RE: Is it possible to determine when the sun is due East & West?

Sat, 17 Sep 2005 20:30:03 -0400 (EDT)

Friends,
 
David Lawrence started with the thread about finding east or west for the Muslims.
I should say: use a magnetic compass.
I think this also was done in practice as was done with portable sundials.
 
But isn't the direction to Mecca of more importance? (Qibla)
Then use e.g. a "Mecca map".
 
Not so long ago, 1989 and 1995, two of such 17th century Mecca maps were found.
In one of them a magnetic compass still was there.
This is a moderen drawing of such a map.
In the centre is Mecca at latitude 21 N, longitude 0.
In this case the world meridian is at Mecca, not at Greenwich but that doesn't matter.
This map is for latitued 0 - 50 N and longitude 50 E to 50 W, relative to Mecca.
In the map you choose your place as far as the map is drawn.
A ruler through the centre and your place gives the azimuth to Mecca.
If the ruler has an distance scale also you read how far you are from Mecca.
 
Literature:  

'NRC Handelsblad, 8 january 2000 ( Dutch newspaper ), article by Dirk van Delft

'World-Maps For finding the Direction And Distance To Mecca

'Book by David A. King, ISBN 90 04 11367 3

'Bulletin of "De Zonnewijzerkring", may 2000, article by A.J.M. van den Beld

Also on astrolabes and sundials we find sometimes the line (azimuth) for the qibla.
 
 
This is one part of the play.
 
Another part is the time when to pray.
 
Also prayerlines are found on astrolabes and sundials.
Some can be calculated with ZW2000.
These prayer lines (in ZW2000) are based on the length of the noon shadow of a gnomon plus 0.25, 1 or 2 times the length of the gnomon.
So in practice you could measure the length of the noon shadow and then wait until the length of the shadow is increased with the amount of  0.25, 1 or 2 times the length of the gnomon.
 
I have a Deltacad macro to draw the Mecca map as in this mail.
If you want to draw your own map mail me for that macro.
 
Best wishes, Fer.
 
Fer J. de Vries
 
 
Eindhoven, Netherlands
lat.  51:30 N      long.  5:30 E
Related: :Macintosh HD:Mekka-kaart.gif:0015B485:6B1C767B:00000000:00000000

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