This is 99% invisible. I'm Roman Mars.

For the most part, we take time for granted. Maybe we don't have enough of it, but at least we know how it works.

At least, you know, most of the time. A lot of what we think about time and how we keep track of it is relatively recent.

And some aspects that we take for granted aren't actually all that universal.

And today, we're going to be talking to a few of my 99 PI colleagues for a set of many stories about our evolving relationship with time.

And to get us started, it's Kurt Colstead, the co-author of the 99% invisible city. And in our book, we wrote about the standardization of time that came with the rise of railroads.

Right. And before standard times, rail companies had to juggle all of these city-specific time zones.

But there's one really neat artifact in particular from that period, which really brings the point home.

So here's this old or eight clock that hangs on the facade of the Bristol Corn Exchange Building in England.

So this is a lovely clock with red letters and red hands, except for there seems to be kind of what looks like a long black, you know, almost like a second hand potentially, but you know, I can't quite make sense of what it's for.

Yeah, yeah, one could definitely think that's the second hand, but it's actually a second minute hand. So there are two different minute hands and they're set about 10 minutes apart from each other.

And they're painted those different colors so that, you know, people on the streets below can tell them apart.

So does this second minute hand also have to do with trains?

Absolutely. So they have this one hand that's for Bristol.

And then when train travels started becoming more commonplace, they added a second minute hand to show London time. And that's the one that's colored black.

Got it. So one hand is for locals that they're still on the local time. The other is for people traveling in and out of the city.

And presumably that the local time is based on high noon when they sonnest highest in the sky. That's what we talk about in the book.

How did they get this London time that that's showed here in this picture about 10 minutes off? Right. So that's the crazy part.

Apparently they actually sent people out from London on trains with these precisely tuned watches. And so that way they could keep clocks like this one up to date on London time.

So the railroad used the train network to keep track of time.

Yeah, it's sort of this weird meta phenomenon. And so you have these dedicated time keepers who would arrive in a given town.

And then they'd hop off the train and they'd go show their watch to the station master because the local railroad operators needed to know the precise time in London.

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