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Hello David,
I agree with your first statement:
Formulas should be universal and therefore work in
both hemispheres and with East and West longitudes.
The other statemants are arbitrary.
As an example:
In navigation north has 0 degrees azimut, in
gnomonics usualy south.
So we will find several definitions in several
fields.
Also in gnomonics you will find differrent
definitions by different people and even in different countries.
More important to me is to mention the definitions
that are used and that they are consistent to your statement 1.
Therefore I have my definitions listed on my WEB
site as well in my computerprogram Zw2000.
I tried to use the most common in gnomonics and I
choose for EoT the definition with positive value in november.
This last one also is the international definition
by IAU.
The French as an example usualy use the opposite
definition for EoT.
If this is known it is no problem at
all.
It would be ideal if all gnomonists spoke the same
language, but I think this will be a wish for ever.
Best wishes, Fer.
----- Original Message -----
Sent: Wednesday, September 26, 2001 11:15
PM
Subject: RE: EoT
Dear
All,
I have been
puzzling over this for some time.
If we establish
some basic principles for constucting a consistant set of definitions for
sundial constructions (see Fer's page)
e.g.
- Formulas should be universal and therefore
work in both hemispheres and with East and West longitudes.
- When measuring North-South Direction: North is
positive, South is negative.
- When measuring time: Later times are
represented by numbers more positive that the numbers representing earlier
times. Which implies that when measuring East-West direction: West is
positive, East is negative.
- Angular measure and time differences
are measured in degrees. This is done through the convention that 1
day = 1 rotation or 24hours = 360degrees.
Question: Under
these principles which of the two definitions for EOT makes the most
sense?
I have expressed
the opinion that the first (or older) definition is consistant
with the above principles. Now however I wonder if I haven't missed
something?
Regards,
David
-----Original
Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]On Behalf Of fer j. de
vries
Sent: Wednesday, 26 September 2001 3:49 AM
To:
sundial
Subject: EoT
Hello Yvon,
In a Dutch book about
sundials I read that in The Netherlands the definition
of the Eot
was:
EoT = mean time - solar time
This means in november the sign is
negative.
In about 1930 a new and international definition was
accepted.
EoT = solar time - mean time
This means in november the sign
is positive.
During a certain period both definitions were used, even
in the same issue
of a magazin.
After the second worldwar usualy only
the international definition is used.
Best wishes, Fer.
Fer J.
de Vries
[EMAIL PROTECTED]
http://www.iae.nl/users/ferdv/
Eindhoven,
Netherlands
lat. 51:30 N long.
5:30 E
----- Original Message -----
From: Yvon Massé <[EMAIL PROTECTED]>
To: sundial
list <[email protected]>
Sent:
Tuesday, September 25, 2001 12:16 AM
Subject: Equation of
time
> Hello all,
>
> Ooops!...
Of course, I make a mistake:
>
> >For example in
France, traditionally: EoT = real time - mean time
> >while
in USA: Eot = mean time - real time.
>
> Please
read:
> For example in France, traditionally: EoT = local mean
time - solar time
> while in USA: Eot = solar time - local mean
time.
>
>
Yvon
>
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