Dividing the Day into One Hundred Ke: Classical Timekeeping in Totenroku 2.0
Totenroku 2.0 adopts the classical hundred-ke day. Starting from Gu Yanwu's textual study in the Rizhi Lu, this article explains how twelve double-hours and one hundred ke fit together—and why this older scale belongs in a modern journal of the sky.
We are used to dividing a day into twenty-four hours and every hour into sixty minutes. The system is precise and universal; it can feel almost indistinguishable from time itself.
Earlier Chinese timekeeping offered another way to see the day: one hundred ke per day.
Totenroku 2.0 adopts this classical system. A day in the app is no longer understood only through modern hours and minutes; it advances from zero to one hundred ke. This is more than giving the interface an archaic label. It lets the way we record time correspond to the stars, the sexagenary cycle, and the observational traditions already present in Totenroku.
How the Rizhi Lu explains one hundred ke
Gu Yanwu begins “One Hundred Ke” in the Rizhi Lu with a concise statement:
A day has twelve double-hours; counted in ke, a day has one hundred.
That immediately raises a problem. If each of the twelve double-hours were simply divided into ten ke, the total would be 120. Why, then, call it a hundred-ke day?
Gu explains that calendrical specialists distinguished between large and small ke. Each double-hour contained eight large marks—four for its first half and four for its second—giving ninety-six large ke across a day. Each double-hour also had two small marks, each worth one-sixth of a large one. The twenty-four small marks in a full day were therefore equivalent to four large ke. Added to ninety-six, they made exactly one hundred.
The twelve double-hours and the hundred-ke day were not contradictory. Different-sized marks gave the otherwise indivisible remainder a legible and usable place in the system.
The original passage and edition details are available through the Chinese Text Project.
How long is one ke?
If a modern twenty-four-hour day is divided evenly into one hundred ke:
24 hours ÷ 100 = 0.24 hours
1 ke = 14 minutes 24 secondsAt fifty ke, the day has reached modern noon. At one hundred, a new day begins.
This unit is finer than an hour without carrying the urgency of minutes and seconds. It is precise enough to place a moment of stargazing, a walk, or a journal entry, while retaining a little distance appropriate to the rhythms of the natural world.
Why change time in 2.0?
Totenroku has never been about placing old terms on a modern screen. The stars, the sexagenary cycle, calendars, and timekeeping once belonged to the same way of observing the world. If the foundation speaks only the language of a modern clock, a layer remains between them.
The hundred-ke day offers another entrance into the present. When an entry records “which ke of the day” it occurred in, it does more than replace the digits on a clock. It reminds us that a day can be divided in more than one way, and that time can have more than one texture.
Beginning with version 2.0, Totenroku will use one hundred ke as its classical scale of time. Modern time remains useful for orienting everyday life; the ke brings each record closer to what the app set out to preserve—the moment a person actually passed through within the movements of heaven and earth.