Archive: The Measurement of Time

Misha Glenny (0:00)

Hello, Misha Glenny here. Welcome to the first of my Archive Picks. Every Monday, I'll be exploring the riches from the In Our Time Archive and bringing back an episode hosted by Melvyn Bragg that I think deserves another listen. And you'll still find brand new episodes of In Our Time every Thursday. For the first in this series of Archive Editions, we're starting with an episode on the measurement of time.

Measuring time starts with the sun, the moon and the stars, in that order, unless you're indigenous to the Arctic, in which case the last two often muscle out the first. But did you know why we then started measuring hours in multiples of 60? Or that water dripping into a bowl determined how long you were allowed to speak in court? We've only been measuring time with any accuracy for about 500 years, but as Melvyn and his guests in this week's Archive episode of In Our Time observe, we've been obsessed by the need to calibrate and catch this intangible concept for much, much longer.

I hope you enjoy listening.

Melvyn Bragg (1:10)

Hello, we'll be talking about time. You can't stop it, you can't touch it, but it threatens to take over our lives. It's hard to imagine a time when the days and nights weren't divided up into the hours and minutes that we know today.

It was only in the late 19th century that time was standardised globally and that Glenwich was chosen as the location of the Prime Meridian. The history of the measurement of time is a long one, from earlier man tracing his days from sunrise to sunset, to the advent of atomic clocks in the 1950s. We've constantly striven to calculate and control the time. But how did mechanisms for measuring time develop into such precise machines? And how did the changes in society drive the need for such precise timekeeping?

With me to discuss the history of the measurement of time are Kristen Lippincott, former Director of the Royal Observatory, Greenwich, Jim Bennett, Director of the Museum of the History of Science at the University of Oxford, and Jonathan Betts, Senior Curator of Horology at the Royal Observatory, Greenwich. Kristen Lippincott, how did early, earliest civilizations measure using the natural phenomenon, measure time?

Kristen Lippincott (2:17)

Well, I think the thing one has to do, because it's so hard to think about time without thinking about watches. But imagine that you're primitive man and what you're noticing going around you. Essentially, the first thing you're going to notice is the sun, because that separates the light into the dark. Then you start to notice the phases of the moon, and then finally you start to notice the regular cycle of the stars. So you can see in all of these ancient people's minds, they had three different components that were naturally dividing up their day.

Melvyn Bragg (2:51)

And how did they set about calculating? Do we have a record of the earliest calculations?

Kristen Lippincott (2:56)

We don't have any calculations, well, until quite late, which is say 2500 BC.

But we know that people were watching things like the phases of the moon, because we have ancient bones like shoulder bones or narwhal bones, where they actually carved the different phases of the moon in a regular way. So, it's something that they were tracking, but measuring comes quite late.

Melvyn Bragg (3:21)

Were they tracking the stars as well, earlier than 2500 BC, which is long enough ago?

Kristen Lippincott (3:25)

Very, very early. They were primarily interested in what we'd call horizon phenomenon, i.e. what's rising on the horizon or setting on the horizon with the sun, because the sun was always the primary deity in all of the religions that basically were below the Arctic Circle. Of course, above the Arctic Circle, like with the Inuit, you get a moon goddess instead, because they didn't see the sun for half the year.

Melvyn Bragg (3:51)

Did they have any technology to help them to look, or were they just using what we call the naked eye?

Kristen Lippincott (3:57)

Very early on, they were probably using, well, first of all, they were using land masses. So they would have, and this is why you'd have a sacred mountain or a sacred stream that would be maybe pointing to the west or maybe pointing to the east, and they would use the land masses to define how they would measure the passage of the sun or the passage of the stars.

Melvyn Bragg (4:18)

So when the sun is above that mountain there?

Kristen Lippincott (4:20)

We know that it's the spring equinox or something like that, or the winter solstice, and then, of course, much later you get them setting up big stones. They make their own artificial mountains.