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Dom and Lauras Sundial presentaionPresentation Transcript
What is a Sundial?• A Sundial is a common instrument used to tell the time. As you can see in the name the instrument uses the sun. They show the time by a shadow of a pointer casted by the sun onto a ﬂat surface indicating the hours of the day on it.
How does a Sundial Work?• A Sundial works by a gnomon which is an essence on any form of stick. The gnomon casts the shadow and determines the solar time at that moment.• As you can see by the name, a sundial is a instrument that measures the time using the sun. As the sun moves across the sky so does the gnomon, it moves towards the diﬀerent hours at the speed of the sun. Every design of a Sundial relies on the gnomon, without the gnomon the sundial won’t be able to progressively move from hour to hour.
Who uses Sundials?Sundials are used all over the world,therefore the ﬁrst evidence of a Sundialexisting was in the Roman, Greek,Babylonian and Egyptiancivilisations . They were known to be themost accurate time readers in thosehotter areas of the world, so peopletended to use them more that otherclocks. The oldest sundial wasapparently developed in Greece inaround 340BC, so the Sundial was madeand used by a lot of people in that timeframe.
Summary• A Sundial is a common instrument used to tell the time. A Sundial works by a gnomon which is an essence on any form of stick. The gnomon casts the shadow and determines the solar time at that moment. They are found all over the world.