DEEP SOUNDINGS.

Hawera Star, Volume XLVI, 5 February 1927, Page 11

DEEP SOUNDINGS.

I""* CONSIDERABLE interest has been caused by the report that, the Japanese naval surveying ship Manshu recently obtained a sounding of 31,000 feet between Izu nncl the Bonin Islands; and it has been stated that this is the deepest known spot in the Seven Seas, easily beating the famous Tuscarora Deep of 27,900 feet which was named after the American warship which made the sounding (declares the London . Daily News). The new sounding certainly does 'beat this, but it is itself by two others. The German surveying ship, Planet, in 1914, got bottom at 32,112 feet east of the Philippine Islands, while the Manshu herself, surveying in August, 1924, failed to find bottom wtih 32,64(3 feet of wire out.

It is interesting to note that, whereas there are quite a number of elaborate sounding machines on the nlarket —■ machines which register the depth of water by the compression of air in a sensitised tube —which arc used bv all liners, it is still necessary, _ when it comes to great depths like this, to employ the same method that was employed by the Vikings and Phoenicians: a heavy weight on the end of a line.

Nowadays the line is the finest piano wire, but when Ross was surveying the Weddell Sea he used an ordinary cod line, which was constantly breaking. On one occasion he reported 4000 fathoms —24,000 feet —and no bottom, which was regarded as a wonderful sounding. Unfortunately, it was afterwards proved that his men failed to notice the slight check on the line which told that the weight had hit the bottom of the sea, and had continued to allow the line to run out by its own velocity, and by the tide. Actually there was a depth of 2000 fathoms of water in this spot.