68. Three-Component Magnetometer (1946)
Until the mid-20th century, the magnetic compass was the primary tool for exploring, mapping, and surveying. However, establishing the direction and strength of Earth’s magnetic field at all points over a landmass as large as Canada is an enormous task. To resolve this, in 1946, development began in Canada of an airborne magnetometer that could measure three components of the magnetic field (horizontal direction, dip, and field strength). The project involved the Dominion Observatory, the Department of Defence, and the University of Toronto, with the first prototype system flown in 1950.
Between 1951 and 1955, Paul Serson and colleagues at the Dominion Observatory built the instrument shown. The first experimental high-level flights took place in 1953 using an RCAF Northstar. In 1955, it was used for a systematic survey of Manitoba, Saskatchewan, and Alberta. Using civilian aircraft, six additional high-level surveys were flown between 1957 and 1968, completing coverage of Canada.
This resulting information provided the first Canadian Geomagnetic Reference Field, which continues to be used to provide the compass directions included on all topographic maps. Changes through time are captured through ground measurements at a network of observatories and, in recent years, through international satellite observations.
Category: Equipment and Instrumentation
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