Compass and gun powder were invented before Qin Dynasty. In conquer war to unify separated China, Emperor Qin Shi Huang invented vehicle shaped compass and gun powder driven signal rocket to direct his armies in battle field.

An eunuch in Han Dynasty, named Cai Lun, found right process of papermaking. Paper was very expense record material at that time. As Cai Lun got assistance from his emperor for experiments, the art of papermaking was kept well by royal families only for long. Some smart merchants eventually spied the papermaking way and managed to produce paper too. But their process is not a perfect imitation of the royal one, paper made in the capital area, Luo Yang, was still better and more expensive. "Paper in Luo Yang is more expensive" became a Chinese idiom to explain a basic merchandise rule that price depends on demand.

Bi Sheng was a scholar. He felt very sorry for book copiers' pain when a finishing page was ruined due to a very small but fatal mistake. He invented types and typecase. As innovation to old printing, the invention released many book copiers from their pains and also made book making less expensive.

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