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Sundials: The Science and History

Kashmira Lad
Sundials are the oldest devices used to measure time. It is interesting to think of how people relied upon the position of the sun to know the accurate hour of the day.
A look at the various brands in the market will reveal the variety of wrist watches and clocks available. From sophisticated to funky, timepieces have become more of a fashion statement than an utility now.
Though mobile phones have immensely decreased the use of wrist watches, they are still a collectors pride. Let's find out the strategy used by our ancestors before the age of wrist watches and digital analogs.
The oldest device used to measure time is the sundial. This ancient instrument based on the scientific calculations, is solely based on the position of the sun. A sundial can be seen in various types of designs. The time is measured as per the shadow of the sun.
The shadow is cast on the surface of the dial by a straight and sharp panel that is placed in the center of the dial. Around this panel are lines that indicate the hours of the day. This is apparent only when the shadow of the sun falls on the particular line.
As the position of the sun changes during the day, so does the shadow of the sun cast by the sharp panel. The direction of the panel should always point to the true North and not at the magnetic North Pole of the earth. Only then can one know the correct time of the day. The True North refers to the geographic North Pole.
It is believed that the invention of the sundial dates back to 1500 BC. However, historians are still unsure when and where was it actually invented. Some reports reveal that it may have been in areas of the Middle East and the credit is given to the Sumerians, while some speculate sundials were also common in countries of the Far East.
Sundials have been present in various civilizations for many years altogether. In Egypt, historians have noted the use of an obelisk, a tall structure that served as a sundial. These were placed in various locations in Egypt. Archaeologists have also discovered the use of stone sundials, which were flat, and 12 inches in length.
The Greeks and the Romans were known to develop sophisticated versions of the sundials. Portable dials were particularly noticed being used by the Romans. There were more elaborate designs seen during the Medieval and the Renaissance period. They can be thus divided into two categories, Altitude and Azimuth.
Altitude sundials refer to the time that is determined from the height of the sun above the horizon. Therefore, the dial has to be aligned to the sun. Azimuth dials show the time as per the angle of the sun.
Historians have noted the years between 1500 and 1800 AD to be the greatest period in the history of sundials. This was also the time when great astronomers such as Giovanni Padovani and Giuseppe Biancani revealed about constructing the perfect sundial in their scholarly articles and thesis.
In the earlier times, not everybody could afford to have a sundial. The people then, had to refer to sundials that were placed around in the city mounted on public buildings.
Today, there are still many who prefer to collect sundials despite the modern form of wrist watches available in stores. Perhaps, it is the beauty of the mechanism that sets it apart and makes it a unique instrument to own.