For 'Customary' in Linacre's subtitle, read 'Imperial': his guide is a compelling argument for the natural supremacy of the duodecimal system and also covers topics such as the megalithic yard, cosmic numerology and the number 42.

In the seventh century a yard was as much a reckoning of the worth of some land as a set measure of its dimensions and, although the term came to mean a unit of distance, the 36-inch standard was not settled until 1855. This light-hearted compendium explores the origins of our weighing, measuring and timing systems from the Babylonian calendar to the metric system.