has words for the four cardinal directions, Chinese mariners and astronomers/astrologers preferred using the 12 directions of the Earthly Branches, which is somewhat similar to the modern-day practice of English-speaking pilots using o'clock for directions. Since 12 points were not enough for sailing, 12 midpoints were added. Instead of combining two adjacent direction names, they assigned new names: For the four diagonal directions, appropriate trigram names of I Ching were used. For the rest, the Heavenly Stems (1–4, 7–10) were used. According to the Five Elements theory, east is assigned to wood, and the Stems of wood are (jiǎ) and (yǐ). Thus, they were assigned clockwise to the two adjacent points of the east. The 24 directions are: Advanced mariners such as Zheng He used 48-point compasses. An additional midpoint was called by a combination of its two closest basic directions, such as (bǐngwǔ) for the direction of 172.5°, the midpoint between (bǐng), 165°, and (wǔ), 180°. Current usage The terrestrial branches are still commonly used nowadays in Chinese counting systems similar to the way the alphabet is used in English. For example, names in legal documents and contracts where English speakers would use K, L, M, etc. Korea and Japan also use terrestrial branches on legal documents in this way. Since the celestial stems and terrestrial branches combined only consist of 22 characters, the four final letters – W, X, Y, and Z – cannot be represented by any of the celestial stems and terrestrial branches, and those four letters are represented by ‘物’, ‘天’, ‘地’, and ‘人’, respectively, instead. In case of upper-case letters, the radical of ‘口’ (the ‘mouth’ radical) may be added to the corresponding terrestrial branch or any of ‘物’, ‘天’, ‘地’, and ‘人’ to denote an upper-case letter. See also Heavenly Stems (天干) Sexagesimal cycle (干支) Sheng Xiao Chinese calendar References External links Technical factors of Chinese astrology Jupiter (mythology) Eastern esotericism