Sundials have been around since the days of the Sumerians, some five thousand years ago, and were the earliest known means of keeping time. The first sundials were probably just rods or sticks pounded into the ground, and the shadows cast by those vertical rods (called a gnomon) allowed ancient people to know what time of day it was.

The Greeks and Romans took the basic concept and refined it, using various different shapes of dials to not only tell the time of day, but also what time of year it was by the shadow cast by the gnomon into a cleverly designed bowl. As the centuries went by and technological advances made clocks and watches commonplace, sundials were largely relegated to decorative status in gardens.

Sundials Today

As to whether you can actually tell time by using a sundial, that's a bit trickier. Modern clocks and watches assume there are exactly twenty-four hours in a day, but isn't the case, which is why we have to add a 29th day to the month of February every four years.

That may be convenient for modern society, but it means that a sundial, which expresses the true nature of Earth's elliptical orbit around the sun, is sometimes fast and sometimes slow, depending upon the season. Deep in February, for example, a sundial would be about fifteen minutes slow according to modern timepieces. However, in November, a sundial would appear to be as much as seventeen minutes fast. Such deviation could cause serious problems for the modern world, which depends upon accurate, uniform time throughout the globe. (Interestingly, sundials actually are correct on four days of every year, although those dates may vary: April 15, June 14, September 2, and December 25.)

Of course, your sundial must be oriented correctly. The numbers corresponding to the shadow of the gnomon need to be calibrated according to the specific longitude and latitude of your location. There are various sites on the Internet that can help you set your sundial up correctly. There are also sundial enthusiasts around the world who have formed organizations that will be more than happy to help you get your sundial up and running. Just type "sundials" into your browser and you'll find lots of information.

So the question remains: can you really tell time with a sundial? The answer is an unqualified yes--and no--depending upon who you talk to. One thing for sure, sundials dress up your garden. And in the garden, do you really care what time it is?

Copyright (c) 2006 Jeanette J. Fisher