In the reader, tap any word or sentence to hear it in English,
translate it, or look up a definition.
Words to know
discrepancy
a difference between things that should match
abstaining
choosing not to vote or take part
advisory
giving advice rather than forcing a rule
translating
changing something into a different form
statutory
fixed or required by written law
crystallized
became clear and settled in a final form
timekeeping
the tracking of hours and minutes
oscillations
regular back-and-forth movements
A For most of recorded history, time was a strictly local affair. A town’s clocks were set so that noon coincided with the moment the sun crossed its meridian. Every community therefore kept a slightly different hour. The Earth rotates through 15 degrees of longitude every hour, so each degree of separation translates into a four-minute discrepancy. Bristol, for example, ran roughly ten minutes behind London. Such variation caused little inconvenience in an era when travelers moved at the pace of a horse or a sailing ship. Nobody journeyed fast enough to notice that the clocks were drifting beneath them.
B The railway and the telegraph destroyed this comfortable localism within a single generation. A train could now cross several minutes’ worth of longitude in an hour. Timetables based on local time became confusing and, on single-track lines, genuinely dangerous. Britain’s Great Western Railway responded in November 1840 by ordering all of its stations to keep London time. From 1852, the Royal Observatory at Greenwich distributed time signals by telegraph across the country. The problem was far more severe in North America, where railroads operated under dozens of competing standards. On November 18, 1883 — remembered as the “day of two noons” — the railways of the United States and Canada adopted a coordinated system of zones devised largely by the engineer William F. Allen.
C International agreement followed swiftly. In October 1884, delegates from roughly two dozen nations assembled in Washington, D.C., for the International Meridian Conference. Their task was to select a single prime meridian for the entire world. The delegates recommended the meridian passing through the Greenwich observatory by a vote of 22 to 1, with San Domingo opposed and France and Brazil abstaining. The choice was pragmatic rather than sentimental. Most of the world’s commercial shipping already navigated with charts based on Greenwich, so adopting it imposed the smallest burden on existing practice. The conference also recommended a universal day beginning at Greenwich midnight.
D The conference’s resolutions were merely advisory, and translating them into law took decades. Britain had moved ahead of the conference, making Greenwich Mean Time the legal standard for Great Britain by an act of Parliament in 1880. Elsewhere the change came more slowly. Japan aligned its clocks with a meridian nine hours ahead of Greenwich in 1888. The United States, despite hosting the conference, gave its railroad zones statutory force only with the Standard Time Act of 1918. Country by country, governments redefined legal time as an offset from Greenwich, and the familiar map of hour-wide zones gradually crystallized.
E Adoption, however, was neither smooth nor universal, and the transition produced memorable oddities. France declined to name its rival’s observatory in legislation. Instead, it defined its national time in 1911 as Paris mean time retarded by nine minutes and twenty-one seconds — Greenwich time in everything but name. The Netherlands kept its clocks roughly twenty minutes ahead of Greenwich until 1940, while Detroit clung to local solar time into the twentieth century. In Bristol, the Corn Exchange clock still carries two minute hands, one for local time and one for railway time. Several offsets defy the hourly pattern altogether: India stands five and a half hours ahead of Greenwich, and Nepal five hours and forty-five minutes.
F The final transformation removed the sun from timekeeping entirely. In 1955, the physicists Louis Essen and Jack Parry operated the first practical cesium atomic clock at Britain’s National Physical Laboratory. In 1967, the second itself was redefined as 9,192,631,770 oscillations of the cesium atom. Coordinated Universal Time, or UTC, is now computed from several hundred atomic clocks in laboratories around the world. Occasional leap seconds have been inserted since 1972 to keep it aligned with the Earth’s rotation. Time is defined by atoms and distributed by satellites, yet the zone map that governs daily life remains, at heart, a railway compromise.
Exam practice
Exam-style questions written by ESLDesk for practice.
They are not official IELTS or TOEFL questions, and ESLDesk is not affiliated with the exam providers.
True / False / Not Given
Do the following statements agree with the information in the passage?
Choose True if the statement agrees with the passage, False if it
contradicts the passage, or Not Given if the passage does not say.
In the days of purely local time, differences between town clocks caused few problems because people traveled so slowly.
Show answer
True — Para A: the variation caused little inconvenience when travelers moved at the pace of a horse or a sailing ship.
The confusion created by competing railway times was worse in Britain than in North America.
Show answer
False — Para B states the problem was far more severe in North America, where railroads ran under dozens of competing standards.
The 1884 delegates chose Greenwich for practical reasons, since ships around the world were already using charts that referred to it.
Show answer
True — Para C: the choice was pragmatic; most of the world's commercial shipping already navigated with Greenwich-based charts.
Japan was the first Asian country to set its clocks by an offset from Greenwich.
Show answer
Not Given — Para D notes Japan aligned its clocks in 1888 but never compares Japan with any other Asian country.
Once atomic clocks were introduced, official time no longer needed any adjustment to match the Earth's rotation.
Show answer
False — Para F: occasional leap seconds have been inserted since 1972 to keep UTC aligned with the Earth's rotation.
Matching Headings
The passage has 6 paragraphs, A–F.
Choose the best heading for each paragraph from the list below. There are two extra headings you will not use.
Clocks that no longer follow the sky
The slow legal spread of Greenwich time
The engineer behind North America's zones
When every town kept its own time
One reference line for the whole world
Strange exceptions to the new system
How sailors navigated before accurate clocks
The technologies that made shared time urgent
Show answer
iv. When every town kept its own time — Describes the era when each community set its clocks by its own solar noon and nobody minded the differences.
Show answer
viii. The technologies that made shared time urgent — The railway and the telegraph made local time confusing and dangerous, forcing rail companies to impose shared time.
Show answer
v. One reference line for the whole world — The 1884 Washington conference selected a single prime meridian, through Greenwich, for the entire world.
Show answer
ii. The slow legal spread of Greenwich time — The resolutions were only advisory; governments took decades to write Greenwich-based time into national law.
Show answer
vi. Strange exceptions to the new system — Lists odd holdouts and anomalies: France's renaming, the Netherlands, Detroit, Bristol's two hands, half-hour offsets.
Show answer
i. Clocks that no longer follow the sky — Atomic clocks and UTC removed the sun from timekeeping; the second is now defined by the cesium atom.
Summary Completion
Complete the summary below. Choose no more than two words
from the passage for each answer.
For centuries, every community adjusted its clocks so that 1 fell exactly when the sun stood at its highest point. Fast trains and instant messages made this patchwork unworkable, and in 1883 North American 2 introduced a common system of time zones. A year later, an international meeting agreed that the world's reference meridian should pass through 3, since most sea trade already relied on charts based on it. In the twentieth century the sun lost its role entirely, when scientists redefined the second using the 4 atom.
Show answers
noon — Para A: clocks were set so that noon coincided with the moment the sun crossed the town's meridian.
railways (also accepted: railroads) — Para B: on November 18, 1883, the railways of the United States and Canada adopted a coordinated system of zones.
Greenwich — Para C: delegates recommended the meridian passing through the Greenwich observatory by a vote of 22 to 1.
cesium — Para F: in 1967 the second was redefined as 9,192,631,770 oscillations of the cesium atom.
