I think there's a simpler solution.
In the UK at noon the shadow of the style on a horizontal sundial faces
North - away from the sun. Turn the style through 180 degrees in a
horizontal plane, and its shadow at noon will face South - towards the sun!
John Lynes
On Mon, 11 Mar 2024 at 17:12, Bill
os Angeles, in the
journal *Illuminating Engineering. * I don't have the reference handy.
John Lynes
On Wed, 26 Oct 2022 at 01:46, John Pickard wrote:
> Good morning,
>
> Has anyone come across this dial-related device?
>
>
> https://picclick.co.uk/ARCHITECT-TOOL-Window-SUNLIGHT-SUN-
fin to show the percentage of window
shielded from direct sunlight at different times of day or at different
seasons.
7. ... and I'm told that sundials have also been used for telling the
time ... ...
John Lynes
---
https://lists.uni
take-home conclusion is
that there is no single ideal reflectance for the plate of a sundial. It
varies with the sky illuminance. When Weber's Law prevails, a reflectance
of about 60 per cent is likely to be a safe bet.
John Lynes
PS I'm away from my computer for the coming week, so will be out of touch
for some t
rply.
Note however that the maximum sky illuminance considered by the authors was
1000 lumens per square foot (corresponding to a solar altitude of about 20
degrees). Higher illuminances might further reduce the optimum reflectance.
John Lynes
On 26 February 2017 at 02:25, Michael Ossipoff
Shadow will be longest to the north at midnight, twice a year, at any point
north of the Arctic Circle.
John Lynes
On 28 October 2016 at 07:58, Frank King <f...@cl.cam.ac.uk> wrote:
>
>
> Where on the planet would you have to
> be, and at what time of year, for these
>
Depressed?
John Lynes
On 27 October 2016 at 23:12, John Pickard <john.pick...@bigpond.com> wrote:
> Good morning,
>
> As part of my research on wire strainers (tools used to tighten wire in
> fences) I am struggling with trying to find some generic terms to describe
>
away from the sun and at an altitude
roughly equal to (90 degrees minus the solar altitude).
These patterns are clearly visible to the naked eye.
John Lynes
On 29 August 2016 at 13:37, Dan-George Uza <cerculdest...@gmail.com> wrote:
> Hello!
>
> I've recently become interested in f
My guess would be a north-facing wall on the Arctic Circle at the summer
solstice, or a south-facing wall on the Antarctic circle at the summer
solstice down under.
John Lynes
On 14 June 2016 at 16:39, Frank King <f...@cl.cam.ac.uk> wrote:
> Dear Willy and Geoff,
>
&g
of sunlight on 21
March. Alternatively at least half the area should receive at least 2
hours of sunlight on 21 March.
There is lots more small print, but these are the principal provisions. I
hope you will share your eventual conclusions with the sundial mailing list.
John Lynes
On 3 June 2014
, not ordinary paper. The Meteorological Office specification lays
down that their length must not change by more than 0.01 inch after
immersion in water for 18 hours, and must not contract by more than 1 per
cent on redrying.
John Lynes
On 19 April 2014 00:27, Brooke Clarke bro...@pacific.net wrote:
Hi
of the same facade.
Danti was expelled from Florence before these meridians could be brought into
regular use.
John Lynes
From: Roger Bailey rtbai...@telus.net
To: sundial@uni-koeln.de
Sent: Sunday, 6 May 2012, 5:12
Subject: Re: Meridian in Siena, Florence
I
eventually let me through
to photograph the meridian, so it's worth persisting.
I wasn't able to discover the 13th century sundial on the Ponte Vecchio. I
hope you have better luck!
John Lynes
From: Richard ghswen...@aol.com
To: sundial@uni-koeln.de
Sent: Friday, 4
that the relative humidity in
the gap is the same as the relative humidity in the outdoor air. Block the
passage with gauze to prevent the entry of insects or dirt.
The double glazing should then become clear. Its thermal insulation would
barely be affected. Worth trying?
John Lynes
,
crossing each longitude once every 24 hours.
John Lynes
From: John Carmichael jlcarmich...@comcast.net
To: 'Sundial List' sundial@uni-koeln.de
Sent: Tuesday, 6 September 2011, 19:08
Subject: Walking Shadow Riddle
A Riddle:
I was watching a dumb movie last weekend and there was a bit of dialogue
.
Aswan is actually about forty miles north of the Tropic, and is not precisely
on the same meridian as Alexandria. Still, like you, Eratosthenes was a genius!
John Lynes
Dear Jackie,
You are right...
I seem to remember hearing about a sun well
... The sun only shone right down it at midday
when
) called a slave-driver.
I also encouraged students to note the height of their belly-button in relation
to a metre rule. They could then mark the height of a vertical wall with
reasonable confidence.
John Lynes
From: Tony Moss t...@lindisun.demon.co.uk
To: sundial@uni-koeln.de
Sent: Thursday
on the analemmatic dial. I leave it to the
heavyweights to recalculate the hourly markings on the dial face.
Alas the gnomon is no longer human, but the device would be interactive,
instructive and, I daresay, unprecedented.
Apologies for a disgracefully late entry!
John Lynes
-Original Message
will already be familiar with it: a flat sundial is essentially a gnomonic
projection of the sky hemisphere.
John Lynes
Lat 51 deg. Long 0 deg.
John Carmichael [EMAIL PROTECTED] wrote:
st1\:*{behavior:url(#default#ieooui) } It would be
useful if there were an easy
Sorry I can't remember where this one comes from:
Lux dei vitae viam monstrat
Sed umbra horam atque fidem docet
(The light of God showeth the way of life,
But the shadow both telleth the hour and teacheth the faith).
John Lynes
P.O.Box 126, Hebron, West Bank, Israel/Palestine.
-
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