The Ninja Compass

What! Did the ninja also make compasses?

Although this was not directly related to their knowledge of herbs and medicine, the ninja also handmade their own compasses which always pointed north. These compasses were called “kishuku”. Iron would be magnetized by heating it until it was red hot, and then plunging it into cold water to cool. The magnetic piece of iron was then flattened and made into the shape of a boat. This could then be floated in water, and the direction in which the boat pointed was north.