I pride myself on doing my research thoroughly and efficiently—as my course, Rein in Your Research attests. Yet the one topic I always have to investigate again and again when I write novels set before the 17th century concerns measurement. Many of the units and types of measurement we take for granted weren’t in common use before then, if they existed at all. Which makes describing how far, how long, how much time etc. a bit trickier than it might seem.

Our everyday obsession with measurement is only a few centuries old.

Face it: The concept of measurement saturates everything we do—at least in the West. I have an Apple Watch that measures the time, the temperature outside, my activity level, and my pulse rate. It also times my hand-washing to 20 seconds and rewards me with digital confetti.

Everywhere I look when I’m working, something is there to monitor the day slipping away, minute by minute. It wasn’t always like that, which is important to realize when you’re writing medieval historical fiction.

Talking about minutes is a hard habit to break.

It’s so easy to slip into using modern units of measurement when trying to indicate time, distance, seasons, and money. But back in the thirteenth century, people experienced all of those aspects of life differently from the way we do today. Units of time are especially slippery, in that they creep in so surreptitiously that it’s easy to make mistakes.

Egyptian Clock

Oldest existing sundial

But let’s back up a second. We actually owe the concept of dividing a day into 12 parts to the Egyptians. The reason for 12, apparently, is that it’s a number that can be counted on the finger joints of one hand (minus the thumb). Who knew?

That’s all well and good, but how long was each of those divisions, or hours? Fixed-length hours didn’t come into being until much later, with Hipparchus (active 147–127 BCE). He based the divisions of periods of light and dark on their lengths on the day of the equinox. Nonetheless, most people still used the unequal hours for centuries after that, until mechanical clocks came to Europe in the 14th century.

Minutes are an old concept too, but not in Europe.

As to why sixty minutes in an hour? That started with the Babylonians, who made astronomical calculations in base 60. These calculations translated to latitude and longitude (don’t ask me exactly how). From there, we creep closer to hours, minutes, and seconds. I’m going to let Michael A. Lombardi, a metrologist in the Time and Frequency Division at the National Institute of Standards and Technology in Boulder, Colo., explain:

In his treatise Almagest (circa A.D. 150), Claudius Ptolemy explained and expanded

Elephant clock

on Hipparchus’ work by subdividing each of the 360 degrees of latitude and longitude into smaller segments. Each degree was divided into 60 parts, each of which was again subdivided into 60 smaller parts. The first division, partes minutae primae, or first minute, became known simply as the “minute.” The second segmentation, partes minutae secundae, or “second minute,” became known as the second.

It’s actually all pretty complicated. And although the calculations and the technology was there, clocks that actually indicated minutes didn’t appear until the 16th century. If you want to know more, read this article in Scientific American.

Just to confuse things, the Catholic Church had its own hours.

The nine canonical hours in the medieval church were not hours as defined by the Egyptians. They divided the day (and night) into fixed times of prayer, most of which were three hours apart. Why were there nine? I’m tempted to believe the hours of prayer were created to make it impossible for monks and nuns to either work or sleep uninterrupted. You judge, from the Wikipedia entry on canonical hours:

  • Vigil (eighth hour of night: 2 a.m.)
  • Matins (a later portion of Vigil, from 3 a.m. to dawn)
  • Lauds (dawn; approximately 5 a.m., but varies seasonally)
  • Prime (early morning, the first hour of daylight, approximately 6 a.m.)
  • Terce (third hour, 9 a.m.)
  • Sext (sixth hour, noon)
  • Nones (ninth hour, 3 p.m.)
  • Vespers (sunset, approximately 6 p.m.)
  • Compline (end of the day before retiring, approximately 7 p.m.)

Of course, if Compline prayers took place as early as 7 p.m. instead of 9 p.m. and the monks or nuns didn’t attend Vigil (which was one of the minor hours), they would have an 8-hour sleep.

In any case, that doesn’t answer the question of why. Apparently it’s in the Bible somewhere.

The fact is, in communities close to an abbey or monastery, the bells calling the brethren to prayer would have served to mark the time of day. That and, of course, the sun.

Why all this matters when writing medieval historical fiction is that there was no such thing as, say, ten o’clock. Or “I’ll be there in a minute.” Or “Just a second.” That’s actually a good thing, because it forces a writer back in time to inhabit the character and really embody how that character would have experienced or been aware of the time.

All this reminds me of my years in London, when a clever way to say “I’ll be right there” was, “I’ll be there in two shakes of a lamb’s tail.” That definitely would have worked in the Middle Ages!