“Creak creak! Creak creak!” Babbage observed. “Abysmal racket! On and on it goes. And all evening, the rain on the windows! Pitter-patter! Pitter-patter! How is a man supposed to think? I say, drink up, Burton! What on earth's the matter with you?”

Burton gulped at his brandy. The edge of the glass rattled against his teeth. He pulled the stained handkerchief from his pocket and used it to wipe the blood from his face, dabbing at the cut on his nose.

He sighed, threw the reddened square of cotton into the fire, and muttered: “Malaria.”

“My dear fellow, I'm so sorry! Is there anything I can do?” Babbage asked.

“You could explain, sir.”

“I can explain, Sir Richard, and when I do, I'm afraid you'll find that your pursuit of Brunel and your wanton destruction of three of my probability calculators was a grave misjudgement.”

“My actions were prompted by the fact that Brunel, the great engineer, seems to have stooped to common burglary.”

“I can assure you there was nothing common about it; that I was willing to sacrifice one of my calculators as a decoy is indication enough of that, don't you think? Let me ask you a question: does the theft of diamonds qualify as a crime when millions of people-in fact, the entire Empire-will benefit from it? Before you answer, may I remind you that a similar question is frequently employed by the British government to justify the pillaging of entire countries?”

Burton held up a hand. “Stop. I myself have argued that the spread of so-called civilisation is little more than invasion and suppression, looting and enslavement, but for the life of me I can't see how it relates to the squalid burglarising of a diamond dealer's shop!”

Babbage chuckled. “There you go again. Two men crowbarring a door and coshing a policeman, that I will accept as squalid, but a mechanised genius leading three clockwork probability instruments? Tut-tut, Sir Richard! Tut-tut!”

“Answer the-” Burton stopped and groaned as a tremor overwhelmed him. The glass dropped from his hand and shattered on the edge of the hearth. Babbage flinched at the noise, then recovered himself and made to get up. Burton stopped him with a wave of a hand.

“Don't! I'm all right! So tell me, how does the good of the Empire relate to tonight's burglary?”

The Steam Man clanked into action, moving back to the drinks cabinet.

“I must share with you a vision of the future,” Babbage said. “I want to tell you what is possible-the kind of world we can start building immediately, providing I survive.”

“The diamonds have something to do with your survival? I don't understand.”

“You will.”

Burton took the replacement drink offered by Brunel.

The Steam Man resumed his former position. A small hatch flipped open in the front of his body and a pliers-like appendage reached in and pulled out a long, thick cigar. The hatch closed and the roll of tobacco was fitted into a small hole located a few inches beneath the bellows. Another arm rose and the blowtorch at its end ignited and lit the cigar. The bellows rose and fell. The cigar pumped blue smoke into the air.

Old habits die hard.

Burton sipped at his drink. It was gin. Good choice.

Babbage leaned forward. “Burton, what if there was no longer a requirement for the working classes?”

The king's agent looked down at his shoes, which were steaming before the fire.

“Keep talking,” he said. He felt weirdly disjointed, as if the world he inhabited were something he might awaken from.

“Imagine this: from one end of the Empire to the other, mechanical brains control the day-to-day necessities of human life. They cook our food. They clean our homes. They sweep our chimneys. They work in our factories. They deliver our goods. They monitor and maintain our infrastructure. They serve us absolutely, unquestioningly, uncomplainingly-and require absolutely nothing in return!”

“You mean the babbage devices?” Burton queried, his voice thick and slurring.

“Pah! The probability devices are mere prototypes. They are nothing compared to what I can achieve-if I live!”

“If you live,” Burton echoed. “And how do you propose to do that, old man?”

“Come with me.”

Babbage pushed himself out of the chair, took a walking stick from beside it, and shuffled out beyond the screens.

Weakly, Burton retrieved his cane and followed.

With a whir, a clank, and a plume of steam, Brunel fell into pace behind them.

They crossed to the centre of the workshop, where a plinth stood, draped with a thin cloth.

“Please,” Babbage said to Brunel.

The Steam Man extended an arm and pulled the material away.

Burton looked bemusedly at an intricate contraption of brass; a fantastic array of cogwheels, springs, and lenses, all contained within a brain-shaped case. It was delicate, confusing, and strangely beautiful.

“A babbage?” he asked.

“Much more than that. It is my future,” the scientist responded. “And thus, also the future of the British Empire.”

Burton leaned on his cane and wished Detective Inspector Trounce and his men would hurry up.

“How so?”

The elderly scientist gently brushed his hand over the device.

“This is my latest creation,” he said. “A probability calculator designed to employ information held in an electrical field.”

“What information?”

“Everything in here,” Babbage replied, tapping the side of his cranium with a bony forefinger.

The king's agent shook his head. “No. The brain's electrical activity is so subtle as to be immeasurable,” he said. “Furthermore, the brain is mortal, not mechanical-when it dies, so does the field.”

“As far as measurement goes, you are wrong. With regard to death, you are right. However, there's something you haven't taken into consideration. Would you show us, please, Brunel?”

Isambard Kingdom Brunel lowered himself and placed the jewel cases on the floor. There were six of them, all removed from Brundleweed's safe. The Steam Man's arms flexed. Clamps held the cases steady while fine saw blades slid through their locks. Gripping devices took hold and pulled the containers open. Five of them were pushed aside. Pincers moved forward into the sixth. One by one, five large black stones were separated from the rest.

“The Cambodian Choir Stones!” Babbage announced.

“What about them?” asked Burton, impatiently. His eyelids felt heavy and his legs weak.

“My greatest technical challenge, Sir Richard, has not been the gathering, processing, and dissemination of information, but the storage of it. It is relatively easy to make a machine that thinks, but to make a machine that remembers -that is quite another thing. Pass the gemstones to our guest, Brunel.”

The famous engineer obeyed, dropping the black diamonds one by one into Burton's extended palm. The king's agent looked at them closely, struggling to keep his eyes focused.

“You are holding in your hand the solution to the problem,” Babbage said. “These diamonds were retrieved from a temple in Cambodia by a Frenchman, Lieutenant Marie Joseph Francois Garnier. There were seven in total. They've been known in that country as the Choir Stones since their discovery in 1837 on account of the fact that they occasionally emit a faint musical hum.

“Francois Garnier gave two of the diamonds to his colleague, Jean Pelletier, and kept the remaining five for himself. Pelletier happened to be a committed Technologist. He knew we were on the lookout for such stones. We'd heard that something of the sort existed and suspected they might possess unique qualities. When he brought his two to my attention, I experimented with them and was intrigued by the possibilities offered by their rather unusual crystalline structure. I made a prototype device into which to fit them. Unfortunately, before I finished my work, Pelletier suffered a heart attack, and when his body was found there was no sign of the stones. No doubt a member of his household staff made off with them. You can't trust these lowly types. My prototype was useless to me without them, so I gave it to Darwin, who had it fitted to a man I believe you are acquainted with-John Speke.”