How the train timetable gave the world a shared clock
Today it seems obvious that everyone in a country should share the same time. For most of history, however, time was a local matter, decided by the sun. In any town, noon was the moment when the sun stood highest in the sky, and public clocks were set accordingly, usually by checking them against a sundial. Because the Earth turns from west to east, the sun reaches its highest point later the further west one travels – about four minutes later for every degree of longitude. As a result, in the early nineteenth century, clocks in Bristol ran roughly ten minutes behind those in London, and in Penzance, near the western tip of England, the difference was more than twenty minutes.
For centuries, these differences caused few difficulties. With journeys so slow, a gap of a few minutes between one town and the next simply went unnoticed. Travelling from London to Bristol by stagecoach took the best part of a day, and those travellers who carried pocket watches could adjust them on arrival, much as a modern traveller changes the time on a phone after a long flight. For most people, the only time that mattered was the one shown by the church clock in their own town, and because that clock followed the sun, it also matched the hours of daylight by which most of them worked.
The railways changed this almost overnight. A train could cover the same distance in a few hours, and timetables had to show departure and arrival times for every station along the line. If each station kept its own local time, a timetable became a puzzle, and passengers could easily miss their trains. More seriously, on many lines trains were kept apart largely by the timetable, so confusion over time could lead to collisions. In November 1840, the Great Western Railway became the first company to run all its services on London time, and others soon followed. In 1847, the organisation that coordinated Britain's railway companies recommended that all of them adopt Greenwich time, and within a year most had done so. The arrangement became known as 'railway time'.
Keeping every station clock accurate was a further challenge. At first, guards on trains often carried watches set to London time, which station staff used to correct their clocks. From 1852, however, the Royal Observatory at Greenwich began sending time signals along the telegraph wires that ran beside many railway lines, so that clocks hundreds of kilometres away could be checked almost instantly. By the mid-1850s, the great majority of public clocks in Britain showed Greenwich time.
Not everyone welcomed the change. Some people saw railway time as London forcing its habits on the rest of the country, and a number of towns went on keeping their own time for years. Bristol was among those that resisted, and a clock on the front of its Corn Exchange still has two minute hands, one showing London time and the other local time. In such places, people effectively lived with two times: railway time for catching trains and local time for everything else. The confusion ended only in 1880, when an Act of Parliament made Greenwich Mean Time the legal time throughout Great Britain.
In the United States, the problem was far larger. Each railway company set its own time, usually that of its headquarters or of a major city on its route, and by the early 1880s dozens of different railway times were in use. Some large stations, served by several companies, displayed a row of clocks, each showing a different time. On 18 November 1883, the railway companies of the United States replaced this confusion with four standard time zones, each one hour apart. In cities where the clocks had to be put back, noon arrived twice that day, and the date became known as 'the day of two noons'. Remarkably, the whole scheme was organised by the railways themselves; it did not become federal law until 1918.
The idea soon spread beyond the railways. A Canadian railway engineer, Sandford Fleming, had already proposed a worldwide system of twenty-four time zones; according to a popular story, his interest began when a misprinted timetable made him miss a train in Ireland. In 1884, an international conference in Washington chose Greenwich as the prime meridian, the line from which longitude and time would be measured. Adoption was slow – France, for example, continued to use Paris time until 1911 – but by the middle of the twentieth century most of the world had accepted the system. The railways had done more than shorten journeys: they had turned time from something read in the sky into something agreed between people.