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Hi David,
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if I
have not made great mistakes in my calculations - done quickly :-)
- you cannot inscribe any hour lines on your polar sundial facing
north.
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At Lat.
52N on summer solstice, the Sun rises at 3h 47m (civil time) or at 3h 45m apparent Solar time.
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At 4h
apparent time, the sun has (year 2004) : Azimuth= -127.3508d
and Altitude=1.7789d.
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With
these values and with a gnomon 13
units high, the shadow point falls at 22.5 units from the dial center westward
and at 11.3 units downward : for this
reason out your dial.
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In the next hours, and in different
days, the things become worse and the shadow point moves away.
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For
example at 4h30m (apparent time)
the shadow falls at 31.4 units from the center westward, etc.
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At 6h
the Sun passes in front of the dial.
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Obviously the things are symmetrical in the
evening hours.
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Best
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Gianni Ferrari
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- Re: Inferior polar dial Gianni Ferrari
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