The sundial is an ancient method of timekeeping. The Egyptians were the first group of people that we have hard evidence that saw keeping time as important. Some experts believe that the Sumerians had timekeeping methods thousands of years before the Egyptians, but the proof for this theory is purely speculative.
A sundial works by following the movement of the sun around the earth's celestial pole by casting a shadow or a point of light on a surface that is marked with hour and minute lines. The shadow-casting device, which is called the gnomon or the style, must point towards the north celestial pole, which is very close to Polaris, also known as the North Star. The gnomon serves as an axis around which the sun seems to rotate.
The thinner the shadow line is, the greater the accuracy of the sundial. In other words, the larger the sundial is, the greater its accuracy will be. This is due to the fact that the hour line is capable of being divided into smaller portions of time.
However, if the sundial gets too large, a point of diminishing returns will be reached. This happens because, due to the diffraction of light waves and the width of the sun's face, the shadow will spread out and become fuzzy. This diffraction makes the sundial quite difficult to read.
Beginning in 3500 B.C., the Egyptians started to build tall four-sided tapered monuments, which were called obelisks. They constructed them in strategic locations in order for them to cast shadows from the sun. The moving shadows formed a kind of sundial which indicated midday, allowing the Egyptians to divide their day in two different parts.
These obelisks also designated the shortest and longest day of the year by the length of the shadows they cast. Later on, they added indicators around the base of the monument to show further time subdivisions.
Next, around 1500 B.C., the Egyptians further advanced the design of the sundial by producing a more accurate shadow clock. This sundial was partitioned into ten sections, which also included two twilight hours.
This sundial was only able to keep accurate time (by today's standards) for half of the day. Because of this characteristic, the device needed to be turned 180 degrees around noon in order to measure the afternoon hours.
Throughout the years, sundials evolved from flat horizontal or vertical plates to more complex forms. These changes were driven by the search for greater accuracy.
One new version was the hemispherical dial, which was a bowl-shaped depression cut into a block of stone. It contained a central vertical gnomon and was scribed with different sets of hour lines for each season.
This sundial evolved into the hemicycle, which most scholars believe to have been invented around 300 B.C. The hemicycle removed the unnecessary half of the hemisphere, which gave it the appearance of a half-bowl cut into the edge of a squared block.
Throughout time, the sundial has evolved and changed to more accurately tell the time. Today, however, with modern timekeeping technology, the need for a sundial has completely diminished. However, they still make an attractive addition to any backyard, mostly for decorative purposes.
A sundial works by following the movement of the sun around the earth's celestial pole by casting a shadow or a point of light on a surface that is marked with hour and minute lines. The shadow-casting device, which is called the gnomon or the style, must point towards the north celestial pole, which is very close to Polaris, also known as the North Star. The gnomon serves as an axis around which the sun seems to rotate.
The thinner the shadow line is, the greater the accuracy of the sundial. In other words, the larger the sundial is, the greater its accuracy will be. This is due to the fact that the hour line is capable of being divided into smaller portions of time.
However, if the sundial gets too large, a point of diminishing returns will be reached. This happens because, due to the diffraction of light waves and the width of the sun's face, the shadow will spread out and become fuzzy. This diffraction makes the sundial quite difficult to read.
Beginning in 3500 B.C., the Egyptians started to build tall four-sided tapered monuments, which were called obelisks. They constructed them in strategic locations in order for them to cast shadows from the sun. The moving shadows formed a kind of sundial which indicated midday, allowing the Egyptians to divide their day in two different parts.
These obelisks also designated the shortest and longest day of the year by the length of the shadows they cast. Later on, they added indicators around the base of the monument to show further time subdivisions.
Next, around 1500 B.C., the Egyptians further advanced the design of the sundial by producing a more accurate shadow clock. This sundial was partitioned into ten sections, which also included two twilight hours.
This sundial was only able to keep accurate time (by today's standards) for half of the day. Because of this characteristic, the device needed to be turned 180 degrees around noon in order to measure the afternoon hours.
Throughout the years, sundials evolved from flat horizontal or vertical plates to more complex forms. These changes were driven by the search for greater accuracy.
One new version was the hemispherical dial, which was a bowl-shaped depression cut into a block of stone. It contained a central vertical gnomon and was scribed with different sets of hour lines for each season.
This sundial evolved into the hemicycle, which most scholars believe to have been invented around 300 B.C. The hemicycle removed the unnecessary half of the hemisphere, which gave it the appearance of a half-bowl cut into the edge of a squared block.
Throughout time, the sundial has evolved and changed to more accurately tell the time. Today, however, with modern timekeeping technology, the need for a sundial has completely diminished. However, they still make an attractive addition to any backyard, mostly for decorative purposes.