The
George Washington Sundial Our clocks differ from sun time due to 3 effects; two due to our own choices and one due to nature:
The sum of these 3 effects is always positive here in Lexington, so our clocks are always ahead of our
sundials; way ahead during DST. Clocks are ahead by:
Our sundial is a copy of the one George Washington had made for him and placed in the center of the circular courtyard in front of his Mount Vernon home sometime before 1785. The badly worn original dial is now kept inside the house at Mount Vernon but a copy like ours has replaced it in the courtyard. The copies are made of cast bronze in fine detail by Virginia Metalcrafters. Since the latitude of Lexington (38.0o North) is nearly the same as Mount Vernon (38.7o North), the dial designed for George serves very well for us too. The dial, with two-minute tick marks, is readable and accurate to about one minute. Read the time at the edge of the shadow that is cast by the top of the gnomon (the edge of the shadow away from the XII mark). Our dial is in the shadow of the church until around noon. The gnomon makes an angle of 38o from horizontal and points north so it is parallel to the earth's axis. As the earth spins, the gnomon keeps pointing in the same direction - toward the North Star. The streets in downtown Lexington don't run N-S and E-W, they are about 45o off; so our dial appears to be oriented at a diagonal in our courtyard. Our dial is a classical horizontal sundial - as such, it reads solar time instead of clock time. What good is such a timepiece? Think of it as a true natural clock that tells us what time it really is, here where we are, instead of the adjusted time we adopt to accommodate our constant-speed clocks and our wish to synchronize with folks in other places. If you want to know clock time you probably already have that available on your watch anyway. You can check your watch using the sun: just add the amount given above to the sundial reading. This chart shows the separate contributions to the correction for clock time throughout the year:
(For an excellent explanation of the effects of the earth's tilt and elliptical orbit, visit analemma.com.)
After a decade of controversy and confusion, Lexington officially dropped "sun time" and adopted "standard time" ("railroad time") in 1896. Official clocks were set back 22 minutes, putting us on Central Standard Time. Church clocks were often slow to conform, preferring to keep "God's time" instead (and our love of sundials is no doubt a reflection that same feeling). In 1960, Lexington, along with central and eastern Kentucky, switched from Central to Eastern Standard Time ("fast time"). On the fourth day of creation, "God said 'Let there be lights in the dome of the sky to separate the day from the night; and let them be for signs and for seasons and for days and years' ... two great lights ... and the stars." Accordingly, our calendar is related mainly to the motion of the "greater light", the sun. We have dropped most of our calendar's relation to the "lesser light", the moon, except that our months are close to the length of the moon's cycle. Any relation to the stars has practically vanished from our lives. We still base one significant calendar "sign" however on both the sun and the moon: we celebrate Easter on the Sunday after the first full moon after the first day of spring. In 2008, the sun rose directly east on Thursday, March 20, the moon was full the very next day, Friday, March 21, and Sunday followed just two days later, on March 23. See the Calendar So Easter came very early in 2008: March 23. It hasn't been this early since 1913 and won't be this early again until 2160. Easter could possibly come even one day earlier, on a March 22 (when Spring, the full moon, and a Sunday fall on 3 days in a row - March 20, 21 and 22), but that hasn't happened since 1818 and won't happen again until 2285. This Easter is the earliest one most of us get to see!
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