John Brosnahan wrote:
>
> >Ed,with respect, I have heard the term declination used all my
> >life by those that were in the profession of surveying, navigating,
> >etc. I took the time to look it up in Webster's because I was
> >puzzled by your (and others) statements that it was not correct.
> >Webster's says:
> >
> >"Angular distance north or south from the celestial equator measured
> >along a great circle passing through the celestial poles."
> >
> >Doesn't that accurately describe what has been talked about?
>
> (No, sorry, but then the deviation is not correct either.)
>
> That is not what is being talked about. The use of declination in
> your case is for astronomical purposes--where the position of a
> star is defined in terms of declination and right ascension.
>
> This use of declination in the discussed case is for surveying
> and navigating and aligning Yagis on Heard Island and is
> referenced to the earth's magnetic field, and is the correct term.
>
> The MAGNETIC DECLINATION, called angle D, is the angle between
> Geographic North and Magnetic North.
>
> Maybe the flyboys use deviation but the CORRECT term
> (Physics and Surveying) IS declination.
>
> BTW The MAGNETIC DIP or INCLINATION, which is the angle I,
> measured between the horizontal and the direction taken by a freely
> (3D) suspended magnetized needle. At the magnetic N and S poles
> the dip is vertical (and at the magnetic equator it is horizontal).
>
> 73 John W0UN
>
> ref. Surveying 5th Ed. Bouchard and Moffitt
> Principles of Physical Geology 2nd Ed. Holmes
> John Brosnahan
> La Salle Research Corp.
> 24115 County Road 40
> La Salle, CO 80645 USA
>
> voice 970-284-6602
> fax 970-284-0979
> email broz@csn.net
>
> --
> FAQ on WWW: http://www.contesting.com/towertalkfaq.html
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> Sponsored by Akorn Access, Inc & KM9PWell, you physicists may like
> declination, but us fly-boys prefer
deviation. There are more flyboys than physicists, I'd wager. "It's all
a matter of taste," he said, as he kissed the cow.
Regards,
Madison
W5MJ
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