Over on the new HH Instagram feed last week was the fact that a moment was once precisely defined as 1/40th of an hour—or exactly 90 seconds. This is a subject that’s popped up on HH before (and if you have The Accidental Dictionary—now available in the States!—then you’ll already know this story). But for the uninitiated, here’s the tale.
Moment comes to us from the Latin word for “movement”—a word we also use in English to mean the inherent impetus or quantity of motion held by a moving body: momentum.
With that definition in mind, the word moment originally referred to a tiny amount of either time or weight that corresponded to only the slightest movement of, say, the needle of a balance or the hand of a clock. It’s from here that the move familiar use of moment to mean “an unspecified and brief amount of time” derived. So who set the clock to precisely 90 seconds?
Well, when timekeeping and our knowledge of the solar and lunar cycles became ever-more accurate in the fourteenth century, scholars began using a host of words to divide up the day into sections of varying length.
So by mediaeval reckoning, each of the day’s hours were divided into four points, each 15 minutes long. Each point was in turn divided into 10 moments, each equal to 1/40th of an hour, or a minute-and-a-half. Each moment was then split into 12 ounces, each one equivalent to 7½ seconds. And, smallest of all, each ounce was ultimately divided into 47 atoms—of which there were 22,560 in an hour. (The word atom, incidentally, literally means “undividable” or “uncuttable”, as it was too small to be divided into any smaller elements.)
Not all of these lengths of time were used concurrently, and not all of them would have been used by all mediaeval timekeepers. But nevertheless, use of the word moment to mean 1/40th of an hour was widespread enough to earn itself a place in the language, and this somewhat precise definition of a moment remained in use until the mid 1600s.