|
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
>
|
