RE: South Vertical Declining dial
Dear Dave: You have made a simple math time correction error that is causing the larger than expected 10 minute difference between your watch time and your solar sundial time. You wrote: <. The standard time meridian in my area is 120 degrees, me being at 118.1 = equals approximately 4 minutes.. No, that is not correct because you calculated incorrectly the longitudinal shift time correction value The longitudinal shift correction value equals the number of degrees you are away from the Prime Meridian times 4 minutes of time per degree. First, find out how many degrees you are from the Prime Meridian which is: 120*- 118.1*= 1.9* Then multiply 1.9* x 4 min./* = 7.6 min. or 7min 36sec Your longitudinal time shift correction is 7min 36sec, not 4 minutes as you had calculated. In Waugh's book, The equation of time yesterday (I assume you took these readings yesterday, May 14) was 3min 44sec. If you add 7min 36sec + 3min44sec, that equals 10min 80sec or 11min 20 sec. This is much closer to the time difference you observed. This small difference might easily be explained by the method you used to measure you wall declination. Hope this helps John From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, May 14, 2007 4:11 PM To: sundial@uni-koeln.de Cc: [EMAIL PROTECTED] Subject: South Vertical Declining dial Dear Sirs: Here's my problem. When my south vertical declining dial reads 11:00 my watch (set by Click here: The official US time <http://www.time.gov/> ) reads 10:50, when it reads 12:00 my watch reads 11:50 at 2:00 the watch reads 1:50 and at 3:00 the watch reads 2:50. The location of the dial is at 33.44N and 118.1W, the declination of the wall is between .1 degree and 2.7 degrees west of south depending on the accuracy of the measurement. I used two methods one from www.precisionsundials.com/walldeclination.exe which produced the .1 degree and the other from Click here: Sundial <http://www.sundialsculptures.com/index.html> Sculptures by John Carmichael, Jr. which produced 2.7 degree based on the measurements I gave him. John was extremely helpful and even sent dial plate with gnomon measurements. The times above were taken on 5/13/07. The standard time meridian in my area is 120 degrees, me being at 118.1 = equals approximately 4 minutes and the EOT on the 13th is 3:44 (from table A.1 in Sundials - Their Theory and Construction, by Albert E Waugh, that's still only adds up to 7:44. If this is the wrong forum for this kind of problem please let me know, any and all help is appreciated. Thanks Dave Koller <http://www.time.gov/> _ See what's free at AOL.com <http://www.aol.com?ncid=AOLAOF0002000503> . --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: South Vertical Declining dial
Dear Dave, Your calculations are close, but being 1.9 degrees east of your meridian, this makes your dial run fast by 7 minutes, 36 seconds, not including the equation of time. Each degree of longitude from the meridian affects the dial by 4 minutes. So, your dial should be 7' 36" fast by your location, plus 3' 44" fast for what you give as the EoT, for a total of 11' 20" fast on may 13. If your dial is accurately made, and you are able to read the sundial time to within a few seconds (you may be able to do this if you know how to use a shadow sharpener), you can calculate how "misaligned" your dial or wall is using www.precisionsundials.com/sundialalign.exe . It works best near the solstices, so next month would be the ideal time to try it out. Bill Gottesman www.precisionsundials.com - Original Message - From: [EMAIL PROTECTED] To: sundial@uni-koeln.de Cc: [EMAIL PROTECTED] Sent: Monday, May 14, 2007 7:10 PM Subject: South Vertical Declining dial Dear Sirs: Here's my problem. When my south vertical declining dial reads 11:00 my watch (set by Click here: The official US time ) reads 10:50, when it reads 12:00 my watch reads 11:50 at 2:00 the watch reads 1:50 and at 3:00 the watch reads 2:50. The location of the dial is at 33.44N and 118.1W, the declination of the wall is between .1 degree and 2.7 degrees west of south depending on the accuracy of the measurement. I used two methods one from www.precisionsundials.com/walldeclination.exe which produced the .1 degree and the other from Click here: Sundial Sculptures by John Carmichael, Jr. which produced 2.7 degree based on the measurements I gave him. John was extremely helpful and even sent dial plate with gnomon measurements. The times above were taken on 5/13/07. The standard time meridian in my area is 120 degrees, me being at 118.1 = equals approximately 4 minutes and the EOT on the 13th is 3:44 (from table A.1 in Sundials - Their Theory and Construction, by Albert E Waugh, that's still only adds up to 7:44. If this is the wrong forum for this kind of problem please let me know, any and all help is appreciated. Thanks Dave Koller -- See what's free at AOL.com. -- --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
South Vertical Declining dial
Dear Sirs: Here's my problem. When my south vertical declining dial reads 11:00 my watch (set by _Click here: The official US time_ (http://www.time.gov/) ) reads 10:50, when it reads 12:00 my watch reads 11:50 at 2:00 the watch reads 1:50 and at 3:00 the watch reads 2:50. The location of the dial is at 33.44N and 118.1W, the declination of the wall is between .1 degree and 2.7 degrees west of south depending on the accuracy of the measurement. I used two methods one from _www.precisionsundials.com/walldeclination.exe_ (http://www.precisionsundials.com/walldeclination.exe) which produced the .1 degree and the other from _Click here: Sundial Sculptures by John Carmichael, Jr._ (http://www.sundialsculptures.com/index.html) which produced 2.7 degree based on the measurements I gave him. John was extremely helpful and even sent dial plate with gnomon measurements. The times above were taken on 5/13/07. The standard time meridian in my area is 120 degrees, me being at 118.1 = equals approximately 4 minutes and the EOT on the 13th is 3:44 (from table A.1 in Sundials - Their Theory and Construction, by Albert E Waugh, that's still only adds up to 7:44. If this is the wrong forum for this kind of problem please let me know, any and all help is appreciated. Thanks Dave Koller (http://www.time.gov/) ** See what's free at http://www.aol.com. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
