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Earth's Magnetic Pole


evenfall
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This is exactly what I have been trying to get across for the years I have been here.

I guess it takes being a paleomagnetist to be heard.

 

There is also another phenomena that goes along with this,the annual westward slippage.(proper motion).

 

The 2 combinations are (may) be one.

 

If the celestial magnetic sphere is moving it would effect the Earths and other planets magnetic anomolies.

 

To go into details would take volumes.

The main thing is...to determine a magnetic reading from 150 years ago would take quite a bit of calculations.

And it has only been kept tract of less than that.

 

So for one to say he can accurately determine what a person saw 150 years ago is quite a bold statement.

 

OK enough sorry.

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Nothing new under the sun. :huh:

 

"In the last one hundred years the compass needle has changed its relationship to the north line in the central portion of North Carolina about 4.5 degrees of arc. This means that in the central portion of North Carolina a surveyor starting from the same corner used in 1800, and retracing at the present time (1900) a line, say, 1 mile long, between two contigous properties, using the compass bearing of 1800, the corner at the other end of the line would be shifted 399 feet from its original position.

 

"During the last ten years the compass needle has changed its direction on an average in North Carolina about 3 minutes of arc each year. A surveyor in North Carolina, by making use of the county meridians, as he is required by law to do, should determine for himself the amount of the secular change, and not be guided in the future solely by the changes in the compass bearings of old lines when they are retraced.

 

"The only place in North Carolina where we have a sufficient number of observations to warrant a discussion of the secular variation on the magnetic declination is Newbern, and even there our results only go back to 1750."

 

---REPORT TO THE SUPERINTENDENT OF THE COAST AND GEODETIC SURVEY, Progress of the work from July 1, 1898 to June 30, 1899, by James Baylor and Daniel Hazard, (US GOVT PRINTING OFFICE, 1900) pp. 906. 908.

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GEO*Trailblazer 1 -

 

I don't know when, if ever, official boundary surveying was done in the U.S. with magnetic compasses without knowing the local declination between magnetic North and true North. I believe that it was not done, even 150 years ago. Any professional surveyor would know to calibrate (declinate) their compass using the stars.

 

Given the above, concerning old surveys, it does not matter where the magnetic pole was at the time. One could argue that their declination wasn't always as accurate as it could be, but that again is independent of where the magnetic pole was at the time.

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