Original Post from Ilya Grigorik: "Hours of fixed length became commonplace only after mechanical clocks first appeared in Europe during the 14th century... It was not practical for the general public to consider minutes until the first mechanical clocks that displayed minutes appeared near the end of the 16th century." ... fascinating read. Why is a minute divided into 60 seconds, an hour into 60 minutes, yet there are only 24 hours in a day? - mjc