AIDS TO NAVIGATION.

New Zealand Herald, Volume LXIII, Issue 19405, 13 August 1926, Page 14

AIDS TO NAVIGATION.

CHARTS A OENTURY OLD. PARTLY UNSURVEYED COAST. Less than one-twentieth part of tho Australian coastline is adequately charted and there Still exist stretches of thousands of mijos which havo never' been surveved. Inquiries made lately at the hydrographic branch of the Royal Australian Navy in Melbourne revealed the almost primitive condition of hydrographic information concerning Australian waters. The first charts of Australia were constructed by Captain Cook in 1770, and by Captain Matthew Flinders in the years 1802-4, The work of Cook was approximately accurate, but far from complete, arid the work of Flinders, whilo remarkably exact, did noli approach in precision tho work which is dono at tho present day. Nevertheless, for .some pai'ts of tho coast these century-old charts, prepared under tho direction of Flinders, are the only existing aids to navigation. A number of short surveys havo been mado since the construction of tho Flinders chart, but the last work of any extent was dono in 1970 by Captain Bedwell, who was at. that time tho chief authority on the existing charts of tho Great Barrier Roof region. It is now considered by the Hydrographic Department that the inner route along the Queensland coast has been surveyed in sufficient detail. for ships of medium draught/ but for tho larger vessels of the present day any survey completed before 1900 nuist be considered of doubtful *valiie. Prior, to the arrival of H.M.A.S. Moresby last year no connected triangulation of the Great Barrier Reef and the associated coastline had been attempted. .This work is well in hand, and will probably bo comploted within the next few years. Tho tidal information concerning Australian waters is also very scanty and this is rendered 4 more serious matter by the fact that tides in tropical Australia are erratic and the ebbing and flowing current's may be exceedingly strong. Although attempts have been made to construct-tido tables for Thursday Island, no regularity in rise and fall has been observed, and for this reason alone tho region is dangerous to even experience navigators. It is significant that during recent surveys shoals havo been found in the main trade routes.