China: The face or 'heavenly dial' of a 'luopan' Chinese magnetic compass, also...

Like a conventional compass, a luopan is a direction finder. However, a luopan differs from a compass in several important ways. The most obvious difference is the Feng Shui formulas embedded in up to 40 concentric rings on the surface. This is a metal or wooden plate known as the heaven dial. The circular metal or wooden plate typically sits on a wooden base known as the earth plate. The heaven dial rotates freely on the earth plate. A red wire or thread that crosses the earth plate and heaven dial at 90-degree angles is the Heaven Center Cross Line, or Red Cross Grid Line. This line is used to find the direction and note position on the rings. A conventional compass has markings for four or eight directions, while a luopan typically contains markings for 24 directions. This translates to 15 degrees per direction. The Sun takes approximately 15.2 days to traverse a solar term, a series of 24 points on the ecliptic. Since there are 360 degrees on the luopan and approximately 365.25 days in a mean solar year, each degree on a luopan approximates a terrestrial day. Unlike a typical compass, a luopan does not point to the north magnetic pole of Earth. The needle of a luopan points to the south magnetic pole.