Double hour 1 of 12 · 時支
The Rat hour
子 Zi holds 23:00–00:59 on the modern civil clock. Tradition fitted the rat to it as the hour rats are boldest, when a still household is theirs.
One branch · four linked coordinates
What stays fixed in the Rat period
The clock selects one Earthly Branch. The same branch also carries a phase, compass direction and solar-term month; those links are structural coordinates, not extra personality labels.
五鼠遁 · day stem sets hour stem
Five complete Rat hour pillars are possible
The branch is fixed by the clock. The stem advances from the Day Master, so the ten day stems fall into five rule pairs and produce five possible hour pillars here.
- 01 · on 甲 Jia / 己 Ji days甲子Yang Wood Rat
- 02 · on 乙 Yi / 庚 Geng days丙子Yang Fire Rat
- 03 · on 丙 Bing / 辛 Xin days戊子Yang Earth Rat
- 04 · on 丁 Ding / 壬 Ren days庚子Yang Metal Rat
- 05 · on 戊 Wu / 癸 Gui days壬子Yang Water Rat
A period across two civil dates
Rat hour exposes the disputed day boundary
The period begins at 23:00 and ends at 00:59. A late-Rat-hour school starts the next sexagenary day at 23:00, while a civil-midnight school changes it at 00:00. The hour branch remains Rat; the day stem and therefore the hour stem can differ during 23:xx.
Known time
A recorded local time selects this branch and allows the hour stem to be derived from the day stem.
Unknown time
The hour pillar stays absent. Assuming noon or another default would invent two of the chart’s eight characters.
The same branch geometry at every scale
Its clash, harmony and trine do not change with the clock
The Rat branch clashes with Horse, forms Six Harmony with Ox, and belongs to the Water trine with Monkey and Rat and Dragon. These relationships come from fixed positions.