Sundials keep accurate time by casting a shadow relative to the angle of the sun in the sky. Sundials were first used by ancient civilizations. Some used a simple stick, called a gnomon, pushed into the ground, and others, such as the Egyptians, built large structures, called obelisks. Anyone could tell what time of day it was simply by looking at the shadow cast by the obelisk. However, because of the Earth's rotation, the shadow was not consistent day to day. People eventually discovered that aiming the piece of the sundial that casts the shadow to the north gave a more consistent reading.
Things You'll Need
- A place that is always in the sun
- Baking flour
- Magnetic compass
Video of the Day
Find a sunny spot to place the sundial. Set the sundial in the site and mark around its base with baking flour. (Flour will not harm the sundial's finish, and it washes away easily.)
Remove any grass or other plants at the site and level the ground. If the sundial is not level, its readings will be off.
Place the sundial back on the site. Check again to make sure it is level by placing the level on the top surface of the sundial. Check it twice; the second time, turn the level perpendicular to the direction you used for the first measurement. Modify the site as necessary until the sundial is level.
Use the compass to find due north. Rotate the sundial until the highest end of its style, the part that casts the shadow, is also pointing directly north.