AID TO SHIPPING

Dominion, Volume 13, Issue 75, 22 December 1919, Page 7

AID TO SHIPPING

NEW METHOD OF FINDING POSITION AT SEA , SOUNDS UNDER WATER An interesting now method—known as ffub-aciucous sound r«ui£ing—-of dotwuiijiin? tho position-of a ship at sea is explained in a statement issued by the Admiral tv The system, is is pointed out, been of jirfiat vfihio for war operaturnsi and will, if 'developed, be of great tinns shipping under peace condiFrom a broad outline of tho method, L I l ™,' 7or fITO hydrophones are established under water at distances f , a 'i ollt flvo miles, each one being on short ACn i l ° rccordin S ation If r i?'i A . Sficon 'l "coroing station is l' S « H nnT -distance, tliese wL p i°" S for " tho extremities of » ? •£" ow ! 1 , len R th «nd hearing. Any shin within tho working limits of the=e stations, and well situated in respect to the base line, can have her position exactlv determined by causing P a subSh'charce S ' oD ' S "° h M (,roppin » 11 The nosition is obtained bv photogra■Dhicallv recording and measuring at each 6tation tho differences of time of tho receint of tho sound of the explosion at the hvoronhones. A vessel employing this method must be fitted with wireless teleRraphic apparatus, arranging beforehand for tho receipt of the sound of the exPlosion. and transmission of the subsetment information, from tho control recordine station. A vessel approaching a port in a fox. if is stated, could rely on a Bories of nositions bv sound ranging, and reconcile them with her movements in tho intervals between them.

Durimr tip v.ar minefields were laid 'Mid bombaulin-; positions for ships o'ut of sitrht of land were found with the greatest nrccision; explosions in minefields T; cre recorded and their positoins accurately fixed, onMilijn; patrols !o proceed to the spot elucidate the cause. Sound m.i.ein" st'itio.is ar,> pi present established at St. Manraret's Bay (near Dover). Easton Broad (near Lowestoft), rkmboroiißh llwul, Peterhead, and Lerthe last three are, however, being Closed ip .the interests of economy. Shipping companies and others interested with a view to adopting this methotf I).tb.invited to communicate with the Admiralty bv letter in the fi r -t instance. lActnal trials may possibly be arralisted. "The method." it is observed, "is at present onlv in its infancy, and cannot lie. said to be at ureseiit suitable for commercial use It is, of course, capable of (Treat development, and it will proljnhlv be found .that only very small explosive charges are required to Hve the records.