Art Carlson contributed
>
>I agree that a shadow method is likely to be easier and more precise
>than using either a compass or GPS, but I have some comments on your
>exposition. First, the clock time of the readings is not
>important. In the afternoon, you want the locations where the shadow
>of the nodus crosses each circle, regardless of what your watch says
>the time is. Second, the accuracy of the result can be compromised if
>the ground is not level from East to West. For high precision, you
>will first need to prepare a level surface for the shadows to fall on.
>
Several people are now using my 'Meridian Alidade' designed and made expressly
to lay out local meridian lines. I found it easy to make an instrument which
aligned with the meridian, it was getting that alignment accurately back onto
the ground which prompted me to make the first prototype. See a picture of the
instrument on my webpage at URL below.
Tony Moss
P.S. One ingenious fellow (and now one lady too!) uses the same instrument for
determining the declination of a wall by setting it to the meridian and then
rotating until perpendicular to its own image in a plane mirror set true to the
wall.
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\ T \ / M ** ******
\\ - O - ** **
\\ L / \ S ** *******
*\\ ** **
*\\ ******* *******
**\\
***\\ Tony Moss, Lindisfarne Sundials
*****\\ 43, Windsor Gardens, Bedlington,
*******\\ Northumberland, England, NE22 5SY,
**********\\ 55° 07' 45" N 1° 35' 38" W
Tel/FAX +1670 823232
Mobile: 07970 208 540
Website: http://www.lindisun.demon.co.uk
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Horizontal, Vertical, Declining, Analemmatic, Equatorial, Polar
and Capuchin Sundials individually made in solid engraving brass
or phosphor bronze. Professional-quality Dialling Scales,
'engine-divided' Meridian Layout Instruments with software.
Analemmatic dial plots - any size for any latitude.
Graduation, re-cutting and restoration of scales.
'Lintique' patination of brass.
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