Hello Sandy, Yes, you can shift the scale on the equatorial ring of an armillary sphere to correct for longitude and daylight savings time. The correction is linear. An example is shown on my website http://www3.telus.net/public/rtbailey/images as "Roger's Armillary.jpg" It is a poor scan of the original slide but you can see the displacement of the scale and an analemmatic noon mark to correct for EOT. I made this one 30 years ago from stainless steel pipe sections. At this longitude 81ยบ24' the sun arrives 25:26 later than longitude 75, the eastern time zone meridian. So at noon when the sun is due south the dial will read 11:34:34 standard time, 12:34:34 daylight savings time. Yours is the same but the correction goes the other way. Your solar noon is at 12:16:00 standard or 13:16:00 daylight.
For further information on armillary spheres have a look at my presentation "Armillary Spheres.pdf" at my main website http://www.walkingshadow.info/Publications/Index.html number 12 on the list. Regards, Roger Bailey Walking Shadow Designs ----- Original Message ----- From: "sandy macleod" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, February 18, 2008 3:31 PM Subject: Armillary dial > > Hi > > I am making an armillary sundial for the northern hemisphere and I had a > question in regards to how to adjust for different longitudes. The > longitude where the sundial is going to be is 71 degrees. Can I > permanently fix the calibration of the dial plate 4 degrees > counterclockwise allowing only the application of the equation of time to > accurately tell time? Also this dial will be primarily seen during > Daylight savings time. Can I fix the dial plate with the 1 oclock line on > the meridian to compensate for daylight savings time? I hope my questions > make sense. > > Thanks in advance > Sandy > _________________________________________________________________ > Connect and share in new ways with Windows Live. > http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_012008 > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
