From Sundials To Cell Phones

CBS' Lee Cowan On Mankind's Journey Through Time

(CBS)  Stonehenge was accurate to within a month or two, with its stones arranged to measure only the seasons.

By 1500 B.C., the Egyptians had narrowed it down to the day: splitting it into a dozen equal parts, twelve for daytime and twelve for at night.

They used a sundial to mark the intervals in sunlight and water trickling out of a vase to mark the intervals at night.

It was called a water clock and it became the first time measuring device that didn't depend on the heavens.

But they all had their problems.

"If you rely on a sundial, it's not going to work when there are clouds," says Andrewes. "If you rely on a water clock, it's gonna freeze in winter."

So really we can blame the invention of the clock on bad weather? Cloudy skies and cold temperatures?

"You know, this is how these things come about," says Andrewes.

By the 13th century, life was getting crowded in Europe. Urban populations were growing and so was the Roman Catholic Church, whose many orders of monks and nuns could make good use of a mechanism to alert them to their daily duties.

"Time became more crucial," notes Andrewes. "What time should you pray? What time should you eat? What time should you work?"

Medieval headscratchers eventually came up a device called an escapement, which was so revolutionary for the time that it was the technological equivalent of putting a man on the moon.

The device controlled the rotation of a toothed wheel and transmitted that energy to an oscillating bar that moved back and forth.

A simple concept - devilishly hard to put into practice - allowing a bell to be rung at the same time every day.

Very handy for the faithful committed to prayers especially for various times of day.

The new timing device soon had a name that has stuck to it ever since.

The word "clock," says Andrewes, comes from the Latin word clocka, meaning a bell, because the earliest mechanical clocks were bell-striking devices.

As rudimentary as they were, they changed everything. Andrewes says suddenly people became "time conscious" -- "time was money" -- and people began asking and answering questions that would affect everything from manufacturing to farming: What is a workday? It is from sunrise to sunset, or do you do it by the hour? And then how are you going to divide the hours? How are you going to divide the day? Where do you begin the day?

The more precise time measurement got, the more pointed those questions got. And nobody answered more of them than Christian Huygens, a Dutch scientist who took the workings of the mechanical clock and turned them on their side, becoming the inventor of the first pendulum clock, unveiled on Christmas Day in 1656.

"The early mechanical clocks would keep time to within about 15 minutes a day. The pendulum clock could keep time to within a minute a week," says Andrewes. "So it was an enormous advance."

An extraordinary advance from a scientific standpoint and also from a social standpoint.