指南针思维导图

这是一个关于古代四大发明指南针的思维导图。指南针，古代叫司南，主要组成部分是一根装在轴上的磁针，磁针在天然地磁场的作用下可以自由转动并保持在磁子午线的切线方向上，磁针的南极指向地理南极(磁场北极)，利用这一性能可以辨别方向。

compass

• notion
  • A device showing geograhic directions
    • by using the earth's magnetic field
    • enable trade and exporation to develop on a worldwide scale
• materials
  • the spoon-orladle-shaped compass
    • magnetic lodestone（天然矿石）
  • the plate
    • bronze
      • 捡灯
      • 打灯
      • 观灯
  • symbolization
    • circular centre
      • Heaven
    • square plate
      • Earth
• influence
  • historic ocean voyages
    • Zheng He's seven voyages
      • Western Seas
    • Christopher Columbus
      • America
    • Vasco da Gama
      • India
    • Ferdinand Magellan
      • round-the world voyage
  • globalization
    • economic development
    • Promote cultural communication
• origin
  • Early in the Warring States period
  • • the earliest record
      • Song dynasty
  • China characters on the plate denote the eight main directions
• compass vehicle
  • an earlier and more primitive form
  • an ancient Chinese vehicle
    • gear wheels and wooden figure
  • always opiont out south