People say it every day without thinking ― “two o’clock,” “six o’clock,” “eight o’clock sharp.” But what is the purpose of that little “o” and apostrophe? Is it short for something? Why do we only use ...

From the sundials and water clocks of the ancient Egyptians, through the first marine chronometers, to modern day atomic clocks, humans have embarked on a quest to measure time with ever increasing ...