“Why?” Stern said.
“Come closer.” Gordon ran his fingers over the surface of the glass. “See these little pits? These little grayish spots? They’re small, so you’d never notice them unless you looked carefully. But they’re flaws that weren’t there before. I think the explosion blew tiny drops of hydrofluoric acid into the other room.”
“And now the glass has been etched.”
“Yes. Slightly. But if these pits have weakened the glass, then the shields may crack when they are filled with water and the glass is put under pressure. Or worse, the entire glass shield may shatter.”
“And if it does?”
“Then we won’t have full shielding around the site,” Gordon said, looking directly at Stern. “In which case, we can’t safely bring your friends back. They’d risk too many transcription errors.”
Stern frowned. “Do you have a way to test the panels? See if they’ll hold up?”
“Not really, no. We could stress-test one, if we were willing to risk breaking it, but since we have no spare panels, I won’t do that. Instead, I’m doing a microscopic polarization visual inspect.” He pointed to the technician in the corner, wearing goggles, going over the glass. “That test can pick up preexisting stress lines—which always exist in glass—and give us a rough idea of whether they’ll break. And he’s got a digital camera that is feeding the data points directly into the computer.”
“You going to do a computer simulation?” Stern said.
“It’ll be very crude,” Gordon said. “Probably not worth doing, it’s so crude. But I’ll do it anyway.”
“So what’s the decision?”
“When to fill the panels.”
“I don’t understand.”
“If we fill them now, and they hold up, then everything is probably fine. But you can’t be sure. Because one of the tanks may have a weakness that will break only after a period of pressure. So that’s an argument to fill all the tanks at the last minute.”
“How fast can you fill them?”
“Pretty fast. We have a fire hose down here. But to minimize stress, you probably want to fill them slowly. In which case, it would take almost two hours to fill all nine shields.”
“But don’t you get field bucks starting two hours before?”
“Yes—if the control room is working right. But the control room equipment has been shut down for ten hours. Acid fumes have gotten up there. It may have affected the electronics. We don’t know if it is working properly or not.”
“I understand now,” Stern said. “And each of the tanks is different.”
“Right. Each one is different.”
It was, Stern thought, a classic real-world scientific problem. Weighing risks, weighing uncertainties. Most people never understood that the majority of scientific problems took this form. Acid rain, global warming, environmental cleanup, cancer risks—these complex questions were always a balancing act, a judgment call. How good was the research data? How trustworthy were the scientists who had done the work? How reliable was the computer simulation? How significant were the future projections? These questions arose again and again. Certainly the media never bothered with the complexities, since they made bad headlines. As a result, people thought science was cut and dried, in a way that it never was. Even the most established concepts—like the idea that germs cause disease—were not as thoroughly proven as people believed.
And in this particular instance, a case directly involving the safety of his friends, Stern was faced with layers of uncertainty. It was uncertain whether the tanks were safe. It was uncertain whether the control room would give adequate warning. It was uncertain whether they should fill the tanks slowly now, or quickly later. They were going to have to make a judgment call. And lives depended on that call.
Gordon was staring at him. Waiting.
“Are any of the tanks unpitted?” Stern said.
“Yes. Four.”
“Then let’s fill those tanks now,” Stern said. “And wait for the polarization analysis and the computer sim before filling the others.”
Gordon nodded slowly. “Exactly what I think,” he said.
Stern said, “What’s your best guess? Are the other tanks okay, or not?”
“My best guess,” Gordon said, “is that they are. But we’ll know more in a couple of hours.”
06:40:22
“Good Sir André, I pray you come this way,” Guy de Malegant said with a gracious bow and a wave of his hand.
Marek tried to conceal his astonishment. When he had galloped into La Roque, he fully expected that Guy and his men would kill him at once. Instead, they were treating him deferentially, almost as an honored guest. He was now deep in the castle, in the innermost court, where he saw the great hall, already lit inside.
Malegant led him past the great hall and into a peculiar stone structure to the right. This building had windows fitted not only with wooden shutters but with windowpanes made of translucent pig bladders. There were candles in the windows, but they were outside the pig bladders, instead of inside the room itself.
He knew why even before he stepped into the building, which consisted of a single large room. Against the walls, gray fist-size cloth sacks stood heaped high on raised wooden platforms above the floor. In one corner, iron shot was piled in dark pyramids. The room had a distinctive smell—a sharp, dry odor—and Marek knew exactly where he was.
The arsenal.
Malegant said, “Well, Magister, we found one assistant to help you.”
“I thank you for that.” In the center of the room, Professor Edward Johnston sat cross-legged on the floor. Two stone basins containing mixtures of powder were set to one side. He held a third basin between his knees, and with a stone mortar, he was grinding a gray powder with a steady, circular motion. Johnston did not stop when he saw Marek. He did not register surprise at all.
“Hello, André,” he said.
“Hello, Professor.”
Still grinding: “You all right?”
“Yes, I’m okay. Hurt my leg a little.” In fact, Marek’s leg was throbbing, but the wound was clean; the river had washed it thoroughly, and he expected it to heal in a few days.
The Professor continued to grind, patiently, ceaselessly. “That’s good, André,” he said in the same calm voice. “Where are the others?”
“I don’t know about Chris,” Marek said. He was thinking of how Chris had been covered with blood. “But Kate is okay, and she is going to find the—”
“That’s fine,” the Professor said quietly, his eyes flicking up to Sir Guy. Changing the subject, he nodded to the bowl. “You know what I’m doing, of course?”
“Incorporating,” Marek said. “Is the stuff any good?”
“It’s not bad, all things considered. It’s willow charcoal, which is ideal. The sulfur’s fairly pure, and the nitrate’s organic.”
“Guano?”
“That’s right.”
“So, it’s about what you’d expect,” Marek said. One of the first things Marek had studied was the technology of gunpowder, a substance that first became widely employed in Europe in the fourteenth century. Gunpowder was one of those inventions, like the mill wheel or the automobile, that could not be identified with any particular person or place. The original recipe—one part charcoal, one part sulfur, six parts saltpeter—had come from China. But the details of how it had arrived in Europe were in dispute, as were the earliest uses of gunpowder, when it was employed less as an explosive than as an incendiary. Gunpowder was originally used in weapons when firearms meant “arms that make use of fire,” and not the modern meaning of explosive projectile devices such as rifles and cannon.
This was because the earliest gunpowders were not very explosive, because the chemistry of the powder was not understood, and because the art hadn’t been developed yet. Gunpowder exploded when charcoal and sulfur burned extremely rapidly, the combustion enabled by a rich source of oxygen—namely nitrate salts, later called
saltpeter. The most common source of nitrates was bat droppings from caves. In the early years, this guano was not refined at all, simply added to the mixture.
But the great discovery of the fourteenth century was that gunpowder exploded better when it was ground extremely fine. This process was called “incorporation,” and if properly done, it yielded gunpowder with the consistency of talcum powder. What happened during the endless hours of grinding was that small particles of saltpeter and sulfur were forced into microscopic pores in the charcoal. That was why certain woods, like willow, were preferred; their charcoal was more porous.
Marek said, “I don’t see a sieve. Are you going to corn it?”
“No.” Johnston smiled. “Corning’s not discovered yet, remember?”
Corning was the process of adding water to the gunpowder mixture, making a paste that was then dried. Corned powder was much more powerful than dry-mixed powder. Chemically, what happened was that the water partially dissolved the saltpeter, allowing it to coat the inside of the charcoal micropores, and in the process, it carried the insoluble sulfur particles inside, too. The resulting powder was not only more powerful but also more stable and long-lasting. But Johnston was right; corning was only discovered around 1400—roughly forty years from now.
“Should I take over?” Marek said. Incorporating was a lengthy process; sometimes the grinding went on for six or eight hours.
“No. I’m finished now.” The Professor got to his feet, then said to Sir Guy, “Tell my Lord Oliver that we are ready for his demonstration.”
“Of Greek Fire?”
“Not precisely,” Johnston said.
:
In the late afternoon sun, Lord Oliver paced impatiently along the massive wall of the outer perimeter. The battlement was more than fifteen feet wide here, dwarfing the row of cannon nearby. Sir Guy was with him, as well as a sullen Robert de Kere; they all looked up expectantly when they saw the Professor. “Well? Are you at last prepared, Magister?”
“My Lord, I am,” the Professor said, walking with two of his bowls, one under each arm. Marek carried a third bowl, in which the fine gray powder had been mixed with a thick oil that smelled strongly of resin. Johnston had told him not to touch this mixture on any account, and he needed no reminding. It was a disagreeable, reeking goo. He also carried a bowl of sand.
“Greek Fire? Is it Greek Fire?”
“No, my Lord. Better. The fire of Athenaios of Naukratis, which is called ‘automatic fire.’”
“Is that so?” Lord Oliver said. His eyes narrowed. “Show me.”
Beyond the cannon was the broad eastern plain, where the trebuchets were being assembled in a line. They were just out of shot range, two hundred yards away. Johnston set his bowls on the ground between the first two cannon. The first cannon he loaded with a sack from the armory. He then placed a thick metal arrow with metal vanes into the cannon. “This is your powder, and your arrow.”
Turning to the second cannon, he carefully poured his finely ground gunpowder into a sack, which he stuffed into the cannon mouth. Then he said, “André, the sand, please.” Marek came forward and set the basin of sand at the Professor’s feet.
“What is that sand for?” Oliver asked.
“A precaution, my Lord, against error.” Johnston picked up a second metal arrow, handling it gingerly, holding it only at each end and gently inserting it into the cannon. The tip of the arrow was grooved, the grooves filled with thick brown acrid paste.
“This is my powder, and my arrow.”
The gunner handed the Professor a thin stick of wood, glowing red at one end. Johnston touched the first cannon.
There was a modest explosion: a puff of black smoke, and the arrow flew onto the field, landing a hundred yards short of the nearest trebuchet.
“Now my powder, and my arrow.”
The Professor touched the second cannon.
There was a loud explosion and a blast of dense smoke. The arrow landed alongside a trebuchet, missing it by ten feet. It lay in the grass.
Oliver snorted. “Is that all? You will forgive me if I have—”
Just then, the arrow burst into a circle of fire, spitting blobs of flame in all directions. The trebuchet immediately caught fire, and men on the field ran forward, carrying the horses’ water bags to put it out.
“I see . . .,” Lord Oliver said.
But water seemed to spread the fire, not quench it. With each new dousing, the flames leapt higher. The men stepped back, confused. In the end, they watched helplessly as the trebuchet burned before them. In a few moments, it was a mass of charred, smoking timbers.
“By God, Edward and Saint George,” Oliver said.
Johnston gave a small bow, smiled.
“You have twice the range and an arrow that alights itself—how?”
“The powder is ground fine and so explodes more fiercely. The arrows are filled with oil, sulfur and quicklime, mixed with tow. Touching any water makes them catch fire—here it’s the dampness of the grass. That is why I have a basin of sand, should the slightest bit of the mixture be upon my fingers and start to burn from the moisture of my hands. It is a most delicate weapon, my Lord, and delicate to handle.”
He turned to the third basin, near Marek.
“Now, my Lord,” Johnston said, picking up a wooden stick, “I pray you observe what follows.” He dipped the stick into the third bowl, coating the tip with the oily, foul-smelling mixture. He held the stick in the air. “As you see, there is no change. And there shall be no change for hours, or days, until . . .” With the theatricality of a magician, he splashed the stick with a small cup of water.
The stick made a hissing sound, began to smoke, and then burst into flames as the Professor held it. The flame was a hot-orange color.
“Ah,” Oliver said, sighing with pleasure. “I must have a quantity of this. How many men do you require to grind and make your substance?”
“My Lord, twenty will do. Fifty is better.”
“You shall have fifty, or more as you will,” Oliver said, rubbing his hands. “How quickly can you make it?”
“The preparation is not lengthy, my Lord,” Johnston said, “but it cannot be done in haste, for it is dangerous work. And once made, the substance is a hazard within your castle, for Arnaut is certain to attack you with flaming devices.”
Oliver snorted. “I care nothing for that, Magister. Make it now, and I shall put it to use this very night.”
:
Back in the arsenal, Marek watched as Johnston arranged the soldiers in rows of ten, with a grinding bowl in front of each man. Johnston walked down the rows, pausing now and again to give instructions. The soldiers were grumbling about what they called “kitchen work,” but Johnston told them that these were, in his words, the herbs of war.
It was several minutes later when the Professor came over to sit in the corner with him. Watching the soldiers work, Marek said, “Did Doniger give you that speech, about how we can’t change history?”
“Yes. Why?”
“It seems like we’re giving Oliver a lot of help to defend his castle against Arnaut. Those arrows are going to force Arnaut to push his siege engines back—too far back to be effective. No siege engines, no assault on the fortress. And Arnaut won’t play a waiting game. His men want quick scores—all the free companies do. If they can’t take a castle right away, they move on.”
“Yes, that’s true. . ..”
“But according to history, this castle falls to Arnaut.”
“Yes,” Johnston said. “But not because of a siege. Because a traitor lets Arnaut’s men in.”
“I’ve been thinking about that, too,” Marek said. “It doesn’t make sense. There are too many gates in this castle to open. How could a traitor possibly do it? I don’t think he could.”
Johnston smiled. “You think we might be helping Oliver keep his castle, and so we’re changing history.”
“Well. I’m just wondering.”
Marek w
as thinking that whether or not a castle fell was actually a very significant event, in terms of the future. The history of the Hundred Years War could be seen as a series of key sieges and captures. For instance, a few years from now, brigands would capture the town of Moins, at the mouth of the Seine. In itself, a minor conquest—but it would give them control of the Seine, allowing them to capture castles all the way back to Paris itself. Then there was the matter of who lived and who died. Because more often than not, when a castle fell, its inhabitants were massacred. There were several hundred people inside La Roque. If they all survived, their thousands of descendants could easily make a different future.
“We may never know,” Johnston said. “How many hours have we got left?”
Marek looked at his bracelet. The counter said 05:50:29. He bit his lip. He had forgotten that the clock was ticking. When he had last looked, there were almost nine hours; there had seemed to be plenty of time. Six hours didn’t sound quite so good.
“Not quite six hours,” Marek said.
“And Kate has the marker?”
“Yes.”
“And where is she?”
“She went to find the passage.” Marek was thinking that it was now late afternoon; if she found the passage, she could easily make her way inside the castle in two or three hours.
“Where did she go to find the passage?”
“The green chapel.”
Johnston sighed. “Is that where Marcel’s key said that it was?”
“Yes.”
“And she went alone?”
“Yes.”
Johnston shook his head. “No one goes there.”
“Why?”
“Supposedly, the green chapel is guarded by an insane knight. They say his true love died there and that he lost his mind with grief. He’s imprisoned his wife’s sister in a nearby castle, and now he kills anybody who comes near the castle, or the chapel.”
“Do you think all that’s true?” Marek said.
Johnston shrugged. “No one knows,” he said. “Because no one has ever come back alive.”