206 BCE


The book of science

Tom Sharp

Chinese, Han dynasty electromagnetism


  • Invented during the Han dynasty
  • to help feng shui practitioners
  • arrange people’s lives
  • to best align with qi,
  • the invisible forces
  • that bind everything together,
  • Chinese military and mariners
  • began to use compasses
  • during the Song dynasty
  • for navigating in bad weather.

Spoons, tadpoles

  • A lodestone suspended
  • from a silk string.
  • The south-pointing spoon
  • thrown onto the ground.
  • A south-pointing needle
  • shaped like a tadpole,
  • or a south-pointing fish,
  • floating in a bowl water.


  • To magnetize a needle
  • rub it with a loadstone
  • or heat it red hot
  • and douse it in water
  • while pointing it
  • toward the pole.


  • The earth around us has its yin,
  • exerting, and its yang, receiving,
  • even though elements interfere.
  • The compass swings from the south.
  • A massif, sometimes hidden underground,
  • water below a lake, shapes hidden forces.
  • It’s useless to oppose them
  • and it’s easy to make a mistake.
  • This is why you need our help.
  • Our aura of confidence helps.
  • We have a simple condition.
  • Don’t ask if you think you know better.

The compass extended the seasons when commerce and piracy could be conducted on the seas. In Europe, it helped create a source of wealth independent of royalty and the church.

See also in The book of science:

Readings on wikipedia: