Hi Jack, While following a lead based on Sasch Stevens display at the conference, I came across an interesting article on the Al Khanum dial by Googling "Alexander the Great sundial". This search found this article: "A Unique Greek Sundial Recently Discovered in Central Asia" by Rene Rohr in 1980 in the JRASC. The article describes the work at Al Khanum by Paul Bernard. See http://adsabs.harvard.edu/full/1980JRASC..74..271R Their conclusion is the same as yours, the dial is a an equatorial with a polar gnomon but the lines show temporal hours rather that straightforward equal hours.
Regards, Roger From: Jack Aubert Sent: Sunday, August 02, 2015 6:55 PM To: [email protected] ; [email protected] ; [email protected] ; [email protected] Subject: RE: Temporal Hours I assume that you are referring to the Arachne of the Amphiareion. I have a photocopy of your article on that dial, which was reconstructed from fragments, describing a (very old) horizontal dial with equal hours. Another atypical dial: The Ai Khanum dial found in the ruins of Alexandria on the Oxus (in modern Afghanistan) that dates from approximately 145 BC is an example of a polar-oriented gnomon with unequal hours. This dial is interesting for several reasons, in particular the fact that while it “naturally” told equal hours using the line-shadow of the gnomon, the constructor carefully incised lines to read unequal hours using the gnomon tip. (It was done incorrectly for its latitude, but that’s another story.) However, both these dials are quite exceptional. My general impression from what I have been able to read is that equal hours were used by astronomers and astrologers. While there is at least one example of a horizontal dial that uses equal hours and at least one example of a polar gnomon using temporal hours, people generally wanted their time in temporal hours so the vast majority of surviving dials prior to the Ibn al-Shatir dial used temporal hours. Jack Aubert
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