[Antennas] Using GeoClock To Find True North

Mon, 18 Feb 2002 18:40:41 -0500

As the sun rises, the tip of the shadow will move from near West to a
point approaching North .. then, after Noon, it will approach East.
Therefore, the segment from 0900 'tip' to 1000 'tip' will be somewhere
along a SW/NE line.  Sooooo .. the permendicular bisector of that
segment will be close to NW/SE !
Don
N8DE

Jim Clark wrote:
> 
> Just a thought
> As the sun "rises" between 9 and 10, the 10 o'clock shadow will be lower
> and back in the E/W plane, maybe?
> 
> Jim, N5QL
> 
> -----Original Message-----
> From: Don Havlicek [mailto:[email protected]]
> Sent: Monday, February 18, 2002 5:17 PM
> To: Jim Clark
> Cc: [email protected]
> Subject: Re: [Antennas] Using GeoClock To Find True North
> 
> No, no, no .... if the two marks were made at 0900 and 1000, then N/S
> line would be somewhere close to NW/SE !!!!!
> 
> Better to do this:
> 1.  Drive the stick into the ground and mark the end of its shadow at
> some time in the early morning, recording the clocktime.
> 2.  Mark the the end of its shadow again at a time which is the SAME
> AMOUNT AFTER noon that the first mark is BEFORE noon.
> 3.  Now do what you suggest:  the perpendicular bisector of the segment
> between the two points is APPROXIMATELY the N/S line.
> 4.  Better way:  Use the North Star as someone previously mentioned.
> 5.  Best way:  Use a compass and apply the correct declination
> correction.
> Don
> N8DE
> 
> Jim Clark wrote:
> >
> > This sounds like a job for Indiana Jones or Laura Croft. (I'll take
> > Laura!)
> >
> > Egyptian compass:
> >
> > Pick a nice sunny day.
> > Drive a stick several feet long into the ground straight up.
> > Mark the end of its shadow with a small stick.
> >
> > About an hour or so later mark the shadow's position again.
> > Draw a line between these two points.
> > A line perpendicular to that line is north / south.
> >
> > Jim, N5QL
> >
> >
> >
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> 
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