MAGNETIC SURVEY GIVES WORLD IMPORTANT FACTS

Bay of Plenty Beacon, Volume 14, Issue 82, 6 January 1950, Page 4

MAGNETIC SURVEY GIVES WORLD IMPORTANT FACTS

New Zealand’s present contributions in the international investigations into terrestrial magnetism—< a problem that has engaged the attention of scientists for centuries—are of considerable importance. . Fifty years ago a magnetic survey of New Zealand was commenced and within ten years magnetic observations had been made at 334 points scattered over the North and South as well as Stewart, Snaresf Auckland, Campbell and Chatham Islands. Since 1941 over 200 points on all these islands have been re-occupied. In this interval of §ome 40 years varying rates of change in magnetic forces and directions had taken place. Hydrographers who prepare international navigation charts now seek and get data amended by this re-surVey. Within New Zealand, mariners, aviators, engineers, surveyors, and geophysicists are supplied each year by the Magnetic Survey—a branch of the Department of Scientific and Industrial Research—with charts of any magnetic element they require. The rigours of magnetic survey field work, in which the staff cover some 100,000 miles over New Zealand and outlying islands, sometimes necessitate working under arctic and sometimes under tropical conditions.

In the past stqdy of the earth’s magnetic field has been restricted to land based and sea-borne observations from non-magnetic ships. Recently the Magnetic Survey obtained an airborne magnetometer which is being checked over at Dominion \ Physical Laboratory. Very soon it will be flown over the thermal regions of the North Island where/an aerial magnetic survey should, in weeks, reveal geological features which land-based methods would take many years to reveal. Airborne methods, while very rapid, are so far restricted to one element, and land observation probably for some years yet will remain the only fully complete method of surveying. With a few landbased measurements for control purposes, airborne magnetometer methods as used overseas have proved entirely satisfactory for rapid geological reconnaissance.