Su Song
There were many other important figures in the Song era besides Shen Kuo and Su Song, many of whom contributed greatly to the technological innovations of the time period. Although the mechanically driven mile-marking device of the carriage-drawn odometer had been known in China since the ancient Han dynasty, the "Song Shi" (compiled in 1345) provides a much greater description and more in-depth view of the device than earlier Chinese sources. The "Song Shi" states: