INTERNATIONAL shipping was one of the most important links in the chain that connected the manufacturer to his worldwide customer base. So it is surprising that complete maritime mechanisation arrived on the scene so late.

Though steam was powering factories before the start of the 19th century and the first railways were running in the 1820s, it was not until the 1840s that steam power began to make any inroads into the dominance that sail had held for thousands of years.

And even as late as the 1890s, sailing clipper ships were still the preferred method of long-distance travel.

P>Sail had begun to come into fashion 2,000 years ago, first as an adjunct to oar power in the fighting galleys that ruled the Mediterranean, and later in its own right.

By the end of the 18th century, the science of sailing had reached a pinnacle in the Royal Navy's awesome ships-of-the-line, carrying 100 or more guns and extending British power beyond her national boundaries.

Sail helped intrepid explorers like Captain James Cook to chart the furthest reaches of the globe, and enabled merchantmen to fetch and carry the produce of the world.

In fact, although the uptake was slow, the idea of using steam to power ships came early. In America, Robert Fulton's paddle steamer Clermont was operating by 1807 - two years after Nelson's triumph at Trafalgar - and five years later Scottish engineer Patrick Bell launched his Comet.

By the middle of the 1820s, paddle steamers were a fairly common sight on rivers and short sea routes in both Britain and America.

There were several reasons why steam did not immediately sweep the seas clear of sail. The wind, of course, is free and, while the navies of the world could and did discount the cost of coal, hard-headed commercial men needed more convincing - especially considering the notorious unreliability of early steam engines and their restricted range.

At first, just as sail had been used as an addition to oared galleys, steam was used as an adjunct to sail. A ship's engine would be fired up only when the wind dropped - a belt-and-braces approach which combined economy with the reliability of sail and the ability to keep moving in any conditions.

The first non-sail-assisted Atlantic crossing was not achieved until 1833, by the Royal William, a 1,370-ton wooden-hulled steamer built in Quebec. And she spent the last 10 days of her 25-day crossing operating on only one of her two engines.

The greatest early protagonist of the steamship was the engineer Isambard Kingdom Brunel, creator of the Great Western Railway.

His Great Western of 1838 was the first steamer actually designed to cross the Atlantic, while in 1845 he constructed the Great Britain, the first propellor-driven ocean-going ship.

His greatest technical triumph was the Great Eastern of 1858, which reverted to paddlewheels and had six sail masts and five funnels.

At 10,200 tons, with the ability to carry 4,000 passengers or up to 10,000 troops, she was the largest ship afloat and remained so for the rest of the century.

Passenger services were the first commercial enterprises to convert to steam because companies had to offer speed, especially on the competitive North Atlantic run. But as steam engines became more efficient and reliable in the 1850s, cargo carriers also began to switch: so developed the ubiquitous tramp steamer of a thousand boys' stories.