Twenty-four mountains

Meaning

The twenty-four mountains, 二十四山 èrshísì shān, are the directions of the luopan, the Chinese compass: the circle cut into twenty-four sectors of 15°, three to each of the eight directions, each named after a Heavenly Stem, an Earthly Branch or a trigram. “Mountain” here means a direction. The classics say that a home sits in a mountain, the side it has its back to, and looks out to its facing, the mountain across the circle.

Twelve of the mountains are the Earthly Branches, all of them, the Rat’s Zi due north round to the Pig’s Hai. Eight are Heavenly Stems, all but Wu and Ji, the stems of Earth, which have no direction because Earth keeps the centre. Four are the corner trigrams, Gen, Xun, Kun and Qian, at the heart of the north-east, the south-east, the south-west and the north-west. In each cardinal direction a branch stands in the middle with the two stems of its phase on either side, Ren, Zi and Gui for the north’s Water; in each corner the trigram stands between two branches, an Earth branch before it and a branch that begins a season after it.

Ulune uses the mountains for the home. The facing a reader gives falls in one of them and the home sits in the one opposite; that pair, with the period of the building, sets the home’s Flying Star chart, and near a mountain’s edge the schools read a replacement chart or, on the line itself, a void line. The mountains also hold the year: the Grand Duke and the Year Breaker stand on branch mountains, and the Three Killings cover the three mountains of one cardinal direction.

In practice

• Finding the facing: the Home lens takes the facing as a compass reads it, typed or from the phone’s own compass, or from a map’s bearing turned into a magnetic one, and names its mountain with a short code: S2 is the south’s middle mountain, Wu.
• On the dial: the luopan the Home lens draws tints the facing mountain and dashes the one the home sits in; the nine palaces are then laid out from them.
• Near an edge: within 3° of a mountain’s edge Ulune shows the replacement chart that many schools read there beside the main one, and within 1.5° it says the facing is on a void line, which many schools read with care, and suggests taking the facing again, since a degree or two decides it.
• The year: the Cycles lens marks the year’s afflictions on the mountains. In 2026, a Horse year, the Grand Duke sits in Wu, the Year Breaker stands in Zi across from him, and the Three Killings cover the north’s three mountains, Ren, Zi and Gui.
• Two names: the corner mountains share their names with their trigrams, and a branch mountain with its branch: Ulune’s pages say “the Gen mountain” for the fifteen degrees, and “Gen” for the trigram that holds the whole corner.

Across traditions

• The ring of terms: many luopans carry the twenty-four solar terms beside the mountains, one to each. Each branch takes the middle term of its own month and the mountain before it the term that opens that month, so the solstices and equinoxes fall on Zi, Mao, Wu and You, and the four starts of the seasons on the four corner trigrams.
• The Western compass: the mariner’s rose of 32 points, 11.25° apart, meets the luopan only at the eight directions and on the eight lines between them, where its half-winds, north-north-east and the like, fall exactly on the luopan’s lines between directions.
• The Three Harmonies school, San He, reads the mountains in twelve pairs, each branch with the stem or trigram before it, Ren with Zi, Gui with Chou, Gen with Yin, round to Qian with Hai: the same pairs that share a month on the ring of terms.
• In India, Vastu Shastra divides the plan of a house among eight directions and their guardians, Indra in the east, Agni in the south-east, Kubera in the north; it has no ring of twenty-four, and reads every house by the same directions.

Origin and history

The twenty-four directions are older than the needle. The diviner’s boards of the Han dynasty found in tombs set the branches and the stems, all but Wu and Ji, round a square earth plate, and the Huainanzi (139 BC) follows the Dipper’s handle round twenty-four directions through the year, naming a solar term at each, Zi at the winter solstice, Gui at the Minor Cold, the corner of the north-east at the start of spring. When the magnetic needle came, the ring went with it: Shen Kuo described the needle and its slight turn to the east in 1088, and the luopan of the Song and later dynasties set the twenty-four mountains round its heaven pool, among rings for the stars, the years and the land. Ernest Eitel described its rings for Western readers in 1873, and Joseph Needham traced the boards and the needle in his history of Chinese science.

The mountains’ part in the Flying Stars comes from the Xuan Kong school: the three groups the classics call the Earth, Heaven and Man dragons, which give each mountain the polarity the stars fly by, and the verse that names each mountain’s replacement star. Shen Zhureng (1849–1906) set the method out in the form most schools use today.

How Ulune calculates it

Ulune counts 24 mountains of 15° clockwise from Ren, which begins at 337.5°: the facing a reader gives, magnetic as a luopan reads it, falls in one of them, a facing exactly on an edge belonging to the mountain after it, and the home sits in the mountain opposite. A bearing read on a map is turned magnetic first, with the declination of the World Magnetic Model 2025 at the chart’s place. It measures how far the facing lies from the nearest edge: within 3°, many schools read a replacement chart; within 1.5°, a void line, and it says whether that line runs between two of the eight directions or between two mountains of one.

For the Flying Stars each mountain has a polarity of its own, by its place: the first mountain of a direction is the Earth dragon, the middle one the Heaven dragon, the last the Man dragon. In the four cardinal directions the Earth dragon, a stem, counts as yang and the other two as yin; in the four corners the Earth dragon, an Earth branch, counts as yin and the other two as yang. When a number goes to the centre, the mountain that holds, in that number’s own palace, the place the home’s mountain holds in its own decides its flight: forward if it is yang, backward if it is yin; a 5, with no palace, flies by the home’s own mountain. Each mountain also has its replacement star from the classical verse, which Ulune’s tests check with the polarities against the published charts.

Correspondences