Key to unlocking mobility of hurricanes

For centuries, they were thought of as discrete events

For centuries, they were thought of as discrete events. No one had the means to see the bigger picture, and to recognise that a tempest which sank a fleet in the Antilles might be the same one that several days later caused tragedy in Florida.

It was Benjamin Franklin, who made so many other seminal discoveries in science, who first provided the key to the mobile nature of a hurricane.

In November 1743, a violent north-easterly storm, the fringes of a former Caribbean hurricane, hit Franklin's home in Philadelphia and inconveniently obscured his view of an eclipse.

Franklin learned later that the eclipse had been clearly visible in Boston before the storm arrived. From this he realised that the zone of north-easterly winds must have moved from south to north, from Philadelphia to Boston, in the opposite direction to the wind itself.

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Six years later, Franklin verified his theory by tracking the progress of another hurricane from North Carolina along the eastern seaboard to New England, establishing the notion that a storm moved steadily along some predetermined path.

As with so many notions conjured up by Franklin, it was an idea that was years ahead of its time; it was not until the middle of the 19th century that it was commonly accepted that all storms are actually circular wind systems, and that they move bodily from one place to another.

But what was it like to experience a hurricane? A near contemporary of Franklin, the US Secretary of the Treasury, Alexander Hamilton, survived one in the Caribbean and lived to tell the tale: "Good God! What horror and destruction! It seemed as if the total dissolution of the natural world was taking place.

"The roaring of the sea and wind, fiery meteors flying about in the air, the prodigious glare of almost perpetual lightning, the crash of falling houses and the ear-piercing shrieks of the distressed, were sufficient to strike astonishment into Angels."

Nearer to our own day, Joseph Conrad's description in Typhoon suggests that he, too, had the experience: "A ragged mass of clouds hanging low, the lurch of the long outline of the ship, the black figures of the men caught on the bridge-head forward as if petrified in the act of butting - the darkness palpitated down upon all this, and then the real thing came at last.

"It was something formidable and swift, like the sudden smashing of a vial of wrath. It seemed to explode all round the ship with an overpowering concussion and a rush of great waters, as if an immense dam had been suddenly blown up to windward."