From Sundials To Cell Phones

CBS' Lee Cowan On Mankind's Journey Through Time

(CBS)  The clock, says Andrewes, began to be seen as a symbol of wisdom, goodness, temperance, industriousness, and even power.

Especially if you could build a clock to solve one of time's trickiest brainteasers.

Sailors could find their latitude by using the stars and the sun. But judging longitude was different.

"In order to determine longitude," explains Sobel, "you have to know what time it is in two places at once. That's the tricky part."

That involves measuring time at sea - and for centuries, no one had a clock that could reliably do that on the deck of a pitching ship.

Think about it: every daring sea crossing was in the end a matter of both skill and chance.

"The problem of longitude was so important," says Sobel, "that [in 1714 the British] parliament enacted a law offering £20,000 to anyone or any group of people from anywhere in the world who would come up with either a gadget or a technique that would work. They were desperate!"

John Harrison - a carpenter and self-taught clockmaker - finally came to the rescue with a modified escapement using a spring and balance wheel instead of a pendulum, to avoid sensitivity to weather and waves.

It kept time in rough seas to about one fifth of a second per day: ten times better than was required to win the prize.

Now time could be told the world over, with clocks all set by using high noon as a guidepost.

But as the world spun and decades passed, another problem presented itself: noon was slightly different for everybody.

Now that was no problem when folks were creeping across the country in a stagecoach. But when the railroads started rushing people from city to city, well, scheduling became a mess.

To standardize time, the United States established four time zones in 1883 and by the following year, the entire globe had 24 time zones - all set to Greenwich mean time.

After the steam age came the jet age, and sure enough, clocks still weren't accurate enough - not for scientists anyway.

So they came up with this: the atomic clock. The latest model is only off by a single second every 20 million years.

Atomic clocks don't tick or tock. Instead, they measure the regular vibration of atoms: the cesium-133 atom to be exact.

Turns out those regular vibrations are even more regular than the heavens themselves. For the first time, scientists could prove the earth's orbit is not constant and if we were really going to keep our clocks timed to the heavens, we needed to add a second from time to time to make up for the Earth's timely transgressions.

"The problem is, we still live on earth, we still go around the sun, and we still see the moon," says Sobel. "So no one wants those things to get too far out of synch with atomic time."

Which is why we all celebrated New Year's one second later last night. Adding that "leap" second put us all back on track.

Still, no matter how we measure it, chasing time remains an ageless daily dilemma for all us. Perhaps that's why time always seems so fleeting - and why we never seem to have enough of it.

The sundial featured in this piece was designed by William J. H. Andrewes and is located at the Pomfret School.