From 500 feet above Vauxhall Gardens you can't see the dog turds, which is a definite improvement

Sometime in the 1830s Charles Dickens visited the famous Vauxhall Gardens by the Thames by day, and met with "disappointment at every turn; our favourite views were mere patches of paint; the fountain that had sparkled so showily by lamp-light, presented very much the appearance of a water pipe that had burst". It was a resort in decline even then, which was why the management had taken the risk of exposing its cosmetic charms to the sunlight, but it can't possibly have looked as bad as it does now, dwindled from its 12-acre spread of arbours and avenues, pavilions and parterres, to an urban dog toilet - one of those patches of ring-wormed grass and drooping trees which are optimistically described as amenities by the local council.

If Dickens went there today he'd find a small park bounded by railway arches, council blocks and terrace backs. He'd see a scuffed football pitch of orange grit, a decorative scattering of dog turds and lager cans. But he'd also see, rather astonishingly, an enormous balloon, painted with red and blue swags, swaying in its fishnet stocking and offering Londoners the chance to rise above South London by about 500 feet. It hangs there like a ghost of entertainments past.

Vauxhall has seen wonders before. In The Shows of London, a marvellous compendium of metropolitan exhibitions, Richard Altick records some of them. In 1762, 10,000 people turned out to see three Cherokee chieftains getting blind drunk on brandy, the sequel to an earlier sensational tour by Iroquois tribesmen. In 1823 visitors would have been diverted by an 80-foot high panorama of the Bay of Naples in which the volcano erupted nightly (volcanoes were very big at the time, there being regular lava flows all over town, with spectacular fireworks). Four years later the Duke of Wellington himself turned up to watch a massive reconstruction of the Battle of Waterloo, and laughed loudly at his own appearance.

Besides such special attractions there were the regular features - the fireworks, and the mechanical tableaux complete with glittering water effects made out of strips of tin. (Curiously these too had a kind of haunting persistence, until recently, in the shimmering facade of a motorcycle shop near Vauxhall Station, one of those made out of thousands of little discs of metal). There were naumachia (model naval battles) and acrobatic displays, dancing and music.

And there were also balloons. Launchings were a regular feature in Vauxhall's heyday, often accompanied by unrolling dioramas of a notional flight - from London to Paris, say. There may even have been a captive balloon ride here before, because they were extremely popular in the last century and London certainly had one. Whatever, the "Royal Vauxhall" has now given way to "Big Bob", a helium balloon which can carry up to 30 people in its doughnut-shaped basket. For the past few weeks I've been watching it from the window at Canary Wharf, rising and falling, like a giant ballcock, and the other day I finally gave in to its allure.

I told myself this was an exercise in historical empathy - a chance to experience the sort of thrills available to a Victorian Londoner. Actually I just wanted to go up in a balloon, but this sort of fraudulently scholarly alibi is not obviously applicable in the case of more twentieth-century thrills - like the bungee-jumping up-river at Battersea - so it seems wasteful not to use it when you can. Something similar has obviously occurred to the operators of Big Bob, because they use Victorian showman's print (and diction) on their leaflets - "Ascends Gracefully To A Great Height" it promises in music-hall type.

The changing definition of "great height" may be the first problem. Going up in Big Bob is perfectly interesting and, even on a smoggy summer evening of premature dusk, it lets you see quite a lot. You get an excellent aerial view of the Oval and a telephoto-lens peep at Lord Archer's penthouse in Alembic House (perhaps even his bathroom windows). It is the perfect surveillance point from which to look down on Terry Farrell's new MI6 headquarters. You can watch Eurostar trains gliding by and aircraft descending towards the Docklands airport. A lot of people wave at you. And you can't see the dog-turds from 500 feet up either, which is a definite improvement.

But a twentieth-century foot just isn't quite as high as a Victorian one would have been, in much the same way that velocity has suffered an effective devaluation over the years - 30mph used to be very fast indeed, now it's an irritating restriction. Height isn't quite as susceptible to this devaluation as speed, but height as a thrilling urban novelty surely is. Quite a lot of people have travelled in aircraft or gone up high buildings, so the attraction here is the nature of the uplift, rather than the altitude itself. In any case Big Bob feels so safe - despite the gentle tilt of the basket in the wind - that you find yourself having to provoke vertigo, like poking at a loose tooth.

Altick's book is fascinating because it reveals a surprising continuity in what tickles the public fancy - the artificial volcanoes of Las Vegas, the virtual reality rides of the Trocadero, the thrills of giant Imax screens, all have their Victorian predecessors. But Big Bob reminds you that some dimensions of thrill are inevitably eroded by time. This is not all bad news, I have realised. Because if I really want to discover how heartstopping those Victorian thrill-seekers found their ascent - simply in the interests of scholarship, you understand - I'm going to have to dive head first from a high-jib crane with elastic bands tied to my ankles