DEPTH FINDING.

Hokitika Guardian, 15 September 1923, Page 4

DEPTH FINDING.

A WONDERFUL CONTRIVANCE. SYDNEY, Aug. 29. If men like Newton could revisit the earth to-day, they would probably : stand aghast at the extraordinary development of science. There is now in Sydney the American cruiser Afilwau--1,-ec, fitted with an extraordinary deptlifiinding apparatus, the object o! the visit being to give the members of the Pan-Pacific Science Congress an opportunity to witness a demonstration of its powers. The Sonic method of sounding, according to Professor Sir Edgeworth David, will probably revolutionise modern methods of charting coasts and locating dangers to shipping, such ns submarine reefs and banks, the method being more rapid and more economical than that of sounding by means of the lead and the line. The apparatus depends for its working on j a method of echoing, just as, in the j case of sound waves, one throws one s ( voice out in an area where there is a ; good echo. Tn the Sonic method of j sounding, an electric impulse is sent j downward front the ship to the sea . bottom, and is reflected back again to 1 a receiver on the ship. The deeper the j water, the longer is tlie time interval ; between the sending out and the echo- j ing out of the impulse. A simple table ■ enables tho observer rapidly to convert tho time interval into fathoms. Thus the depth is found. The wonderful apparatus, it is considered, will do much to speed up the charting of the oceans. The apparatus is the outcome of devices for protecting submarines during the war, *