Hallo Mark,
excellent! Thank you so much for the NASS info and your explanation. I will
asap dig into that (and hope to find the Nass link).
Thank you again and kind regards
Siegfried
Siegfried Netzband
Hebelstr. 12
75233 Tiefenbronn
Tel: 07234 2802
Fax: 07234 942909
Mob: 0151 53083636 / 0160 1531634
E-Mail: siegfried.netzb...@t-online.de
Skype: siegfried75233<http://www.ferienhaus-frieseneck.de>
-----Original-Nachricht-----
Betreff: Re: Interesting Moon Dial
Datum: 2023-07-11T22:05:33+0200
Von: "Mark Montgomery" <mark.montgomery2...@yahoo.com>
An: "sundial@uni-koeln.de" <sundial@uni-koeln.de>,
"siegfried.netzb...@t-online.de" <siegfried.netzb...@t-online.de>
Hello Siegfried,
This is a wonderful dial. The construction of this moon dial is given by
Jacques Ozanam in 1693 in his "Cursus Mathematicus: or A Complelat Course
of the Mathematicks." Vol V Part III, "A Treatise of Gnomonicks", Problem
XX. This work is available from the NASS website Shadow Catchers series.
To read the dial you must know the age of the moon, or number of days since
the last new moon. The lunar age is given next to the meridian (noon) line
with 1-15 on the left side and 16-29 on the right side. These numbers
apply to the lines perpendicular to the meridian. Find the line for the
current lunar age and locate where the moon's shadow intersects this lunar
age line. There will be a slanted or curved line close to the
intersection. This is the local solar time line. Follow the curved line
the the edge of the dial to read the local solar time from the moon's
shadow.
Hope this helps,
Mark
On Monday, July 10, 2023 at 06:17:46 AM CDT, siegfried.netzb...@t-online.de
<siegfried.netzb...@t-online.de> wrote:
Dear sundial friends,
came across an interesting moon dial which is quite different from all the
other moon dials I did see up to now (
<https://kabinett.mapublishing-lab.uni-koeln.de/objekte/monduhr> ).
However: I cannot read it, neither do I understand the way they calculated
the lines on the dial to (may be) read off the time.
The dial does not have the usual numeric list where you can determine the
age of the moon with the aid of the size of the illuminated moon. The age
of the moon, i.e. the angle between moon and sun is needed to determine
time using the moon shadow on a sun dial at night.
How do you read this dial and what is the basis (theory) for the lines to
read of the time on this dial? Is there someone who can help? I would be
very thankful for any help or advice.
Thank You for Your help!
Regards
Siegfried Netzband
[https://kabinett.mapublishing-lab.uni-koeln.de/fileadmin/_processed_/8/7/csm_KGS_BEL-Monduhr_11cafd00a9.jpeg]
Siegfried Netzband
Hebelstr. 12
75233 Tiefenbronn
Tel: 07234 2802
Fax: 07234 942909
Mob: 0151 53083636 / 0160 1531634
E-Mail: siegfried.netzb...@t-online.de
Skype: siegfried75233<http://www.ferienhaus-frieseneck.de>
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