> Before the 1800s the day began when the sun came up, this varied every day. See (variable-length/unequal) temporal hours: > Adapting the European clock desi

> Before the 1800s the day began when the sun came up, this varied every day. See (variable-length/unequal) temporal hours: > Adapting the European clock designs to the needs of Japanese traditional timekeeping presented a challenge to Japanese clockmakers. Japanese traditional timekeeping practices required the use of unequal time units: six daytime units from local sunrise to local sunset, and six night-time units from sunset to sunrise. > As such, Japanese timekeepers varied with the seasons; the daylight hours were longer in summer and shorter in winter, with the opposite at night. European mechanical clocks were, by contrast, set up to tell equal hours that did not vary with the seasons. * https://en.wikipedia.org/wiki/Japanese_clock#Temporal_hours https://en.wikipedia.org/wiki/Japanese_clock#Temporal_hours * https://en.wikipedia.org/wiki/Hour#Unequal_hours https://en.wikipedia.org/wiki/Hour#Unequal_hours * https://en.wikipedia.org/wiki/Unequal_hours https://en.wikipedia.org/wiki/Unequal_hours