Using nothing but a compass as a navigational tool, ancient mariners from China to Sumer navigated the world’s oceans. Even in the modern age of GPS, the magnetic compass is anunfaltering navigational tool for seagoing vessels, airplanes and hikers on the ground.
When a tree falls and there is no one there to hear it, does it make a sound? It depends on what you mean by sound. We think we know what it means because our perception of sound is second in importance only to sight.
By Richard Brill email@example.com Posted on December 4, 2015 • Updated on December 4, 2015 at 2:37 am
The earliest clocks relied on the movements of the sun and stars. A sundial consists of a stick or gnomon that casts a shadow on a flat surface with numbers to represent hours or other measures of time.