SUBMARINE FOG SIGNALS.

Dominion, Volume 2, Issue 456, 15 March 1909, Page 5

SUBMARINE FOG SIGNALS.

4 COASTAL INSTALLATION. inv TEi.Euturu—neess association—eorTitinm) London, March 12. ' Trinity House (tho institution which has charge of various naval matters, including erecting light-houses, etc.), is introducing submarine fog signals. Bells will bo put in position in several places on tho coast, and will bo heard for a distance of 15 miles. • * THE INVENTION AND ITS ECONOMIC VALUE. Several modem liners, such as the Pericles, are equipped with submarine signalling apparatus. Ships not fitted with the apparatus can hear tho submarino boll much farther and with greater certainty than tho present aerial fog signals used by light-vessels, although such ships aro unablo to get direction from them. On the other hand, ships fitted with receiving apparatus would—given a complete coastal installation of submarine bells—bo able to navigate in fog with almu.ii: as great certainty as in clear weather. This statement is made on the authority of< tin official report to the Admiralty, which recommends that light-vessels found the British coast bo fitted with submarine bells. The economic valuo of tho invention is thus, forcibly expressed by the report:—"Tho saving of tiiuo and money, brought about by enabling ships to reach nort, instead of being delayed by fog and losing tides, ctc., would be very considerable, and shipwreck and loss of life would bo rendered less frequent. Men-of-war would be as much benefited by tho submarine boll as merchant vessels, as it is of the greatest importance that they should bo able io navigato the coasts with speed and certainty in thick weather. The bell could also bo used to enable them, when collecting at a rendezvous in thick weather, to determine tho direction of the flagship from a distance of about 10 miles, but this would necessitate fitting selected ships in tho fleets with bells." IVith the' ordinary sound signalling, it is difficult, and often impossible, to locate the sound. AVith submarino signalling sound can be heard up to 15 miles, and, in addition, tho exact bearing and direction of tho sound can bo ascertained. The invention is based, firstly, on the fact that sound is transmitted through water at tho rato of ■1000 ft. per second, as against IlOOl't. in the atmosphere. In addition, tho distributing factors of water are not nearly so great. The sounding bell has an enormous thickness of lip, and it has a peculiarly high note. It is worked either bv electricity, or compressed,air, or by tho ordinary motion of tho waves. The receiver, however, is considered the ingenious part of tho contriv- ' mice. Tho great difficulty to be overcome is tho ordinary noise of tlio ship's machinery. One of tlio conditions required for tho transmission of sound through water, and securing its record, is to have a lank in (he ship containing a liquid heavier than water. By knowing the direction of tlio ship's head, the direction of danger cau bo ascertained within a point or two.