"F B" wrote in message ...
Hi all

If you are interested by constructing your own sundial, you may be
interested by the web site www.shadowspro.com

It provides a freeware program to calculate plane sundials (any orientation
and inclination), analemmatic sundials and cylindrical sundals. They can be
built for any place in the world, including the southern hemisphere.
Sundials are printed full scale with all data needed to create a real
sundial. It is really simple to use.

In addition, you can simulate the shadow path on your sundial for a given
instant or in an animation. An astronomical ephemeris is also provided.

This program is provided in 8 languages, English, French, German, Italian,
Spanish, Portuguese, Dutch, Hungarian and comes with an extensive HTML
online help.

Come and visit the web site to see screen captures and view the list of
functions; and download the program.

Thanks
FB


Perhaps you can explain to participants here that it is necessary to
define the 24 hour day first via the axial rotation of the Earth and
this preceded the determination of the sidereal day by Flamsteed and
Huygens.You cannot figure out the sidereal value without first
defining a 24 hour clock day and somehow in the beginning of the 21 st
century,men have got lost as to what the Equation of Time does in
bridging the gap between the natural unequal day and the 24 hour clock
day.

You will find nobody here with the exception of myself who will agree
with you,those who maintain the axial rotation of the Earth through
360 degrees is 23 hours 56 min 04 sec insist that axial rotation is
determined by stellar circumpolar motion rather than the Sun based
reference of sundials,the EoT how the 24 hour clock emerges from the
difference between natural noon and clock noon or the difference
between the natural unequal day and the constant 24 hour clock day by
means of axial rotation.

"The earth makes a complete turn on its axis in 24 hours; it turns
therefore 360° in 24 hours or 15° each hour. If you were to stand on
one of the poles with a flat circular disk divided into sectors of
15°, you would be able to read the hour using the shadow of a vertical
rod placed through the centre of the disk. If you aligned the first
sector with the shadow cast by the Sun at its highest point overhead
at noon --the meridian--, then the shadow would cross the next sector
an hour later, and so on. The sector lines are thus hour lines."