The place where every second is counted

The time galleries

Royal Observatory, Greenwich

Just before stepping inside the Royal Observatory, perched on Greenwich Park Hill, I stop to take one more look at the wonderful view. A stretch of historic London, from St Paul's Cathedral to Canary Wharf, lies before me, while the Millennia Vs laser shoots across the darkening sky, marking the path of the meridian line into the distance. It is stunning and strangely romantic.

But my evening's appreciation of beauty does not end there. For inside the observatory's new time galleries are John Harrison's famous clocks, some of the most important timekeepers ever constructed. Certainly Harrison believed that H4, his fourth and final chronometer and the one that won him the longitude prize, was the most perfect and beautiful machine ever constructed. The intricacies of the cogs, the smoothness of the movement and the reassuringly solid tick from the mechanism are indeed breathtaking. H4 was the first clock capable of keeping accurate time at sea and hence enabled navigators to travel the world with a new degree of confidence.

More than two centuries after Harrison's day, my workplace at the National Physical Laboratory in South-West London might now call itself the home of time. It operates the nation's atomic clocks and broadcasts the UK time signal from Rugby.

The few lucky visitors who are invited to see our atomic clocks have to stifle their disappointment - in a room filled with banks of computers, grey and black boxes and a frenzy of wiring, one has to look very hard to find a display telling the time. Nevertheless, these clocks are beautiful to the scientists who make the tiny adjustments that keep them in tune with their counterparts around the world.

It seems that even these devices might become museum pieces in the not-too-distant future. After several decades of miniaturising atomic time to fit into a black box, the technology is reaching the limit of its potential accuracy - one second in 60 million years is not good enough for the demands of global positioning satellites, the internet, e-mail and mobile telecommunications. And so a small team at NPL, led by Patrick Gill, is developing an ion trap timepiece based on optical frequency.

The result is a device that is not only a thousandfold more accurate than the vibrating atoms used in atomic clocks, but also a simply beautiful piece of scientific equipment and a match for any of the early timepieces kept in Greenwich. You can compare them - there is an NPL ion trap on display at the observatory.

When one wanders around the four new galleries, part of a £15 million refurbishment programme at the observatory, one is reminded just how much time features in our lives and how people have tried to understand, measure and use time from prehistory to today.

There is the original speaking clock and the equipment used to generate the pips. Then there is a collection of digital wristwatches. It is difficult to pass the early plastic monstrosities without becoming nostalgic.

I remember the geek at school who had the first watch with a calculator. It was so small that one could hardly press the keys. I wonder what Harrison would have made of it.

Fiona Williams Auty is head of communications at the National Physical Laboratory, Teddington.