DESPITE those romantic tales about kitchen ranges and boiling kettles, James Watt did not invent the steam engine - he just improved a design that had been around for more than half a century.

The power of steam had been recognised since the time of the Ancient Greeks, when in the second century BC, Hero of Alexandria used a kind of turbine to produce what many must have thought of as magical events, such as the automatic opening of temple doors.

But the knowledge was lost with the demise of Greek civilisation, and it did not surface again until the middle of the sixteenth century. Then, apparently, in the year 1543, a Spanish naval captain called Blasco de Garay demonstrated a steam-powered ship to amazed onlookers at Barcelona Harbour.

The 200-ton Trinity reputedly featured a large copper boiler powering a pair of paddle wheels - but nothing more was heard of it, and the dream of steam power slumbered on for nearly another century.

Edward Somerset, son of the first Marquis of Worcester, finally put steam on the map just before the start of the English Civil War in 1641. Although many historians refuse to recognise the fact, there is compelling evidence that Somerset had a steam pump up and running before hostilities broke out.

He installed it in the keep of the family seat, Raglan Castle in South Wales, and the story goes that it was used as a 'weapon of mass distraction' to frighten Parliamentary forces.

Apparently, when Roundhead forces arrived at the castle to demand its surrender, the order was given to start the steam pump. As it hissed and roared into life, someone shouted "The Lions have got loose," and the Parliamentarians, knowing the marquis kept a menagerie at the castle, fled for their lives.

Sadly, the Worcesters' huge fortune was squandered supporting an ungrateful Royal Family, Somerset - by now the second Marquis - fled to the continent at the end of the war, and when he returned he was too old and impoverished to turn his idea into a saleable proposition.

Somerset's pump used steam in two ways. First, it was allowed into a sealed chamber which was then cooled. This created a vacuum, which sucked open a valve connecting to a pipe with its end in the water which was to be pumped.

Water rushed up the pipe into the empty chamber and, pressure then being equalised, the valve closed of its own accord. At this point, more steam was admitted and the water in the chamber was forced upwards through another valve into the exit pipe, to a height of perhaps 40 feet.

Somerset never made a penny out of his machine, but the idea was taken up more than half a century later by a Devon man called Thomas Savery, who probably read about it in Somerset's 1655 book. The book's full title is too long to repeat, but it is known universally as The Century, and Savery