Good Morning - A complex subject of very olde standing which I think may be better illustrated from this web site? http://aa.usno.navy.mil/data/docs/JulianDate.html Hope it helps Cheers - Roy John and Margaret Moore <[email protected]> wrote: What do I do with a date of 29 Feb 1639 OS? This would be in 1640 by the Gregorian calendar we use now, so allowable: the year divides evenly by 4. But if we use the same rule for an OS date, it would have to be interpreted as a clerk's error, probably for 1 March. What was the rule for the Julian calendar? Or did they just not have leap years? Regards, John Moore ==================================== WEB PAGE: http://homepages.rootsweb.com/~oel/ ARCHIVES: http://archiver.rootsweb.com/th/index?list=OLD-ENGLISH ------------------------------- To unsubscribe from the list, please send an email to [email protected] with the word 'unsubscribe' without the quotes in the subject and the body of the message