Jing Fang

Jing Fang (Chinese: 京房; pinyin: Jīng Fáng; Wade–Giles: Ching Fang, 78–37 BC), born Li Fang (李房), courtesy name Junming (君明), was born in present-day 東郡頓丘 (Puyang, Henan) during the Han Dynasty (202 BC – 220 AD). He was a Chinese music theorist, mathematician and astrologer. Although better known for his work in musical measurements, he also accurately described the basic mechanics of lunar and solar eclipses.

The historian Ban Gu (32–92 AD) wrote that Jing Fang was an expert at making predictions from the hexagrams of the ancient Yijing. A book on Yijing divination attributed to him describes the najia method of hexagram interpretation, which correlates their separate lines with elements of the Chinese calendar.

According to the 3rd century historian Sima Biao, Jing Fang received an appointment as an official in the Music Bureau under Emperor Yuan of Han (r. 48–33 BC).

Jing Fang was the first to notice how closely a succession of 53 just fifths approximates 31 octaves. He came upon this observation after learning to calculate the pythagorean comma between 12 fifths and 7 octaves (this had been published ca. 122 BC in the Huainanzi, a book written for the prince of Huainan), and extended this method fivefold to a scale composed of 60 fifths, finding that after 53 new values became incredibly close to tones already calculated.

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