How to Build a Sundial

For centuries, man has used the sun to help him determine the passage of time. Sundials are the most ancient form of time telling devices in the world. You can build a sundial at home and participate in this timeless experience of harnessing nature's clock.

Difficulty:

Moderately Easy

Instructions

Things You'll Need

• Card stock
• Compass
• Magnetic compass
• Board or other flat surface
• Balsa wood
• Level
• Scissors
• Straight edge
• Map
• Paper
• Protractor

Build a Sundial

1. Determine what the latitude is for the place where you live. You can do this by locating your town on a map which features latitude and longitude.

2. Use the Sundial Hour Line Calculator to calculate the placement of hours for your latitude (see Resources below).

3. Draw the hour lines onto a rectangular piece of card stock for the angles determined by the calculator using a compass and straight edge. The hours of 6 a.m. and 6 p.m. act as your baseline, with each proceeding hour line draw along the correct angle.

4. Mark each hour line with the time it reflects. For example, for the line indicating 6 a.m., write "Six a.m." or "6:00 a.m."

5. Build a gnomon, the piece of the sundial which casts a shadow to indicate time, in the shape of an equilateral triangle out of balsa wood. You will need to use the same degree of latitude as your current location for the degree of the angles in the gnomon.

6. Attach the gnomon to the sundial along the line for 12:00 using tape or glue.

7. Take your sundial outside and place it on a flat surface in an open area, away from trees or other things that might interfere with the sun's rays. You may wish to use a level to ensure that the sundial is on a flat, level surface.

8. Use a magnetic compass to find the perfect placement for your new sundial. You will need to situate your sundial so that back side of the gnomon is facing due north.

Tell Time With a Sundial

1. Check the placement of your sundial by comparing the time shown with your watch. Sundials work best when they are set to standard time (not daylight savings time).

2. Look for the bottom edge of the shadow cast by the gnomon--it should align with the hour line closest to your local time.

Tips & Warnings

• The success of your sundial requires great attention to detail and precision. Use a compass and protractor to draw hour lines at the correct angle for your latitude.

Resources

• Sundial Hour Line Calculator