At the elevator doors in the corridor outside, I recognise a neighbour. He watches the brass hand on the clocklike face of the floor-indicator above the closed doors, tapping one foot impatiently. He is dressed in the uniform of a senior timetabling official. He gives a little start; the carpet must have muffled my steps.

'Good morning,' I say, as the floor-indicator sweeps slowly up. The fellow grunts. He takes out his pocket watch and looks at it; his foot taps faster. 'I don't suppose you saw those aircraft, did you?' I ask him. He looks at me oddly.

'I'm sorry?'

'The planes; the aircraft that flew past ... not ten minutes ago.'

The man stares at me. His eyes flicker as he glances at my wrist; he sees the plastic hospital bracelet. The elevator chimes. 'Oh yes,' the official says. 'Yes. The aircraft; of course.' The lift doors open smoothly. He looks round at the wood-panelled, brass-trimmed interior of the waiting elevator as I gesture for him to enter first. He inspects his watch again, mutters 'Excuse me,' and hurries off down the corridor.

I ride down alone. On a circular, leather-padded bench, I watch the rippling surface of a fish tank in one corner as the elevator rumbles down the shaft. There is a telephone by the door.

The brass instrument is heavy. I hear nothing for a moment, then a few small bleeping noises which at first sound like the odd tones I heard on my apartment's machine. These are quickly replaced by the voice of a rather surly operator. 'Yes? What do you want?' This is something of a relief.

'Oh, repairs and maintenance please.'

'What, now?'

The lift slows as it approaches the floor I want. 'No, never mind.' I hang up.

I leave the elevator on one of the upper arcade decks, where a brisk walk takes me - past small shops selling the fresh produce just arrived on the early morning goods trains - to the Inches breakfast bar. I stop on the way at a small flower stand and choose a carnation which will contrast nicely with the watch and the cravat.

The panelled, windowless walls of the breakfast bar are painted with competent but unconvincing views of green pastureland. It is a quiet, subdued place, with high ceilings and low lighting, thick carpets and thin porcelain. I am shown to my usual table, at the back. A newspaper lies folded on the table; it is concerned almost entirely with minute changes to the regulations and laws governing the running and maintenance of the bridge and its traffic, the promotions and deaths of the bridge's administrators, the generally quite remarkable boring society gatherings perpetrated by the same groups, and with some of the complicated, arcane and little-played sports and games popular with these mandarins.

I order smoked fish fillets, devilled lamb's kidneys, toast and coffee. Putting the paper aside, I gaze up at the painting on the opposite wall. It shows a sloped meadow of brilliant green, bordered with evergreens and sprinkled with bright flowers. Across a shallow valley there are tree-lined hills, edged in sunlight.

Were these scenes painted from life, or did the places exist only in the artist's head?

Coffee is brought. I have never seen a coffee plant on the bridge. My lamb's kidneys must come from somewhere, but where? On the bridge we talk of down- and up-river, and of Citywards and Kingdomwards; there must be land (would a bridge make sense without it?) but how far away?

I did all the research I could, given the limitations of both language and access which the organisation of the bridge's facilities impose on the amateur investigator, but for all my months of work, I came no closer to discovering the nature or location of either the City or the Kingdom. They remain enigmatic, placeless.

My long-abandoned requests for information are doubtless still sinking through the miasmic layers of bureaucratic ooze that represent the bridge authorities' organisational structure; I have the impression that all my original questions concerning the size of the bridge, what it is bridging, what it connects, and so on, will have been handed on, rephrased, precis'd, tidied-up, glossed, paraphrased and retransmitted so often and between so many different departments and offices that by the time they come to be considered by anybody capable of- and willing to - answer them, they will be virtually meaningless ... and that should they by some miracle survive this process just uncontaminated enough to be comprehensible, any reply, however considerately helpful and paradigmatically clear, will even more certainly have generated into utter incomprehensibility by the time it finally reaches me.

So frustrating did I find the whole investigative process that at one time I seriously considered stowing away on an express train and just going looking for the damned City, or the Kingdom. Officially my wrist band, which identifies me and informs tram conductors which hospital department to charge my ticket to, restricts my travel between two tram termini only; a range of a dozen bridge sections and about the same number of miles in each direction. Not an ungenerous allowance, but a restriction, nevertheless.

I decided not to become a stowaway; I think it is more important to recover the lost territories inside my skull than to go exploring for lost lands here. I shall stay put; when I'm cured I might go.

'Morning Orr.'

I am joined by Mr Brooke, an engineer I met in hospital. A small, dark, pressured-looking man, he sits down heavily opposite me and scowls. 'Good morning, Brooke.'

'See those damn . . .' His scowl deepens.

'Aircraft? Yes. Did you?'

'No, just the smoke. Damn cheek.'

'You disapprove.'

'Disapprove?' Brooke looks shocked. 'Not up to me to approve or disapprove, but I called up a chum of mine at Shipping and Timetabling, and they didn't know anything about these . . . aircraft. Whole thing was totally unauthorised. Heads will roll, mark my words.'

'Are there laws against what they did?'

'There's no law to permit it, Orr, that's the point. Good grief man, you can't have people going off and doing things just because they want to, just because they think something up! You have to have a... a framework.' He shakes his head. 'God, you have some odd ideas at times, Orr.'

'I'd be the last to deny it.'

Brooke orders kedgeree. We were in the same ward in hospital, and he has also been a patient of Dr Joyce's. Brooke is a senior engineer specialising in the effect of the bridge's weight on the seabed; he was injured in an accident in one of the caissons which support some of the structure's granite-shod feet. He is physically recovered now but still suffers from acute insomnia. Something about Brooke always makes me think of him as ill-lit; even in direct sunlight he always seems to be standing in shade.

'Another strange thing happened to me this morning,' I tell him. He looks wary.

'Really?' he says. I tell him about the man in the hospital bed, the television which switches itself on, and the malfunctioning phone. He seems relieved. 'Oh, that sort of thing happens all the time; crossed lines somewhere, I'll bet. You get on to Repairs and Maintenance and keep annoying them until they do something about it.'

'I shall.'

'How's that quack Joyce?'

'Still persevering with me. I've started to have some dreams, but I think they might be too ... structured for the good doctor. He practically ignored the first one. He critised me for giving up my investigations.'

Brooke tut-tuts. 'Well, Orr, he's the doctor and all that, but if I were you I wouldn't waste any more time on all these ...' He pauses, searching for a suitable severe epithet, '... questions. Not likely to get you anywhere, you know. Certainly can't see it getting your memory back. Nor will mooning like a schoolgirl over that sort of stuff.' He gestures dismissively at one of the pastoral scenes on the wall, frowning as though pointing out some unsightly blemish on the varnished panels.