50 Things That Made The Modern Economy With Tim Harford

In 1845 a curious feature was added to the clock on St John's Church in Exeter, Western England.

Another minute hand running 14 minutes faster than the original.

This was, as Truman's Exeter flying post explained, a matter of great public convenience.

For it enabled the clock to exhibit, as well as the correct time at Exeter, the railway time.

The human sense of time has always been defined by planetary motion.

We talked of days and years, long before we knew that the Earth rotates on its axis and orbits the sun.

From the waxing and waning of the moon we got the idea of a month.

The sun's passage across the sky gives us phrases like midday or high noon.

Exactly when the sun reaches its highest point depends of course on where you're looking from.

If you happen to be an Exeter, you'll see it about 14 minutes after someone in London.

Naturally, as clocks became commonplace, people set them by their own celestial observations.

That was fine if you needed to coordinate only with other locals.

If we both live in Exeter and say we'll meet at 7 o'clock, it hardly matters that in London, 200 miles away, they think it's 7-14.

But as soon as a train connects Exeter and London, stopping at multiple other towns, all with their own idea of what the time is, we face a logistical nightmare.

Early British train timetables valiantly informed travellers that

London time is about 4 minutes earlier than Reading time, 7.5 minutes before Sirencester.

And so on, but many understandably got hopelessly confused.

More seriously, so did drivers and signalling staff which raised the risk of collisions.

So the railways adopted Railway time,

and they based it on Grennich meantime, set by the famous observatory in the London borough of Grennich.

Some municipal authorities quickly grasped the usefulness of standardising time across the country,

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