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Science, Maths & Technology

Clock Glossary

Updated Monday 28th January 2008

Glossary of terms relating to clocks and sundials, part of the BBC/OU's programme website for Rough Science 2

Clockwise direction - The same direction as hands on a clock.

Shortest - If you are in the tropics you may even notice that the shadow disappears at noon because the sun is directly overhead.

Shadow stick - The technical name for a shadow stick is gnomon, pronounced "No mon", and is Greek for "the one who knows".

Latitude is a measure of north-south position on the globe. It is described as the angle between a position on the globe and the equator. At the equator latitude is 0o, whereas at the poles it is 90o North or 90o South. On a map these are shown as horizontal hoops around the Earth.

Equinoctial - Sometimes known as equatorial.

Mean solar time - The time used in the modern clock.

Water clock - For many centuries, the best technology available for keeping time was the water clock. While these clocks weren't always reliable they worked indoors, at night and on cloudy days, so in many ways they were more useful than the sundial, the only other clock in use at the time.


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