Sundials

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Gerald Jenkins
Magdalen Bear
A collection of working models to cut-out and
glue together
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A collection of working models to cut-out and
glue together
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Horizontal Sundial - 1
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Horizontal Sundial

• Horizontal sundials
• are probably the most
• commonly seen because they
• so often make
• interesting features
• in parks and gardens.

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Horizontal Sundial

• The gnomon must point
• to the celestial pole
• and therefore
• must make
• the angle of latitude
• with the horizontal.

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Two-Sided Equatorial - 2
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Two-Sided Equatorial

• When set for your latitude and placed on a
  horizontal surface facing north, the gnomon
  points to the celestial pole. The receiving
  surface with the scale on it is then parallel to
  the equatorial plane.

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Three in One - 3
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Three in One

• Sundials on public buildings
• are often of the vertical type
• because they can
• be seen and admired,
• but are not easily reached and
• 'improved' by idle hands.

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Sunbeam Equatorial Sundial - 5
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Sunbeam Equatorial Sundial

• This sundial simulates the Earth,
• with its axis and equatorial
• plane. However, instead of a
• solid gnomon casting a shadow,
• there is a slit gnomon casting a
• beam of light.

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Solar Compass - 8
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Solar Compass

• A solar compass
• is a kind of
• universal horizontal
• Sundial
• used in reverse.

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Solar Compass

• By setting it
• to the local sun-time
• at your latitude,
• you can find north.

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Polar Sundial - 9
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Polar Sundials

• The scale plane
• of a polar sundial
• is parallel to the Earth's axis
• and when it is in use
• the upper and lower edges are
• east-west.

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Time Cylinder - 10

• To find the time
• around the world

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Suntracker - 11
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Suntracker

• The suntracker is not a sundial
• and it does not tell the time,
• but it provides
• an interesting way of
• investigating the path of the Sun
• as it crosses the sky each day.

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Suntracker

• It is very dangerous
• to look directly at the Sun
• and the suntracker allows you
• to measure its
• angle of elevation and bearing very easily
• and with complete safety.

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Nocturnal - 14
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The Nocturnal

• This device makes use of
• three bright stars
• in the northern hemisphere
• to tell the time at night.

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The Nocturnal

• Because the Pole Star
• seems to remain fixed
• and to act as the hub around
• which all the other stars turn,
• we can use it as the Center of a
• giant celestial clock.

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Thats all folks!
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A collection of working models to cut-out and
glue together
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Sunrise sequence every 5 minutes on Feb 7, 2003
Explore the Universe 2004 page 100
www.astronomy.com