Inventing Noon

For nearly all of human history, the question what time is it? had an unambiguous local answer and no general one.

Noon was the moment the sun stood highest. That moment is genuinely different in different places: the earth turns fifteen degrees of longitude in an hour, so two towns sixty miles apart on an east–west line experience noon about four minutes apart. A church clock or a market clock was set against the sun, adjusted when it drifted, and this was not an approximation of the correct time. It was the correct time, and there was no other kind. Every town of any size kept its own, and the differences between them were real, measurable and completely irrelevant.

They were irrelevant because nothing moved fast enough for anyone to notice. A traveller on horseback covering forty miles in a long day arrived to find the local clocks three minutes out and did not care, because the discrepancy accumulated at roughly the speed of travel itself. Time, like weather, was a local condition.

Two inventions destroyed this arrangement within about forty years, and it is worth being precise about their different roles. The railway made the differences matter. The telegraph made them visible.

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Consider the practical problem a railway company faces.

A train leaves a terminus and arrives at a station ninety miles west, where the clock reads six minutes earlier. The timetable must be printed in some time, and passengers must consult it against some clock, and the stationmasters along the route must agree about when the train is due. Worse, on single-track lines — which most early lines were — the entire safety system rested on trains occupying agreed sections at agreed moments. A misunderstanding about which town's noon was intended was not an inconvenience. It was a collision.

British railway companies resolved this with characteristic directness: they simply ignored local time. From 1840 onwards, one company after another ran its operations on the time kept at the observatory at Greenwich, distributed initially by carrying accurate chronometers on the trains themselves and, before long, by telegraph. The practice acquired a name — railway time — and it was for some years genuinely parallel to the older system rather than replacing it. Certain stations installed clocks with two minute hands, one showing the local time and one showing the railway's, a solution that is either elegantly pragmatic or quietly absurd depending on your temperament.

For a while the country operated on two times at once, and the boundary between them ran through daily life in peculiar ways. There is a well-documented case from 1858 in which a court sat in a town keeping local time, a defendant arrived at the hour shown on the railway clock, and, having by the court's reckoning failed to appear, lost the case by default. The appeal turned on which clock the law recognised. The answer, at that date, was local time — because nobody had ever legislated on the question, there being nothing to legislate about.

Britain settled the matter by statute in 1880, defining the legal time throughout Great Britain as that kept at Greenwich. The remarkable thing is not that this happened but that it took forty years, and that the country ran a national railway network for four decades in a state of formal legal ambiguity about what time it was.

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The American case was larger and consequently more vivid.

A continent spanning more than fifty degrees of longitude, with railway companies operating over enormous distances, produced a situation of genuine confusion. Contemporary accounts describe hundreds of local times in commercial use and something over fifty distinct company standards, with major junction stations displaying a row of clocks, one for each line, and travellers expected to work out the arithmetic themselves.

The resolution came not from any government but from the railway companies acting jointly. Meeting in 1883, they agreed to divide the continent into four bands, each keeping a time one hour apart from its neighbours, and to implement the change simultaneously on the eighteenth of November.

That Sunday was known afterwards as the Day of Two Noons. In each zone, clocks reached noon by local reckoning, were stopped, and were restarted at noon by the new standard — so that in most places the same minute was lived through twice, and in others a few minutes of the afternoon simply never occurred. Telegraph signals from observatories coordinated the moment. Newspapers reported crowds gathering to watch public clocks being adjusted, an occasion whose strangeness is easy to underrate: an entire society, by agreement, stepping sideways in time.

It should be recorded that the change was not universally welcomed. Objections were raised in the press and from municipal authorities, and they were of two kinds. The first was practical and turned on local autonomy: a town's clock was the town's business, and it was not evident why a private railway corporation should determine when its inhabitants ate lunch. The second was, in a loose sense, philosophical. Time as shown by the sun was a fact about the world; time as agreed by companies was a convention. To adopt the second was to accept that the hour had become an administrative artefact rather than an observation — which is precisely what happened, and which remains true every time you set an alarm.

The American federal government did not legislate on the matter until 1918, thirty-five years after the railways had made the decision and the public had, grumbling, complied.

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The final piece fell into place in 1884, when an international conference met to select a common prime meridian, so that the zones could be numbered from a single agreed origin rather than each nation counting from its own capital.

Greenwich was chosen, by a substantial majority with a small number of abstentions, largely on the unromantic ground that a large share of the world's shipping already used charts based on it, and the cost of changing would have fallen on the people least able to bear it. Practical arguments generally win these contests, which is why the world's time is reckoned from a suburb of London rather than from anywhere with a better claim to centrality.

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What was lost in all of this is worth naming, because it is subtle and it was not obvious to anyone at the time.

Before standardisation, the time was something you could check by looking upward. It was derived from a visible fact, available to anyone, requiring no authority to confirm it. After standardisation, the time became something you are told — by a signal, a network, a server — and there is no longer any way for an individual to verify it independently, because the thing being reported is not an astronomical event but an agreement.

We gained a world in which a meeting can be scheduled between three continents without anyone having to think about it. We gave up, permanently and without discussion, the idea that noon is when the sun is overhead.