Facts About Sundials And Shadow Clocks
Sundials are in use since ancient times and until the early 19th century were the main indicators of time. At the beginning of the 20th century served only to show the exact time at noon, to adjust until then still insufficiently precise clocks. Sundials are now used only as a decoration on the streets or buildings. If placed in the right way, show up 5 minutes accurately.
The sundial is one of the world’s oldest scientific instruments. Designed to tell the time to the nearest hour, the ancient contraption was first created by the Babylonian and Egyptian civilisations and works by measuring the Sun’s movement across the sky.
The mechanism’s dial is known as a gnomon or style and contains numerals representing the hours of the day, so when a shadow (or shard of light in some variations) is present on a specific number, that is the current hour. Sundials vary by their latitude.
The Sun appears to take various paths across the sky in different parts of the world so a sundial must be tailored for the location it is in. Also, the time shown can vary by how close it is to a time-zone boundary. Clearly, they work better in sunnier areas, so they are more effective in the Mediterranean than in England!
Sundial points north – Sundials need to point north and sit on a flat surface. The gnomon – the part that protrudes from the dial – casts a shadow.
Shadow length – The Sun is highest in the sky at midday and casts short shadows. When it is lower in the sky, shadows are longer.
Obelisk – According to archaeological records, the earliest known sundials are obelisks (3500 BC), and the shading clocks (1500 BC) from ancient Egyptian and Babylonian astronomy.
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