Time and directions

In addition to their role as signs of the zodiac, the Twelve Branches were also used to refer to times of the day and geographical directions. The diagrams below illustrate the relationships.

Time

The day was divided into halves, with the two-hour period centered on midnight designated as the Hour of the Rat. When finer distinctions were necessary, the two-hour periods were divided into numbered quarters of 30 minutes each; the designation ushi-mitsu, or “ox-three,”for example, would refer to the 30-minute period between 2:00 am and 2:30 am, the third quarter of the Hour of the Ox.

Another way of calculating time seems to have been based on the importance to divination of multiples of nine, so that the first instance (corresponding to midnight) is kokonotsudoki (“nine of the clock”) and a countdown of sorts begins from that point, with two times nine equal to 18, which — ignoring the leading digit — yields yatsudoki (“eight of the clock”), three times nine equals 27, and hence 27 –> 7 –> nanatsudoki (“seven of the clock”), and so on, down to yotsudoki (“four of the clock”). The points midway to the next “hour” were designated “halfway” points (-han; ~半).

There were variations on this system in different historical periods, other terms exist for different ranges of time within the 24-hour day, and in addition there is a theory that holds that the Hour of the Rat actually began at midnight, so that the method indicated by the diagram cannot be considered perfectly reliable in all cases.

Directions

Each of 12 directions took the name of one of the Branches, beginning with “Rat” in the north, and special designations were added for the northeast, southeast, southwest, and northeast based on the names of the two adjoining Branches. The northeast and southwest were considered unlucky directions (kimon and ura-kimon, respectively), forming the basis for the practice of avoiding travel in those directions (katatagae).