Hi, I stuck a tall nail perpendicularly in a horizontal board for the equinox and I marked the position of the shadow of the nail's head several times the day before and the day after the equinox (the equinox was in the middle of the night for California). I got two parallel tracks very close together (which show that my house errs from being east-west by a little over a degree).
Since the sun heads north at about a minute of angle per hour, is the east-westedness of my tracks off by a minute of angle per hour divided by 15 degress per hour or one part in 900 (about 4 minutes of arc)? Can it be that simple? Thanks! John Bercovitz -
