Hi ChiLian,
That's very interesting - I haven't heard before of a dial delineation being
pre-distorted in this way to allow for the penumbra effect.
Perhaps the reason that the 1 minute correction that you adopted was too much
is that your latitude (24.79 N) is so much less than the
.
Regards
Chris Lusby Taylor
- Original Message -
From: JOHN DAVIS
To: [EMAIL PROTECTED] ; [EMAIL PROTECTED]
Cc: Sundial List
Sent: Wednesday, February 13, 2008 8:39 AM
Subject: Re: Shadow Tapering
Hi ChiLian,
That's very interesting - I haven't heard before of a dial
Hi Patrick, John C and the List,
The problem of the shadow not properly filling the noon gap is the same
umbra/penumbra related one which affects the reading accuracy of dials with
'solid' gnomons at all times of the day. This is usually ignored by dial
makers but I know of one
Mac,
You are absolutely right.
The problem is that normally I hit the 'reply' button to reply to an
email. In all emaillist emails I receive this works fine. Only in
this emaillist the replybutton creates only the address of the
original sender and not of the list-server. So I have to 'reply
On Feb 10, 2008, at 6:00 AM, Patrick Powers wrote:
Indeed, if you want a bit of fun, if you have Google Earth and care
to type
in 52 45' 16.28N, 01 08' 12.33 W then you go directly to the
second of
these dials.
Even if you don't have Google Earth you can go to the http://
Tony all:
One more comment on shadow tapering solutions. Your solution Tony is to
decrease the size of the Noon Gap to compensate for the decreased observed
shadow width. My two different proposed solutions that I described in my
last letter involved changing the width of the gnomon instead of
Dear Patrick:
I completely agree with you Patrick! Tubular gnomons are good. And I think
your comment directly pertains to the shadow tapering problem. In fact,
using tublar gnomons could be the best solution to the shadow tapering
problem. If you make the dial with a tublular gnomon, and you
If you make the dial with a tublular gnomon, and you design the face so
that the time is read from the center of the shadow instead of the edges of
the gnomon's shadow, then you eliminate the Noon Gap. Do you think this is
the best solution?
From the point of view of an accurate dial, one that
