Zhu Yu (author)

Zhu Yu (Chinese: 朱彧; Wade–Giles: Chu Yü) was an author of the Chinese Song Dynasty (960–1279 AD). He retired in Huang Gang(黄岗) of the Hubei province, bought a country house and named it "Pingzhou". He called himself "Expert Vegetable Grower of Pingzhou (萍洲老圃)". Between 1111 and 1117 AD, Zhu Yu wrote the book Pingzhou Ketan (萍洲可談; Pingzhou Table Talks), published in 1119 AD. It covered a wide variety of maritime subjects and issues in China at the time. His extensive knowledge of maritime engagements, technologies, and practices were because his father, Zhu Fu, was the Port Superintendent of Merchant Shipping for Guangzhou from 1094 until 1099 AD, whereupon he was elevated to the status of governor there and served in that office until 1102 AD.

In terms of global significance, Zhu Yu's book was the first book in history to mention the use of the mariner's magnetic-needle compass for navigation at sea. Although the compass needle was first described in detail by the Chinese scientist Shen Kuo (1031–1095) in his Dream Pool Essays of 1088 AD, he did not specifically outline its use for navigation at sea. The passage from Zhu Yu's Pingzhou Ketan relating to the use of the compass states:

According to government regulations concerning seagoing ships, the larger ones can carry several hundred men, and the smaller ones may have more than a hundred men on board. One of the most important merchants is chosen to be Leader (Gang Shou), another is Deputy Leader (Fu Gang Shou), and a third is Business Manager (Za Shi). The Superintendent of Merchant Shipping gives them an unofficially sealed red certificate permitting them to use the light bamboo for punishing their company when necessary. Should anyone die at sea, his property becomes forfeit to the government...The ship's pilots are acquainted with the configuration of the coasts; at night they steer by the stars, and in the day-time by the sun. In dark weather they look at the south-pointing needle (i.e. the magnetic compass). They also use a line a hundred feet long with a hook at the end which they let down to take samples of mud from the sea-bottom; by its (appearance and) smell they can determine their whereabouts.

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