Message text written by John Carmichael
At risk again of exposing my limited math skills, I was wondering if it
would be possible to get an approximation of the area of an elipse by the
following method:
Average the length of the major an minor axises and then apply the formula
for the area of a
resulting
in its recovery.
Patrick Powers
Message text written by Robert Terwilliger
I wonder how the group feels about opening the forum to allow members to
post messages offering items or services for sale, or want lists of
things they might wish to purchase.
If I take my own interests as a guide here I DO think that there will be
None such as you describe in the BSS Register - thought there is are a few
Roman hemispherical dials in Britain. There are two semi-cylindrical stone
scaphe dials on either side of a tombstone in Suffolk UK. They are dated
1725 though. The upper edge of the the scaphe lies on the polar axis
Message text written by John Carmichael
Although I have has a most interesting morning reading about this, I fear
that your questionner is going to be disappointed. One can find (and
astonomers have!) very many periodicities associated with the
earth/moon/sun system. Many of these are very
David Rose asked re polarization dials.
Allan Mills of the Astronomy Group, Leicester University, Leicester, LE1
7RH wrote an article on these in a BSS Bulletin I am sure. However, I
cannot (now) find the reference nor can I tell you if he lurks on this list
- you might try sending an enquiry
Message text written by Sara Schechner
As an alternative approach we could get round this by specifying
the angles of universality. e.g., UNIVERSAL 60°N - 10°S
I would go with this. I don't like the idea of something being 'partly
universal'. It seems to me things are either universal or
Message text written by John Carmichael
I even have a ruler and lined velum drafting paper both graduated in
decimal inches!
In the UK many (if not most) Imperial measure rulers are graduated
somewhere in decimal inches as well as in eighths and sixteenths and they
have been ever since I was
What's all this inches nonsense.
Tsk, Tsk. How could you? !
Patrick
Ken Clark wrote:
My local community is in the planning stages of revitalizing our local
train station. I was thinking, why not include a sundial as part of the
design for the passengers to look at while waiting for the train. I like
vertical declining dials because they are some what
Message text written by Ian Trackman
Underneath the ring is scratched SP 640036
Not sure I can help but SP 640036 is the UK Ordnance Survey Reference for a
point in the UK at N51deg 44min W01deg 04min. This refers to a place
about 6 miles to the East South East of Oxford between Great
Message text written by John Carmichael
then, on the average, if you read the time
directly from a longitudinally corrected dial, your non-EOT corrected
reading would be off by about seven minutes on any day of the year.
That may be the average but the average doesn't have any meaning to the
Message text written by Frank Evans
but for navigators EoT has always been mean time minus apparent
time. My
British Admiralty Manual of Navigation, Volume 2, 1938 states simply:
The equation of time is defined as the excess of mean time over apparent
time.
I have just looked up a
This is a common problem. Historically there have been two ways of
assigning the positive and negative signs to the Equation of Time. It all
depends on the way you think of the difference of the two entities that
give rise to the EoT.
I think (but am not entirely sure) that navigationalists
I would set this value to 25 kB so that e.g. small image can be sent (at
the moment
the value for maxlength is set to 10 MB :-). Would this find agreement?
I would plead for a limit that's just a tad larger - say 40-50kb since, as
I mentioned before, there is a real benefit from having the
Message text written by Malcolm Purves
It sadens me therfore that the only course left to me is to
unsubscribe.
We shall be sorry to lose you. I entirely agree with you when such
attachments are very large. Unfortunately with the ease and smoothness of
e-mail it is easy and frankly often
Message text written by Claude Hartman
It was mentioned that this was done extensively in England
for church windows. Does anyone know of existing examples?
There are more than thirty such dials still in existence in the UK (and
known to the British Sundial Society's Sundial Register) some of
Message text written by David Higgon
why you don't get an eclipse of the sun every month
You are right it is because the earth moon and sun are not in the same
plane but it is also a consequence of the three objects interacting as a
three body problem. The motion of the moon (just as with the
Message text written by Luke Coletti
Has anyone ever seen gnomon defined as such?
No, but the Greeks from the 3rd century BC and later the Romans, used the
term to refer to what we'd now call the gnomon's point rather than its
edge. I suspect that Ptolemy or Vitrvius defined it but cannot
From: Patrick Powers,
To: Charles Gann, INTERNET:[EMAIL PROTECTED]
Date: 15/07/99 16:27 PM
RE: URGENT! Authenticity of dial on ebay.
Message text written by Charles Gann
Assuming the dial to be genuine, I had to wonder, where did the British
have a presence at 28-30 deg N
Message text written by Istituto Nautico ARTIGLIO
So I think that, but it's only my opinion, for gnomon should be (and were
by
ancient astronomers) called only vertical objects (such as obelisks)
casting
the shadow on a horizontal surface.
You may be right - Sharon Gibbs (Greek and Roman
Message text written by Charles - diallist.
I chose as my username diallist. And quite right too!! :-)
Am I right or wrong in thinking that diallist is a proper archaic
spelling?
I would say that 'diallist' is the proper MODERN (British!) spelling. In
the US, following some spelling
Frank:
Hope this helps:
To the Year 2029:
YearAsh Wed Easter
199712 February 30 March
199825 February 12 April
199917 February 4 April
2000 8 March23 April
200l28 February 15 April
2002 13 February31 March
2003 5
Can anyone suggest some interesting sundials to see in London, U.K.?
Hi Achim,
Some I can immediately think of are:
The Equatorial dial in Bromley Civic Centre, The Old Palace
Four dials (Scaphe, Vert S,Vert W and Analemmatic), in the Horniman Museum
sundial trail, Forest Hill London (one may
Further to this subject, I alerted Peter Ransom to the thread and he has
asked me to send on the following references that may prove useful:
Kiely, ER 'Surveying instruments, their history and classroom use' (NCTM
yearbook) New York 1947. I had not seen a copy of this on the market for 10
years,
There is a small mongraph: The Cross Staff - Historical Development and
Modern Use Alan N Stimson and Christopher StJ H Daniel, 26pp published by
Harriet Wynter Ltd 1977. It describes the Cross Staff with extracts from
original English instructions for its use from 1574 and later.
This is
Message text written by Les Cowley
Old syle fortune tellers peered into crystal balls. Maybe there
is a supplier somewhere of fortune telling accessories!
Hmmm, presumably they will have 'foreseen' this demand already and no doubt
are writing to us ;-)
Patrick
John,
Here's another for you, though I am unsure of its accuracy! I was playing
just now with the NASS Dialist's Companion and changing the date and time
to find when their calculation of EoT turns to zero.
For the longitude of Greenwich (and, as it happens, 52 Lat and with other
corrections
Hi Gordon,
The difference in the length of the 24-hr day at different seasons of the
year can amount to as much as 16 min.
I think that they mean this to be a description of the equation of time,
but it looks incorrect to me.
They go on to use this to explain the need for mean time.
Am I
Message text written by Frank Evans
but the real trouble was that the next quarter day, the day the rent was
due, was going to arrive eleven days early, a most unwelcome fact.
Because of that the settlement date was indeed moved from the quarter day
and that is also why in Britain the end of
Message text written by John Carmichael
But I am still working on the text and I have a question. I'd like to say
that my sundials
are heliochronometers. My sundial books state that heliochronometers are
very accurate sundials. But what criteria is used?
I always thought - and I have had
Could this be that in theory the sun sets due west on the equinox (as it
would if the earth had no atmosphere) but in reality is sets slightly south
of due west due to refraction, and would this explain the time delay? This
has really bothered me, because I want my dials to be correct.(my dials
be especially welcome.
Thank you all for your time.
Patrick Powers. BSS Registrar
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John Carmichael wrote:
My customers are thrilled when the find out that they can use their
sundials
at night using the moon, even if it is 45 minutes off. I just thought that
I could narrow down the error with the E.O.T. (they understand the E.O.T.)
and still keeps it simple for the layman.
.
Thanks for your time in reading this.
Patrick Powers, Registrar, British Sundial Society.
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A bit tongue in cheek this because I know absolutely nothing about wood and
its properties for dials.
There is a dial at Downside Abbey (in Somerset, England) which was made a
year or two ago by one of the monks from the wood of an old science
laboratory bench used at the Abbey School!! This
Frank Evans wrote:
The owner is loath to use any modern
materials on it without taking advice, having had earlier bad
experiences of so-called conservation.
I can understand that. You probably know that the BSS has a sub-group
devoted to conservation. It does not adopt the stance (that is
A bit off the refraction topic but Chuck O'Connell expressed interest in
dials that use polarisation. There was an interesting article recently in
one of the BSS Bulletins about using Sellotape as a polarising medium to
make a dial that would indicate hours even when it's cloudy - it uses the
The Register of the BSS has three Tompion dials recorded. Two are at
Hampton Court and one in Bath. All are believed to be genuine.
One of the ones at Hampton Court Palace is the original of the one at Kew
Gardens and the other (a fine dial) had its gnomon broken in the great fire
at the
Thanks to everyone who helped in all this. I have some further information
following a visit to the dial by the original enquirer in heavy rain on
Sunday!
It seems that there is only the second line of the quotation on the dial
and that it is as reported. The dial is interesting in that it has
My second question is rather more mundane. Can any British Sundial
Society members out there remember why the broken hour ring equinoctial
dial was chosen for the symbol of the society. I think it was mentioned
in one of the bulletins, but I can't find it.
It was chosen because the equinoctial
I've asked it at a specialist in Latin... and he answered me back saying
that sentence
is not correct Latin.
He asked to have a closer look ;-)
If possible, could you confirm if there are no 'faults' in the sentence?
Hendrik: Many thanks for replying.
The request for the translation came
I think Alain is correct in interpretating the motto as a warning from
the
dead brothers.
Chris: Many thanks for replying. You have been a great help. I think that
we may be up against faulty Latin as well as an obscure inscription!
I shall try and find out more about the background to the
at the nearby Hall. It has two dial
faces. On the SW face is the inscription:
Carpere vel noli nostra vel ede tua
Despite learning Latin many years ago I am unable to translate this and
have no longer any dictionaries etc. Can anyone help me? It would be much
appreciated.
Patrick Powers
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