Geomagnetic survey provided the rationale for James Clark Ross' southern expedition in Erebus and Terror from 1839 to 1842. Aside from the bold success of penetrating pack ice in sailing ships to find the polynia (open water) of the Ross Sea, he determined that the South Magnetic Pole was behind the range he named after Lords of the Admiralty and could not be attained by sea.
Later expeditions undertook more varied scientific programmes but geomagnetic survey remained a central activity. By the time that Louis Bernacchi was studying meteorology and terrestrial magnetism in Melbourne Observatory (1895 to 1898) the instruments had become sophisticated.The main tools of trade were the Monofilial Magnetometer and the Dip Needle. These two devices between them could determine magnetic variation, dip and intensity (the force with which the needle attempts to dip). The Kew pattern monofilial magnetometer (see photo in University of Queensland Physics Museum) was so named as the magnet within the apparatus was suspended by a gold filament allowing it to swing freely according to the external magnetic influences. One of the aims of the Discovery expedition was to make observations of terrestrial magnetism in concert with Von Drygalski's Gauss expedition and some land based observatories in lower latitudes (Christchurch, Capetown and .......) . Complete sets of observations over the two years of the expedition were possible using Professor Eschenhagen's apparatus. Louis Bernacchi missed the departure of the Discovery as he was still at the Potsdam observatory near Berlin learning procedures for these self-recording instruments. These made a photographic record of the observations using a clockwork mechanism. He caught up with the expedition in Christchurch after taking the Orient liner Cuzco to Sydney then connecting to Lyttleton. He also brought new types of Milne seismograph (earthquake recorder) and gravity pendulums. The following images show the use of the magnetometer and dip needle during Mawson's Australian Antarctic Expedition from Webb, E. and C. Chree (1925).
The Kew Pattern Monofilial Magnetometer-----Eric Webb in the Magnetometer Hut-Using the Lloyd-----Creak Dip Circle
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