Re: East/West Vertical Bifilar Sundial

[Roger Bailey]

From: Roger Bailey 
Sent: Sunday, May 28, 2017 9:32 PM
To: Nathaniel Shippen ; sundial@uni-koeln.de 
Subject: Re: East/West Vertical Bifilar Sundial


Hello Nathaniel,

Yes, it is quite doable. Here is a sketch produced with Fer De Vries Zon 2000 
for a bifilar in Honolulu Hawaii, lat 21.3° long 158°, X thread 25, Y thread 
15, dec 85° east of south, Inc 88°.

The sketch was too big for the SML size filter. This is the note without the 
sketch, available on request.  

The red lines show the threads, the black lines are the hour and declination 
lines. Doable? yes. Understandable? no. To understand read the NASS Compendium. 
Here over the last 20 years there are over 60 documents related to bifilar 
sundials: articles, programs, presentations by the giants in the field, Fred 
Sawyer, Rafael Soler Gaya, Dominique Collin, Gianni Ferrari and Fer de Vries. 
Rafael Soler Gaya has designed and commissioned some excellent bifilars based 
on catenary curves and conic sections in Mallorca. See my presentation on 
Sundials in Mallorca here. 
https://drive.google.com/open?id=0B14iMmxzLvJWRkpnSk1jbE5odTg Fred Sawyer has 
published on the origins of bifilar sundial starting in 1978. Fer De Vries 
program is easy to use to show what the lines look like. Alll this information 
is available to all NASS members. see www.sundials.org  

Regards, 
Roger Bailey
Walking Shadow Designs


Sent: Sunday, May 28, 2017 1:35 PM
To: sundial@uni-koeln.de 
Subject: East/West Vertical Bifilar Sundial


I've seen some info on bifilar sundials, and they look very interesting. I 
thought I would try to make a simple one (if that is possible). An east and/or 
west facing vertical dial would be the most useful at my location. Actually the 
surfaces I would be using decline a little south of west and north of east (and 
also recline slightly). I would be sketching in the time marks (Hawaii 
Standard) empirically since I am also some 8 degrees west of the standard 
meridian.


Is this doable? Are the computations for the threads and the point of origin 
for the hour lines fairly simple? If yes I'll dig in and do the necessary 
research, just don't want to be off on an impossible quest.


Thank you in advance for your help!


Nathaniel Shippen





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Re: sundial Digest, Vol 137, Issue 20

[Harris Morrison]

To discuss 
Harris

HarrisMorrison
4855 draper
Montréal,  H3X3P6
har...@shepherdswatch.com
514-487-5544


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>   1. St. Hildevert (Fred Sawyer)
>   2. Re: St. Hildevert (Dan-George Uza)
>   3. Re: St. Hildevert (Fred Sawyer)
>   4. Re[2]: St. Hildevert (jmikes...@ntlworld.com)
>   5. Re: Re[2]: St. Hildevert (Fred Sawyer)
> 
> 
> --
> 
> Message: 1
> Date: Sat, 27 May 2017 13:04:58 +
> From: Fred Sawyer 
> To: Sundial List 
> Subject: St. Hildevert
> Message-ID:
>

East/West Vertical Bifilar Sundial

[Nathaniel Shippen]

I've seen some info on bifilar sundials, and they look very interesting. I
thought I would try to make a simple one (if that is possible). An east
and/or west facing vertical dial would be the most useful at my location.
Actually the surfaces I would be using decline a little south of west and
north of east (and also recline slightly). I would be sketching in the time
marks (Hawaii Standard) empirically since I am also some 8 degrees west of
the standard meridian.

Is this doable? Are the computations for the threads and the point of
origin for the hour lines fairly simple? If yes I'll dig in and do the
necessary research, just don't want to be off on an impossible quest.

Thank you in advance for your help!

Nathaniel Shippen
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[no subject]

[tonylindisun--- via sundial]

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eigentliche Nachricht steht dadurch in einem Anhang.

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Hi Frank and everyone,
  Some years I replaced a dial in Cheshire 
where the thieves had removed a heavy stone pedestal down a steep,  twisting 
and very narrow path.  They almost deserved it for the herculean effort 
involved.  My bronze replacement was set as previously described with a 
profiled gnomon 'tenon' set in mortar PLUS the circular dial plate was set 
using silicone adhesive into a circular cavity preventing easy access for any 
kind of lever under the plate.  As far as I know this dial is still in place.  
The rounded tips of bolts showing above the plate can indicate an additional 
firm fixing from below as a 'thief discouragement' device.  Contrast that with 
an English stately home where the valuable dial was secured with small steel 
'hooks' clearly saying "Please steal me!"so they did.

Fred Sawyer sent me a pic of a French?? dial protected by closing 'clam 
shells??' ( a distant memory and I can't locate the picture).  The ultimate 
deterrent with which I was associated protects my Jamestown Dial which is 
locked into a stainless steel 'safe' at night.  Pic on request.

Frank is right of course in that nothing will deter the ultra-determined thief 
or vandal but, if security is built into the design, theft is unlikely in my 
experience.  Plastic replaceable plates and a ball-pen gnomon don't quite have 
the aesthetic/romantic appeal which brought me to the craft although I did once 
design a bronze  analemmatic memorial dial for a US cemetery which would not 
allow a projecting gnomon.   Viewers are asked to stand a pencil on the current 
date.

Tony Moss




Original Message
From: f...@cl.cam.ac.uk
Date: 17/05/2017 9:03 
To: 
Cc: 
Subj: Re: Mounting Sundials...securely

Dear Roderick,

Bill Gottesman notes the Tony Moss method of
securing sundials to pedestals.

This certainly works but it doesn't stop
anyone with a hammer and a cold chisel
doing serious damage in an attempt to
steal the sundial.

Now take a look at this:

http://www.edp24.co.uk/news/keep-your-eyes-peeled-plea-after-antique-sundial-st
olen-from-blickling-hall-near-aylsham-1-3319691

You will see two photographs taken in
the grounds of Blickling Hall, U.K.

The first photograph shows a damaged
pedestal but with the dial plate still
in position.  This dial was secured in
a Tony Moss fashion and the thieves
damaged the pedestal but failed to
take the sundial.

The second photograph shows what
happened next.  The thieves simply
walked off with the entire pedestal.

The pedestal was 18th century and
had a much higher value than the
sundial (a modern replacement).

It would have been much better to
have had a simple lift-off sundial
and thereby saved the pedestal.

   OK, so what do you do?

I have come to the view that
sundials on pedestals or plinths
in public places are simply too
vulnerable to countenance.  You
either settle for an analemmatic
sundial on the ground or you have
a wall dial sufficiently high up
that it is hard to get at.

   BUT there is a third way...

You have a plinth and you want
a sundial.  I would have a nice
design which was printed on
vinyl and stuck to a prepared
surface on the plinth.  The
replacement cost is about $5
and the scrap value is zero.

   What about the gnomon?

You design the dial for a rod
gnomon but don't actually
provide a rod.  You drill
a hole through the Vinyl and
the supporting brickwork and
arrange for it to be polar
oriented.

You insert a simple piece of
hollow studding and invite
users to put a ball-pint pen
in the hole.

Vinyl is commonly used for
advertisements on buses and
seems to tolerate wind, rain,
snow, ice and loose stones.
The design life is about five
years, or longer than the mean
time between thefts!

Your next challenge will be
that someone will steal the
plaque but let's deal with
one problem at a time.

Frank King
Cambridge, U.K.

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