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Historical Magnetic Variation/Declination
From: Frank Reed CT
Date: 2004 Jun 13, 19:56 EDT
From: Frank Reed CT
Date: 2004 Jun 13, 19:56 EDT
I had some time today to put together a few different ways of viewing the historical magnetic declination/variation maps from the USGS. There's a large animated GIF as well as a frame-by-frame viewer available on my web site here:
http://HistoricalAtlas.com/mag
Looking at those isolines, it's interesting to consider how nearly magnetic variation came to being a reasonable method for determining longitude. As Halley discovered in th early 18th centurt, if only the lines were as "well behaved" in the rest of the oceans as they were in the South Atlantic in that period, it just might have been workable. Who knows... longitude might have been found with a magnetic compass instead of a sextant or chronometer.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
http://HistoricalAtlas.com/mag
Looking at those isolines, it's interesting to consider how nearly magnetic variation came to being a reasonable method for determining longitude. As Halley discovered in th early 18th centurt, if only the lines were as "well behaved" in the rest of the oceans as they were in the South Atlantic in that period, it just might have been workable. Who knows... longitude might have been found with a magnetic compass instead of a sextant or chronometer.
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
