Clocks at Greenwich Running Down : It’s Later Than You Think for World’s Timekeeper

Times Staff Writer

Time is running out for the original global timekeepers.

The six atomic clocks at Britain’s oldest scientific institution, the Royal Greenwich Observatory, are running down, and when they stop, an era will end.

The observatory that gave the world Greenwich Mean Time, marked the prime meridian and became the ultimate reference point for anyone setting a precision timepiece, will be forced, 312 years after its inception, to ask others what time it is.

Britain was “in the forefront of timekeeping techniques until about 10 years ago,” said John D. H. Pilkington, the last permanent employee of the observatory’s once-prestigious Time Department. “But there are different national priorities now.”


In Britain, where for a decade basic research has suffered from chronic under-funding, the new national priorities exclude the $40,000 to $60,000 required to replace each of the observatory’s atomic clocks, instruments needed to keep the observatory among the 40 or so institutions in 24 countries that determine and keep the world’s time.

In many ways, the decision reflects dramatic changes in the world’s timekeeping methods as much as the extent of British government financial constraints.

The development of quartz crystal timepieces, followed by atomic clocks, has dramatically improved the accuracy of timekeeping in the last two decades.

In the 1960s, atomic clocks running off the pulse of cesium atoms defined time down to one ten-thousandth of a millionth of a second--a degree of accuracy that revealed that the Earth’s spin is not constant but gradually slowing, that the Earth is occasionally slowed even further by such things as Siberian winds, accelerates slightly in the northern autumn and has a tendency to wobble on its axis.

To compensate for these irregularities, a “leap second” has been inserted into the final minutes of most years since 1972.

Previously, clocks had merely “kept” the time after it had been confirmed by astronomers charting the Earth’s spin. Hence the expression “keeping time.”


But suddenly the centuries-old link between astronomy and the science of timekeeping was broken. The observatory’s large Isaac Newton telescope was dismantled. Under its dome today is a storage area. The Time Department, which once had as many as 30 persons, now has one--Pilkington.

The Greenwich Observatory became only one of many institutions transmitting atomic clock data to the Bureau International de l’Heure--the International Time Bureau--in Paris, which refines and averages data. But last spring, staff cuts at the observatory ended even those contributions to the International Time Bureau.

In effect, the Paris bureau has replaced Greenwich as the ultimate reference point for calculating time. Although it has no single master clock, the bureau is a focal point where the many atomic timepieces of today’s world are compared against each other, enabling their owners to make minor adjustments if necessary.

According to people associated with the Greenwich Observatory’s Time Department, rich tradition and long experience have kept this observatory the most accurate of the world’s many timekeepers.

‘Our Technique Is Better’

“Our records over the past 20 years are the most accurate,” said Anthony R. Seabrook, an observatory production engineer involved with timekeeping at Greenwich for 25 years. “Our technique is better. We know how to treat the clocks, what temperatures (and) humidity to maintain, and how to handle them. After all, we’ve been at this job for over 300 years.”

Nevertheless, the rationale behind the government’s cost-cutting decision is difficult to challenge.


Rising costs of precise time-measuring equipment coupled with the large number of institutions keeping time accurately led government planners to regard the observatory’s Time Department as a marginal investment.

Instead, the greater part of the observatory’s budget will be channeled into exploring the more exciting outer reaches of the universe. The observatory will use one of the world’s largest telescopes, which it recently installed in the Canary Islands.

In further cost-cutting moves, other departments of the observatory will be uprooted, reduced in size and relocated for the second time since World War II, to Cambridge.

Original Site Abandoned

In 1948, London’s industrial sprawl, its brighter lights and air pollution forced the observatory to abandon its original site by the Thames at Greenwich for the clearer, darker skies of rural Sussex and its present home in a 15th-Century castle at Herstmonceux.

Once the clocks stop, possibly in a matter of months, a scientific tradition will end what began three centuries ago at the instigation of King Charles II. He provided the funds that established the observatory at Greenwich in 1675.

For Britain, a seafaring nation, the quest for accurate time was closely linked to a problem of national security: solving the mystery of longitude at sea--position in the east-west sense--a goal that would perfect navigation and improve naval effectiveness.


Knowing the exact time at a fixed point on land as well as at the ship’s position enabled navigators to calculate longitudinal distance using the Earth’s rotation as a guide.

When a sea captain, largely guessing, miscalculated his longitude and ran a Royal Navy flotilla into the Scilly Isle at the cost of nearly 2,000 lives, the government established a Board of Longitude and offered a prize of 20,000 pounds for anyone who could solve the riddle of how to keep time accurately aboard ship, where pendulum clocks were useless.

Prize for London Clockmaker

It was nearly 50 years before a London clock maker named John Harrison perfected a nautical clock, or chronometer, that was accurate to within eight seconds in 24 hours--enough to win the prize.

For British ships, a clock showing Greenwich Time was soon part of a navigator’s equipment. Often it was kept under lock and key.

On land, the advent of railroads, the telegraph and increased travel in Europe and the United States brought new demands for unified time into a world where each town once kept its own time, invariably different from that of its neighbors.

Oxford, for example, was west of Greenwich and thus five minutes behind Greenwich Time; Yarmouth, on Britain’s east coast, was six minutes ahead.


As railroads imposed standard time for scheduling, the confusion mounted. In France, railroad station clocks were set to a uniform national time five minutes behind Paris, but elsewhere clocks showed whatever the local time might be, and it might be considerably different.

Six Different Time Standards

In the United States, where distances were greater, so was the chaos. In Pittsburgh around the mid-19th Century, for example, there were six different time standards for departing and arriving trains, depending on the railroad.

Local communities in several countries resisted changing “God’s time,” but gradually standardization crept in and the clocks at Greenwich grew in importance.

In October, 1833, the Royal Observatory took to hoisting a “time ball” to the top of a pole on the observatory roof and dropping it at precisely 1 p.m. Ships up and down the Thames set their clocks by it.

(What is generally accepted as world’s first public time signal still operates today--and will continue even after the atomic clocks run down).

The observatory telegraphed Greenwich Time first to railroad stations and then to post offices throughout the country. By the 1850s, most of Britain had adjusted to the Greenwich standard.


Messenger’s Pocket Watch

The observatory also instituted a service based on a messenger who, every Monday, set his pocket watch at the observatory and then made the rounds of London’s chronometer manufacturers delivering Greenwich time. Although overtaken by technology, the service lasted into the 1930s.

Since 1924, the British Broadcasting Corp.’s World Service has transmitted an hourly six-pip time signal generated by the observatory’s clocks to its listeners in 38 countries.

As world travel and trade increased, the need increased for a prime, or zero, meridian as a location to standardize international time. In 1884, representatives of 25 countries met in Washington to discuss the matter.

Delegates rejected Paris, Jerusalem, the Pyramids of Egypt and even the Bering Strait as possible sites for marking the prime meridian. They also decided against the idea of beginning the day at noon, and eventually agreed on a universal day that would begin at Greenwich at midnight and last for 24 hours.

The United States and Canada had already adopted Greenwich Mean Time as the global reference in 1883, and most European countries followed suit after the 1884 meeting. By the 1930s, Latin America and much of Africa and Asia had fallen into line.

Need for More Precise Time

Improved technology, the need for more precise positioning for such developments as high-speed radio transmissions and space flight have all pushed the need for more precise time measurements.


The pace of 20th-Century life has also generated greater public awareness of the exact time.

People on the observatory staff recall that in 1972, when they initiated the leap second, they were deluged by irate quartz watch owners wondering what had happened.

But when the observatory’s atomic clocks run down, it is unlikely that the public will ever notice.

Ship’s navigators, airline pilots and scientists will still refer to Greenwich Mean Time--the prime meridian will not move--but no one at the Greenwich Royal Observatory will have anything to do with calculating it.

“To the man on the street, there’ll be no difference,” noted the observatory’s spokesman Charles Parker. “The trains will still run on time.”