SUBMARINE SIGNALS.

Dominion, Volume 2, Issue 544, 26 June 1909, Page 15

SUBMARINE SIGNALS.

. AN INTERESTING ARTICLE, In thia weok'e Gazette appears a most interesting artiolo dealing with suhmarina signals oullod from tha "Juno Pilot Chart," issued by the United States Hydrojraphio Offioo. The article states by way of a preamble that ' Captain L. W f Betms in a latter to thejnanager of the Norfolk and North American Steamship Company, Limited, reports that aithent tha 1 wd of a microphone by simply putting his ear to the sUh of tha vessel in the I fore-peak, ho , heard the snbmann* bells of the Toniruo Lijhtvoasel on his port bow at a distance ef six Jnilos. By putting his ear, close to each side of the ship h* states that on* can dishnjnish whiob side of The ship th,e sound comes from, T*s artiolo goes on to pay .— "Until recent times the sonnd-sienals generflly'nsed wide mariners, especially during fogs, were, with certain modificatioiib, 6irens, trumpets, 6t«am-nhistles, bell-boats, bell-buoys, rockets; gongs, bells strnok by machinerj, and cannons flrod by powder or eun-eotton. In connectioji with aU these implements the atmosphere is the medium of transmission of the ' sounds emitted from tho sounding-apparatus,, but it is a ch&rncteristio of the air that, in contiguous spaces of the atmosphere, tho tomper&ture, humidity, and pressure vary in'such a manner as to produce a etato which bears the same relation to eoujld as oloudiness does to light. s "Tha manner has long since learned to bo exceedingly cautious "about > depending upon aerial 6ound-signals, even when near. Experience has taught hiru that he should not assume that ho is out of hearing distanco of the position of tho' signal-station becauso ho fails to hear ita reund; that he should not assume that because he heara a fog-signal faintly ho is at a' great distance from it, nor that he is near , because he hoars tho sound plainly; that he Bhonld not assume that ho has reached a given point on his course because ho hears the fogsignal at the same intensity that he didMvhen formerly at that point,' neither should he assume that he has not reached this point he--1 caiKe he fails to hear the fog-signal as loudly , as'beforo, or because he does not near it at all; 'and,that'ho should not assume that the fog--1 signal has oeascd sounding because ho fails to hear it. even when within easy earshot. "While both tha range and the certainty of the transmission of sounds through tho air may bo)enhanced by imparting such excessive energy to the 6onnd-wavos as to render them less liablo to tho dissipating influences of a j Variable atmosphere, yet, with tho fog-signals heretofore m us 6, it has been 'impossible to distinguish, by any means available to the mariner at sea, 1 the times when he might expect aberrations m audition from tho times when the sounds'would be heard, normally ~as to force and place. , "Water 19 a less 'mobile medium than air, less reaponstvo to marked variations of density arising through obangos in temperature and pressure, and, therefore, less subject to variations of homogeneity and more reliable as an cgehoy of tho transmission of sound-wa\es - 'Jin. his experiments on Lako Geneva, in 1826, Colladon had a bell, weighing about 1501b., suspended some sft.' under water from the side of a boat, and struck by a hammer to theiend of a lever. Stationed in another boat, he listened for tho bell-sounds propagated beneath [the surface, which were conveyed from .the- water by a cylindrical tube of tin some 9ft foilg and Cm. in diameter. One end of this - tube' terminated in an orifice for insertion in tho oar, and the other was spread out somewhat'in the form or a spoon, with its orifice closed by a flat_ elliptical plate of tin about two. square feet in area. By attaching a suit-able-weight to thevlower end of the tubo it was easily retained in a vertical position with about four-fifths of its length submerged, its flaVplato being turned towards the boat carrying the bell. With this simple apparatus Co'lladon was able, to hear, with perfect distinctness? tho blows of the hammer on tho boll across tho widest part of Lake G«ne\a, when . tho calculated distanco between tho two boats Was mot less than eight nnlos The sounds I i which he heard appeared as if thoy had been caused by some metallic body striking tho bottom o£> the tttbe r and -they were as d-stinct at eight imlee'tts at a few hundred feet from the bell. One set of observations wa3 made during a strong wind. The waters of the lake, whi6b > Were first calm, became violently agitated, and it was necessary to r koet) the boat in pasition be means of several anonors, yet, notwithstanding, the noise of the waies that struck the tube, <he toot observations with the 6anio ae-' enraoy, as when the air and wat*r / wero 6till, And no states, 'I am oonvinoed that by employing a bigger bell, iand improving or enlarging tho 'hearing apparatus, easy communication could be effected mnder tho water of a lako or of to fifteen or twenty iengues.' "Besides their usefulness in warning vessels of their approadh to the .land and to dangers, v submarine sound-signals may be used as a means of communication between vessbls at Eea^ , Per this purpose'the sound-producing v boll, immersed in,water,hold in a tank, is installed, in the forepeak of the vessel, inside of the hull, and may be operated automatically or by hand. As a means of communication be-1 tween submarine boats in 'a btato of submer-

wince this method of signalling has a special neldkOf utility. During the tests of submarine boats'm May, 1907, communication was, in this manner, kept up between the Octopus and the tender Starling. Signals were communicated from the Starling to tho Octopus, telling when tho latter had crossed the finish hnes'and when to come to the surface, and distinct messages were received in return from the submerged vessel. t i "The maritime community has availed itself rtore and more of the facilities which have thus been provided by tho fostering care of the various Gcvemmente, with'a view of lessoning danger'in navigation and delay in transportation, and an .increasing number of vessels have, year by -year, been furnished with submarine sound-receivers, and, for the convenience of Underwriters in determining rates of insurance, the 'American Bureau of Shipping has noted ill •The i Record of American ond Fireign Shipping,' which of the vessels are bo equipped. "/The saving of time brought about by enabling vessels to reach port instead of being delayed by ,fog. and losing tides is being constantly exemplified. The Lucama, while approaoning New York on 6ne, occasion, made all three light-vessels by submanrie-bell sounds, which constituted the solo guide and we read in the G&zctto' that the captain of the Kaiser 'Wilhclm der Grosso during the course of a voyage to New York, when surrounded by a dense fog off the coast near Fire Island light-vessel, heard the submarine bell and was enabled to steer by it, when, as it subsequently transpired ho was twelvo nautical idiles distant from the siknal-station. At 646 a m tho sound of the bell was heard to starboard,, and, owing to the fog, the 6hip, which was 6ome distance out of nor position, was guided solely by theso boll signals, and the , course was altered by the sounds.heard from the light ship, though the fog-horn was wholly inaudible." .