Remember the drums
In ancient times used to record the vehicle from the distance of the carriage, the structure and the guide car is similar to the car up and down two layers, each layer of a wooden robot, hand Males, the lower wooden drums, the car every mile of the road, drumming about, the upper robot beat the bell, the car every ten miles, beat the bell once. Jin Huidi (259 years - 306 years) Taifu Cui leopard "ancient and modern note" records: "big chapter car, so the Road also, from the Xijing, also said in the car. People, line one, the lower drums; line ten miles, the upper bracelet. "Shangfang story" has a car law. " According to (Tang) Du You "Code" records, the Eastern Jin Dynasty Emperor Yi Hee thirteen years (417 years), Liu Yu off after Qin, was recorded in the drums. "Sun Zi calculated by" a division in the calculation of the problem, "there are Chang'an Luoyang nine hundred miles, the wheels of a round of ten feet, from Luoyang to Chang'an, asked round turn geometry?" Obviously and remember the drum car. ...