. In 1874, Professor Tyndall reported to the Trinity House that the siren is the most powerful fog-signal tried in England and is specially powerful when local noises have to be overcome^[1]. However, some have considered, during fog, that light may often become a source of confusion to the mariner; and, in the event of another light being required in the neighbourhood, it becomes a deduction from the means of distinguishing it from the lights which existed previous to its establishment^[1].

There was the development of the automatic meter for producing intermittent lights by the flow of gas^[1]. This meter always passes a sufficient quantity of gas to secure the constant burning of a small jet, and at regular intervals there is an increased supply that goes to the main burner until the action of the meter cuts off the larger supply and the small jet is again left burning alone^[1]. For additional means of recognition, the forces influencing the relative visibility of such distinct colors also came into focus^[1]. The relative stability of these attributes has been of great importance^[1].

There have been identified that, depending on geographical position, towers can be subject to 'almost incessant tremor'^[1], or that the slope of the ledges directs the mass of water obliquely^[1]. Also, if the rock overhangs, owing to the wearing action of the waves, the tower should, if possible, be built at a distance from the place where this dangerous action is in progress^[1]. For these reasons, mass and weight are preferred, as the strength which results is constantly subject to be impaired by the loosening of such fixtures^[1].