Circumference of the Earth

Try this

Use either equinox to your advantage to measure the circumference of the Earth using a method similar to that used by Eritosthenes! On the Equinox at astronomical noon, the sun is directly overhead at the equator (where the latitude is 0 degrees). At a point not on the equator, use the GPS to determine your latitude and the Inclinometer to determine the angle of the sun at astronomical noon at your location. Considering that the Earth makes up a full 360 degrees around, use the known difference in latitude from the equator, the known distance per latitude degree, and the difference in inclination of the Sun to determine the total distance around the Earth (approximated for the Earth as a perfect sphere).