1. Measure the distance between the two feet of the compass with a ruler as the radius.
2. Fix the end in one place with a needle as the center of the circle.
3. Turn one end once with a pencil.
Compass is a tool for drawing circles or strings in mathematics and drawing, and is often used for drawing with a ruler.
The invention of the compass can be traced back to the Xia Dynasty in China. Historical Records Xia Benji recorded Dayu's "left rope and right gauge" for water control. In Oracle Bone Inscriptions in the 5th century BC/KLOC-there were already rules and moments, which were called "rules" at that time, that is, compasses.
"Zhou Li Kao Gong Ji Craftsman" records: "The craftsman founded the country, the ground hangs, and the raft hangs, depending on the scene. For the rules, know the sunrise scene and the sunrise scene. Participate in the Japanese-Chinese scenery during the day, and the star of the night test is to grab the sky. "
Shandong Jiaxiang Wuliang Temple has a brick statue of Fuxi Nuwa in the Eastern Han Dynasty. Nuwa abides by the rules and Fuxi abides by the rules. The custom here is Guliang custom, and its shape is similar to Oracle Bone Inscriptions's "Gui". A drawing tool for drawing circles.
There are two feet, the upper end is hinged, and the lower end can be separated or closed at will to adjust the radius of the drawn arc. The end of one foot is a needle tip, and the end of the other foot can be fitted with a foot for drawing pencil lines or ink lines.
Some compasses are equipped with telescopic rods to draw larger circles. There are beam compasses, spring compasses and movable core compasses.