Mike Jay

The Air Loom, if Matthews revealed its existence under questioning, would now be recognised immediately as a classic paranoid delusion. But in 1797 it was something that had never been encountered before, and would emerge as the baffling leitmotif of a case that was unprecedented in almost every imaginable way.

We are now edging across the boundary - always a porous one - between self-justification and fantasy. Matthews' story is by no means a complete fantasy: we can recognise every event. But the frame of reference is somehow shrinking, and momentous world events being rewritten around the actions of a minor player.

The Bedlam that greeted James Tilly Matthews, then, was not so much a baroque spectacle of depravity as an exhausted and run-down public institution, its building falling apart and its professional image tarnished.

The French revolution, he concluded, had not produced any new principles of truths, merely a mass of examples of how things could go wrong.

It was Matthews, of course, for whom the verdict was the greatest disaster. Not only had he failed to escape from Bedlam, but the anomalies of the case made it highly unlikely that he would have the chance to appeal again. His family and friends had assembled an impeccable case, most of which had been ignored.

But, mad or sane, Matthews was a man of no ordinary persistence. He was not prepared to renounce the peace plan, any more than he would be prepared to renounce his madness a few years later. A month later he was back in France, this time for an extended stay.The optimistic dawn of his revolutionary adventures was coming to an end, and his dark night of the soul was about to begin.

Many had suspected that the political disasters of the past few years had a hidden cause. The bloodiness of the French mob rule was something unnatural, with a pitiless and inhuman progression that had never been seen before.

Up to this point, it was rare for the mad to be distinguished from the poor, the homeless, the indigent, beggars, vagabonds, petty criminals and others who were unable to fit into society or take care of themselves. It was rare, too, that they were locked up.

James Tilly Matthews was not a prophet. He was a gifted, perhaps fragile individual who suffered intensely, and for little if any reward.

We think of 1789 as the date of the French Revolution, and the storming of the Bastille as its defining event. Yet as late as halfway through 1792, most of the familiar images of the revolution had yet to occur. Louis XVI was still king, and the Assembly was negotiating a new constitutional arrangement for the monarchy, not so different from Britain's Glorious Revolution of 1688.

The French army had crowned a campaign of extraordinary successes by defeating the Austrians at Jemappes and pressing on to occupy a large swathe of Belgium and threaten Holland. For Britain, this changed everything: a French republic that spread across the North Sea coast meant the entire coastline facing Britain would be in Republican hands.

The Air Loom, for all its florid craziness, can be seen to have a function and a rationale: as a miraculous, if temporary, fix for a breaking mind, a coping strategy for a life that had become too brutally contradictory to sustain otherwise.

The Air Loom had been constructed by the Jacobins in Paris around the time of their coup d'etat in 1793. Just as they had corrupted the ideals of the Enlightenment to their despotic ends, so had they corrupted Enlightenment science. The secret of its power was pneumatic chemistry, the science of the invisible elements known as 'airs' or 'gases,' which had been developed by some of the great geniuses who had inspired the revolution.

Haslam leaves us in no doubt what we are supposed to make of Matthews' mental world: this is gibberish and nothing more.

As a pauper, the obvious destination for James Tilly Matthews was the Bethlem Hospital, already long known in popular slang as Bedlam. The principal public asylum in London, it had accepted dangerous and insane paupers as 'objects of charity' for centuries, and was proud of the claim that it had never turned anyone away.

If history is written by the victors, conspiracy theory is typically written by the losers, and there were few greater losers in the revolution than the French church and especially the Jesuits.

Come the revolution, however, mesmerism was reconceived once more. From its beginnings many had seen it as an aristocratic fad: Mesmer (by this stage long gone to Germany and Switzerland) had made a fortune from the nobility, charged the huge fee of 100 livres for admission to his Society of Universal Harmony, and even been offered a pension for life by Marie-Antoinette.

At Bow Street Magistrates' Court the essential facts were established. The man's name was James Tilly Matthews. He was a pauper of the south London parish of Camberwell. He had a wife and a young family. He appeared to be of unsound mind.