'Phase of the Moon valve,' said Hubert promptly.

'The moon affects how money moves around?'

'We don't know. It might. The weather certainly does.'

'Really?'

'Certainly!' Hubert beamed. 'And we're adding fresh influences all the time. Indeed, I will not be satisfied until my wonderful machine can completely mimic every last detail of our great city's economic cycle!' A bell rang, and he went on: 'Thank you, Igor! Let it go!'

Something clanked, and coloured waters began to foam and slosh along the bigger pipes. Hubert raised not only his voice but also a long pointer.

'Now, if we reduce public confidence in the banking system — watch that tube there — you will see here a flow of cash out of the banks and into Flask Twenty-eight, currently designated the Old Sock Under the Mattress. Even quite rich people don't want their money outside their control. See the mattress getting fuller, or perhaps I should say… thicker?'

'That's a lot of mattresses,' Moist agreed.

'I prefer to think of it as one mattress a third of a mile high.'

'Really?' said Moist.

Slosh! Valves opened somewhere, and water rushed along a new path.

'Now see how bank lending is emptying as the money drains into the Sock?' Gurgle! 'Watch Reservoir Eleven, over there. That means business expansion is slowing… there it goes, there it goes…' Drip!

'Now watch Bucket Thirty-four. It's tipping, it's tipping… there! The scale on the left of Flask Seventeen shows collapsing businesses, by the way. See Flask Nine beginning to fill? That's foreclosures. Job losses is Flask Seven… and there goes the valve on Flask Twenty-eight, as the socks are pulled out.' Flush! 'But what is there to buy? Over here we see that Flask Eleven has also drained…' Drip.

Except for the occasional gurgle, the aquatic activity subsided.

'And we end up in a position where we can't move because we're standing on our own hands, as it were,' said Hubert. 'Jobs vanishing, people without savings suffering, wages low, farms going back to wilderness, rampaging trolls coming down from the mountains—'

'They're here already,' said Moist. 'Some of them are even in the Watch.'

'Are you sure?' said Hubert.

'Yes, they've got helmets and everything. I've seen them.'

'Then I expect they'll be wanting to rampage back to the mountains,' said Hubert. 'I think I would if I were them.'

'You believe all that could really happen?' said Moist. 'A bunch of tubes and buckets can tell you that?'

'They are correlated to events very carefully, Mr Lips wick,' said Hubert, looking hurt. 'Correlation is everything. Did you know it is an established fact that hemlines tend to rise in times of national crisis?'

'You mean—?' Moist began, not at all certain how the sentence was going to end.

'Women's dresses get shorter,' said Hubert.

And that causes a national crisis? Really? How high do they go?'

Mr Bent coughed a leaden cough. 'I think perhaps we should go, Mr Lipwig,' he said. 'If you have seen all you want, no doubt you are in a hurry to leave.' There was a slight emphasis on 'leave'.

'What? Oh… yes,' said Moist. 'I probably should be getting along. Well, thank you, Hubert. It has been an education and no mistake.'

'I just can't get rid of the leaks,' said the little man, looking crestfallen. 'I swear that every joint is watertight, but we never end up with the same amount of water that we started with.'

'Of course not, Hubert,' said Moist, patting him on the shoulder. 'And that's because you're close to achieving perfection!'

'It is?' said Hubert, wide-eyed.

'Certainly. Everyone knows that at the end of the week you never have quite as much money as you think you should. It's a well-known fact!'

The sunrise of delight dawned on Hubert's face. Topsy was right, Moist told himself. I am good with people.

'Now demonstrated by the Glooper!' Hubert breathed. 'I shall write a paper on it!'

'Or you could write it on paper!' said Moist, shaking him warmly by the hand. 'Okay, Mr Bent, let us tear ourselves away!'

When they were walking up the main stairs Moist said: 'What relation is Hubert to the current chairman?'

'Nephew,' said Bent. 'How did you—?'

'I'm always interested in people,' said Moist, smiling to himself. 'And there's the red hair, of course. Why does Mrs Lavish have two crossbows on her desk?'

'Family heirlooms, sir,' lied Bent. It was a deliberate, flagrant lie, and he must have meant it to be seen as such. Family heirlooms. And she sleeps in her office. All right, she's an invalid, but people usually do that at home.

She doesn't intend to step out of the room. She's on guard. And she's very particular about who comes in.

'Do you have any interests, Mr Bent?'

'I do my job with care and attention, sir.'

'Yes, but what do you do in the evenings?'

'I double-check the day's totals in my office, sir. I find counting very… satisfying.'

'You're very good at it, yes?'

'Better than you can imagine, sir.'

'So if I save ninety-three dollars forty-seven a year for seven years at two and a quarter per cent, compound, how—'

'$835.13 calculated once annually, sir,' said Bent calmly.

Yes, and twice you've known the exact time, thought Moist. And you didn't look at a watch. You are good with numbers. Inhumanly good, perhaps…

'No holidays?' he said aloud.

'I did a walking tour of the major banking houses of Uberwald last summer, sir. It was most instructive.'

'That must have taken weeks. I'm glad you felt able to tear yourself away!'

'Oh, it was easy, sir. Miss Drapes, who is the senior clerk, sent a coded clacks of the day's business to each of my lodging houses at the close of business every day. I was able to review it over my after-dinner strudel and respond instantly with advice and instructions.'

'Is Miss Drapes a useful member of staff?'

'Indeed. She performs her duties with care and alacrity.' He paused. They were at the top of the stairs. Bent turned and looked directly at Moist. 'I have worked here all my life, Mr Lipwig. Be careful of the Lavish family. Mrs Lavish is the best of them, a wonderful woman. The others… are used to getting their own way.'

Old family, old money. That kind of family. Moist felt a distant call, like the song of the skylark. It came back to taunt him every time, for example, he saw an out-of-towner in the street with a map and a perplexed expression, crying out to be relieved of his money in some helpful and hard-to-follow way.

'Dangerously so?' he said.

Bent looked a little affronted at this directness. 'They are not at home to disappointment, sir. They have tried to declare Mrs Lavish insane, sir.'

'Really?' said Moist. 'Compared to who?'

The wind blew through the town of Big Cabbage, which liked to call itself the Green Heart of the Plains.

It was called Big Cabbage because it was home to the Biggest Cabbage in the World, and the town's inhabitants were not very creative when it came to names. People travelled miles to see this wonder; they'd go inside its concrete interior and peer out through the windows, buy cabbage-leaf bookmarks, cabbage ink, cabbage shirts, Captain Cabbage dolls, musical boxes carefully crafted from kohlrabi and cauliflower that played 'The Cabbage Eater's Song', cabbage jam, kale ale, and green cigars made from a newly developed species of cabbage and rolled on the thighs of local maidens, presumably because they liked it.

Then there was the excitement of BrassicaWorld, where very small children could burst into terrified screams at the huge head of Captain Cabbage himself, along with his friends Cauliflower the Clown and Billy Broccoli. For older visitors there was of course the Cabbage Research Institute, over which a green pall always hung and downwind of which plants tended to be rather strange and sometimes turned to watch you as you passed.