Update from early review which had been lost The 5,000 year struggle to align the clock with reality - and what happened to the missing ten days. Struggle is the word. It wasn't until 1949 that China joined the rest of the world on the Gregorian calendar - and the rest of us still suffered many hundreds of years on calendars that were hopelessly adrift with respect reality. There is a good opportunity for a mix of exploring historical characters and the very arbitrary formation of the 'human' side of the calendar - why is February the short month? Why is the tenth month called the eighth? - alongside the gradual astronomical developments that would pin the calendar the motion of the earth. Like many of the very tightly focused popular science books, this can be a little samey in places, but it is a fascinating story and rewards the reader throughout with delightful insights. What it lacks in narrative flow, it makes up with information that is well worth the effort.