Talk:Diptych

message: It would seem to me that we can determine which direction north is only if we know the correct time.  If we know which way north is, we can determine the time... but if either of those variables isn't pinned down we won't have a clue.  Direction and Time are two sides of the same problem, and if one isn't defined we'll never figure out the other.
That would probably explain the compass on later versions of the diptych.  I can't imagine adding one to a device that is already complete without it.
That having been said, I suggest we get rid of the comment about finding north, or at least ammend it to say "if the current time is known, by aligning the shadow to the current time, North can be found".
My guess is a traveller using a diptych would have to mark their heading against Polaris at night, orient themselves at dawn and sunset and pick a landmark, or ask locals which direction north was in order to use the time-keeping functionality of their diptych.  That having been said, I intend to build one for myself and attempt to use it for a while.
:I believe that it would have been general knowledge of how to find North as this may have been more important in earlier times when these diptyches were in use. For example in the 'build a sundial' workshop I run for young people I always point out: 
Buildings:
In Christian countries graves were dug on an East – West line with the Headstone west, this rule is not followed so much now, so look for older graves. Churches were also built on the same lines, with the alter at the East, and the main entrance West facing.
This is but one specific example in the sheet of information they are given, there are four ways of finding North taken contemporary publications. Edmund Patrick ( confer  work) 19:09, 21 September 2007 (UTC)
thread_title:  Determining direction... 

message: It seems to me that this page should either be only about folding thingies in general, or needs a separate section for the sundial. In either case, there ought to be as little redundancy as possible between sundial and here. --Belg4mit 00:09, 11 March 2007 (UTC)
thread_title:  Merge? 

message: I removed substantial text in the sundial portion which was patently false or misleading.  A diptych consisting of a horizontal and vertical sundial will read the same time regardless of orientation, and I gave credible citations which say so.  There do exist diptychs which are self aligning with the use of an analemmatic dial on the horizontal surface.  These would still require knowledge of the date to adjust the gnomon on the analemmatic dial.  The original image was not even a diptych in the sense of the sundial portion of the article, it was merely a portable horizontal sundial with a table of latitudes at the top.
Regarding the text in the unsigned comments above: the dial at www.metmuseum.org would have had little gnomons placed in the empty holes above and in front of the dials to indicate date on the pelekinons.  None of the links show-self aligning diptych dials.--Ron E (talk) 02:12, 20 January 2008 (UTC)
thread_title:  Factual accuracy 

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thread_title:  External links modified