(My copy is not OUP, but Folio Society, and is called 'A short history of time'.)
Fascinating, though sometimes mind-numbing in detail.
Different ways people have measured years, months, seasons. Different ways to count what they measure. Or to correct what they measure. When was Easter? Can you have a new year on a Sabbath? Which languages preserved names of gods in their days of the week? All these things and more included in this work.