Guo Shoujing

1231-1316

Engineer and director of waterways

Sources

Early Life. Born in Hebei, Guo Shoujing was a precocious child. At the age of fifteen, coming across a diagram of the “Lotus Clepsydra,” he was able to understand at first sight the principle of this time-keeping device. In late 1251, when a bridge was washed away and no trace of its foundations could be identified, Guo Shoujing was put in charge of the restoration project. He first examined the area and located the site of the old bridge. He then cleared away the mud that covered its footings and had the structure rebuilt, thus guaranteeing pas-sage once again. Completed in only forty days, the project needed only four hundred laborers.

Water Clock. Sometime around 1260, Guo Shoujing cast a bronze water clock for a local observatory. Completed in 1262, it was subsequently moved to the capital, Beijing. He also built a tower for observing the twenty-eight lunar mansions as well as the larger stars and the constellations.

Irrigation. In 1260 Guo Shoujing had a chance to make a comprehensive survey of provincial irrigation systems. Praised for his expertise in waterworks and his unusual intelligence, Guo Shoujing was granted an audience with the emperor. On that occasion the scientist presented six different schemes for improving irrigation and waterways in the region north of the Yellow River. His knowledge greatly impressed the Mongol emperor Kublai Khan, who without delay appointed him superintendent of waterways for the various districts. In 1263 Guo Shoujing received the rank of vice commissioner of waterways, and he was given a silver table.

Recommendations. Guo Shoujing became vice director of waterways two years later. On his way to the capital he sailed four days and nights on the Yellow River and conducted the first survey of the upper reaches of the river. He discovered that this particular section was navigable for large cargo boats. After observing many derelict canals, he recommended the old canal be widened and deepened so that it could be used for both navigation and irrigation while safely draining away any excess water. His recommendations were adopted.

Canals. In 1272 Guo Shoujing received an appointment as director of waterways. Another large canal was built joining the nearby rivers for irrigation. Kublai Khan ordered all the people from chancellors down to civil servants to form a work-force under Guo Shoujing’s supervision. Completed by 1293, the canal greatly improved communications in the area and made it easier to transport foodstuffs into Beijing. For his achievement Guo Shoujing received a cash reward and was assigned to administer the building of another new canal.

Calendar. In 1276 Kublai Khan decreed that a new calendar be devised. According to Guo Shoujing, the accuracy of any calendar depended on the accuracy of the observations made by astronomical instruments. He set about to construct seventeen different astronomical instruments. In 1280 the Calendar for Fixing the Seasons was finally completed and formally presented to the court. The khan ordered its formal adoption in the first month in 1281.

Importance. Guo Shoujing died in 1316 at the age of eighty-three. In light of his many creative and original contributions, this scholar was regarded as the most outstanding hydrologist and astronomer of the Yuan dynasty (1279-1368) and the last of the great traditional mathematicians in Chinese history.

Sources

Robert Payne, The Canal Builders: The Story of Canal Engineers through the Ages (New York: Macmillan, 1959).

Igor de Rachewiltz, ed., In the Service of the Khan: Eminent Personalities of the early Mongol-Yuan Period, 1200-1300 (Wiesbaden: Franz Steiner, 1976).