THE EARLIEST form of time keeping was the shadow-clock - a primitive form of sundial used in ancient Egypt in circa 1500BC.

The first "watches" were made in Nuremberg. Called "Nuremberg eggs" because of their bulky shape, the watches were carried by the wealthy upper classes more as a form of decoration, because they were poor time keepers.

The pocket watch dates back to the 17th century. It was usually fitted with a chain holding the key to wind it up. There is also evidence that watches were worn around the arm and wrist at that time, but pocket watches were the primary source of mobile time keeping until the early 20th century.

Rolex (founded 1905) produced the first officially recognised "wrist chronometer" in about 1910. Artillery officers in the First World War found wearing a pocket watch on the wrist far more practical and the first prototypes were small watches held in leather cups on a wrist strap. After the war the idea caught on with the public.

In 1922 John Harwood, a London watchmaker, invented a self-winding watch and by 1926 Rolex had designed the first waterproof watch, the "Oyster". In 1956 the Hamilton Watch Company announced it had produced the first electric watches containing a power cell that produced enough energy to run them for a year. The Pulsar quartz analogue watch with a light-emitting diode display (l.e.d.) was introduced in 1971. The early Seventies heralded an improved form of display - the "liquid crystal display" that allowed the time to be seen on the face continuously, unlike the previous l.e.d. which only displayed the time once a button was pressed.

Introduced 15 years ago, Swatch helped start the trend of timepieces created for fashion as well as function, introducing a seasonal collection of new styles twice a year.

Wrist-watch trends in the late 20th century focus on adaptability and innovative technology. Watches for deep-sea divers are at the cutting edge of watch design, with brands such as G-Shock and Seiko creating watches that are becoming more futuristic.

For the ultimate in precision time keeping, the new atomic clock, developed at the British Physical Laboratory, is an almost absolute measure of time. Shaped like a computer hard-drive with a digital read-out display, wrist- watches have been designed to pick up the time transmitted from the European atomic clock in Germany. With atomic power now available on your wrist, time is ticking away to find the next horological discovery...