Hexadecimal time
How to read it
Halve the day sixteen times and you get 65,536 equal parts, written as four hexadecimal digits from 0000 to FFFF. The first digit is the hex hour, the next two the hex minute, the last the hex second, separated by underscores: 8_00_0 is noon.
A hex hour is 1½ ordinary hours, a hex minute about 21.1 seconds, and a hex second about 1.318 seconds. Because every unit is a halving, the hour digit alone already tells you which sixteenth of the day you are in: anything starting with 8 to F is afternoon.
Where it came from
The Swedish-American engineer John W. Nystrom proposed dividing the day this way in 1863, as part of his “tonal system” of base-16 arithmetic.1 In 1997 Mark Vincent Rogers proposed a similar system and built it as a JavaScript clock.1 Neither caught on, but the notation is tidy, and this clock follows it.
Sources
- Hexadecimal time (Wikipedia, CC BY-SA 4.0)