Not knowing left from right: Malcolm Cornwall recounts two occasions when wrong-handedness and Murphy's Law combined to frustrate advances in transatlantic communications

ARE YOU right- or left-handed? Few of us have difficulty in answering. You are probably also familiar with the idea of 'handedness' in technology; for example, screws with either right- or left-handed threads. If you are a DIY enthusiast, you might have experienced the frustrating and sometimes costly result of mistaking one for the other.

Choosing - or rather, letting random chance choose - the 'wrong hand' can have dramatic outcomes. In mid-Victorian times a fortune was lost, and in the mid-20th century Britain's technological prestige was dented, as a result of wrong-handedness. These two events, both from the history of transatlantic communications and separated by almost 100 years, have intriguing similarities.

Even today, there is a danger that confusion over handedness could hinder the modern world of telecommunications via fibre-optic cables.

The first successful transatlantic telegraph cable was in operation back in 1866. This surprises many people, who underestimate the boldness and ingenuity of Victorian engineers. Indeed, the first attempt to interconnect the 1,834-mile 'short route' between Valentia in south-west Ireland and Newfoundland occurred nine years earlier. At the time, the challenge of laying such a long cable was an engineering task comparable with the Channel tunnel and, like the tunnel, the project was privately financed. A company had been formed for the purpose in 1845, but it was not until the successful operation of submarine cables across the Channel and elsewhere in the 1850s that sufficient confidence was built up for an attempt at the 'big one'.

A first attempt in 1857 failed when the cable broke, even though it was of a new design, with an outer reinforcement of heavy-gauge wire spirally wound. A second attempt was made in 1858, when the British ship Agamemnon and the US ship Niagara, set sail, each carrying half of the total length. Despite severe storms, they reached the mid-Atlantic splicing point - and there wrong-handedness struck. The cables had been manufactured by two different contractors. Unfortunately, neither had thought to agree on the direction of the 'lay' of the wire armouring. Murphy's Law assured that with but two possibilities, the outcome was the wrong one - the armouring of the cables had opposite handedness. So a twist in one section could cause the spliced-on section to unwind. By cobbling together a rigid jointing device, cable-laying was completed to the Newfoundland coast. Although messages were transmitted, signals began to fade and eventually the line went dead. The loss to investors was more than pounds 500,000.

The lessons learnt were embodied in a government report, and the result was a new type of cable, scientifically designed with the advice of eminent physicists. But it was not until 1866 that the new cable was successfully laid. With the Atlantic spanned, most of the world's capitals were soon to be linked via submarine cables. By 1901 London was at the hub of a worldwide telegraph network and, as a result, was the world's financial centre - and no doubt the fiasco of 1858 was forgotten.

Fast forward to 10 July 1962. The first transatlantic telephone cable had been laid in 1956 and less reliable radio- phone links to the United States had been achieved many years earlier. But on this day another landmark in the history of transatlantic communication was established. Live television was to be transmitted between Europe and North America via Telstar, the world's first commercial communications satellite, launched that morning. Only during part of its two and a half hour elliptical orbits would Telstar be simultaneously in range of the UK ground station at Goonhilly Downs, Cornwall, and its US counterpart in Maine, and then only for about half an hour. The slot coincided with near peak-time evening viewing, and the television science presenter Raymond Baxter warmed up the BBC audience with predictions of the wonders of British technology to come.

The British Post Office, which operated the aerials at Goonhilly, had, unlike the French, shunned the US-designed horn antennae. Instead, a simple parabolic bowl - like a large version of today's satellite dishes - was awaiting the first signals. To the embarrassment of Mr Baxter and the Goonhilly engineers, while France was seeing magnificent pictures, UK viewers could see only faint, ghostly images. The BBC was forced to switch to French television via the Eurovision link so that viewers could admire the technical quality achieved by this first demonstration of satellite TV.

The next day, Goonhilly explained the failure as an 'understandable ambiguity'. The radio signal transmitted by Telstar was of a kind known as a 'circularly polarised wave'. Ordinary television waves vibrate along a straight line, but in a circularly polarised wave the vibrations gradually change their direction so that they follow a corkscrew-like path through space. To cut out all the other waves bombarding the Goonhilly receiver, a special filter was fitted into the aerial that would allow only the corkscrew signal to be picked up. And the fatal mistake? You've guessed it - the filter had been fitted to let through signals with the twist of the screw opposite to that of the television signal] It was like trying to fit a left-handed screw into a right-handed nut. Once again, handedness had mischievously struck, this time with the loss of national face and a denting of technological pride.

With the reversal of the filter, first-class pictures were picked up the next night and the future development of British satellite television was assured - for good or ill.

Since the late 1980s, transatlantic communications have entered a new phase. Our voices are likely once more to travel under the sea, but now carried on light waves through hair-like optical fibres rather than on electric currents in copper cables. Already two fibre-optic cables connect the UK and the United States, and others are planned. Is there in future any scope for wrong-handedness to wreak its mischief once again? Ominously, future optical cables may use light waves circularly polarised, like the Goonhilly radio waves. So Murphy's Law could indeed strike again.

Malcolm Cornwall is a lecturer in physics at the University of Brighton. This is an edited version of his winning article in last months's Institute of Physics/ National Physical Laboratory science writing competition.

(Photograph omitted)