The Sundial is a device that tells time by using a flat surface and a long stick called a gnomon to turn the sun's reflection into a shadow that corresponds to a particular marking. The sundial was once used by many civilizations, including the likes of the Ancient Egyptians, the Babylonians, the Ancient Greeks, the Roman Empire, the Chinese, the Mayans, and the European countries during the Renaissance.
- 5000-1500 BC: The first device to tell time was made; the simple model consisted of a pillar sprouting from the ground, similar to the later models of the sundial. Shadow clocks were also developed by Egyptian and Babylonian astronomers.
- 800 BC: The earliest known sundial preserved came from this time period. The model had a base with six different time divisions inscribed, and a raised crosspiece that casted a shadow pointing to a division.
- 560 BC: The Ancient Greeks develop the basic principles of the sundial, derived originally from Babylonian ideas. Since the Greeks founded geometry as well as the concept of conic sections, sundial construction came natural to them.
- 400 BC: The Ancient Greeks begin using the water clock, which measures time by the outflow of water from a particular location..
- 300 BC: Babylonian priest Berossus creates a sundial in the form of a half sphere cut into a large block. A small bead was placed at the center of the half sphere, and its shadow would move in a circular arc throughout the day. The arc was divided into 12 parts, each representing a different hour.
- 263 BC: Around this time the sundial assumed the role as a constant unit of time. The first sundial was also imported to Rome from Sicily.
- 100 BC: Astronomer Theodosius of Bithynia invents a universal sundial that can be used anywhere on Earth, regardless of its position relative to the sun.
- 30-25 BC: Roman author Vitruvius outlines 13 different styles of the sundial.
- 10 BC: The Romans build a very large sundial and call it the Solarium Augusti.
- 150 AD: The Greeks use trigonometry to plot hours with a slanted gnomon.
- 1200: Equal hours of the day are introduced relative to the sundial.
- 1500-1800: Due in part to the spark of the Renaissance, European sundials become extremely popular as the main time-telling device.
- 1700s AD: Clocks and watches begin to replace sundials since they do not require sunlight, but they are frequently inaccurate and must depend on sundials for exact times.
- 1724: The Prince of Dials is placed in Old Delhi, it was the largest sundial in the world at the time. The sundial was so big that the shadow moved at a rate of five feet per minute.
- 1777: French General Lafayette gives General and eventual President George Washington a silver Explorer Sundial as a gift of respect.
- Early 1800s: Mechanical clocks become accurate and inexpensive enough to begin replacing sundials.
How the Sundial Works