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How to Set an Armillary Sundial

Updated February 21, 2017

Garden armillary sundials--modelled in design after old astronomical instruments--like flat sundials act as clocks that use shadows to show the approximate time during the day based on the movement of the sun as it progresses across the sky. Armillary sundials feature an arrow-shaped stationary indicator (gnomon) that, when pointed in the correct direction, casts a shadow across a band on the sundial that contains numbers corresponding to the hours of the day. When set correctly, an armillary sundial provides a garden with a beautiful accent that also marks the passage of time.

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Select a flat area of your garden that receives direct sunlight all day. Place your armillary sundial on a stable pedestal or table in this area.

Locate north on your compass and point the gnomon's arrowhead in that direction.

Set your watch to the local time and at the top of a morning hour, move the hour band so that the edge of the gnomon's shadow falls across the matching number on the band. Check you sundial again at the top of the hour later in the day. If the edge of the sundial's shadow falls nowhere near the correct number, check your compass reading and readjust the gnomon and hour band as needed. If the time is off slightly by about 15 minutes, don't worry--sundials only show the approximate time. Many things can affect this reading, such as the speed up and slow down of the earth's orbit around the sun.

Mount your sundial. Secure it to the surface with whatever material you choose. For example, glue it to the surface with cement or weatherproof adhesive; or screw it into place.

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Things You'll Need

  • Pedestal or table
  • Compass
  • Weatherproof adhesive or cement (optional)
  • Screws (optional)

About the Author

Based in Southern Pennsylvania, Irene A. Blake has been writing on a wide range of topics for over a decade. Her work has appeared in projects by The National Network for Artist Placement, the-phone-book Limited and GateHouse Media. She holds a Bachelor of Arts in English from Shippensburg University.

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