Surveying terrestrial magnetism in time and space
Charts marked with the lines of magnetic variation have been published since Halley's Atlantic chart of 1701. It was already known that the location of the magnetic poles shifted over time, and that the north and south poles were not diametrically opposite. As more seafarers penetrated the Sout...
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2005
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Online Access: | http://dx.doi.org/10.3366/anh.2005.32.2.346 |
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credinunivpr:10.3366/anh.2005.32.2.346 2023-05-15T14:10:49+02:00 Surveying terrestrial magnetism in time and space McConnell, Anita 2005 http://dx.doi.org/10.3366/anh.2005.32.2.346 en eng Edinburgh University Press https://www.euppublishing.com/customer-services/librarians/text-and-data-mining-tdm Archives of Natural History volume 32, issue 2, page 346-360 ISSN 0260-9541 1755-6260 Agricultural and Biological Sciences (miscellaneous) History Anthropology journal-article 2005 credinunivpr https://doi.org/10.3366/anh.2005.32.2.346 2022-04-01T04:18:54Z Charts marked with the lines of magnetic variation have been published since Halley's Atlantic chart of 1701. It was already known that the location of the magnetic poles shifted over time, and that the north and south poles were not diametrically opposite. As more seafarers penetrated the Southern Ocean, isogons on the charts were extended southwards with greater confidence. At sea variation was measured by comparing compass direction with the Sun's midday shadow. In polar regions, where horizontal force is too weak to attract a compass needle, the location of the pole was sought by observing the inclination of a dip needle swinging in the magnetic meridian, which would hang vertically at the pole. The Fox dip circle, developed in 1834, was the first instrument capable of measuring dip and intensity at sea, and allowed James Clark Ross to predict the location of the South Magnetic Pole. In 1902 Discovery's crew landed an observatory ashore, but a trek on to the plateau failed to reach the magnetic pole. Success came in 1909 during Shackleton's Nimrod expedition, when T. Edgeworth David's party reached the zone of maximum dip. Over the following years data from photographic magnetometers recording declination, vertical and horizontal intensity were routinely made at the various national bases round Antarctica; they contributed to our knowledge of the Earth's internal magnetism and on the solar influences. Article in Journal/Newspaper Antarc* Antarctica Southern Ocean Edinburgh University Press (via Crossref) Southern Ocean Nimrod ENVELOPE(165.750,165.750,-85.417,-85.417) Archives of Natural History 32 2 346 360 |
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Open Polar |
collection |
Edinburgh University Press (via Crossref) |
op_collection_id |
credinunivpr |
language |
English |
topic |
Agricultural and Biological Sciences (miscellaneous) History Anthropology |
spellingShingle |
Agricultural and Biological Sciences (miscellaneous) History Anthropology McConnell, Anita Surveying terrestrial magnetism in time and space |
topic_facet |
Agricultural and Biological Sciences (miscellaneous) History Anthropology |
description |
Charts marked with the lines of magnetic variation have been published since Halley's Atlantic chart of 1701. It was already known that the location of the magnetic poles shifted over time, and that the north and south poles were not diametrically opposite. As more seafarers penetrated the Southern Ocean, isogons on the charts were extended southwards with greater confidence. At sea variation was measured by comparing compass direction with the Sun's midday shadow. In polar regions, where horizontal force is too weak to attract a compass needle, the location of the pole was sought by observing the inclination of a dip needle swinging in the magnetic meridian, which would hang vertically at the pole. The Fox dip circle, developed in 1834, was the first instrument capable of measuring dip and intensity at sea, and allowed James Clark Ross to predict the location of the South Magnetic Pole. In 1902 Discovery's crew landed an observatory ashore, but a trek on to the plateau failed to reach the magnetic pole. Success came in 1909 during Shackleton's Nimrod expedition, when T. Edgeworth David's party reached the zone of maximum dip. Over the following years data from photographic magnetometers recording declination, vertical and horizontal intensity were routinely made at the various national bases round Antarctica; they contributed to our knowledge of the Earth's internal magnetism and on the solar influences. |
format |
Article in Journal/Newspaper |
author |
McConnell, Anita |
author_facet |
McConnell, Anita |
author_sort |
McConnell, Anita |
title |
Surveying terrestrial magnetism in time and space |
title_short |
Surveying terrestrial magnetism in time and space |
title_full |
Surveying terrestrial magnetism in time and space |
title_fullStr |
Surveying terrestrial magnetism in time and space |
title_full_unstemmed |
Surveying terrestrial magnetism in time and space |
title_sort |
surveying terrestrial magnetism in time and space |
publisher |
Edinburgh University Press |
publishDate |
2005 |
url |
http://dx.doi.org/10.3366/anh.2005.32.2.346 |
long_lat |
ENVELOPE(165.750,165.750,-85.417,-85.417) |
geographic |
Southern Ocean Nimrod |
geographic_facet |
Southern Ocean Nimrod |
genre |
Antarc* Antarctica Southern Ocean |
genre_facet |
Antarc* Antarctica Southern Ocean |
op_source |
Archives of Natural History volume 32, issue 2, page 346-360 ISSN 0260-9541 1755-6260 |
op_rights |
https://www.euppublishing.com/customer-services/librarians/text-and-data-mining-tdm |
op_doi |
https://doi.org/10.3366/anh.2005.32.2.346 |
container_title |
Archives of Natural History |
container_volume |
32 |
container_issue |
2 |
container_start_page |
346 |
op_container_end_page |
360 |
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1766282910236672000 |