Not surprisingly, Elfric objected. "He was never a member of the guild because he did not finish his apprenticeship."
"Because he wouldn't marry your daughter, you mean," said one of the men, and they all laughed. Merthin took a few moments to identify the speaker: it was Bill Watkin, the house builder, the black hair around his bald dome now turning gray.
"Because he is not a craftsman of the required standard," Elfric persisted stubbornly.
"How can you say that?" Mark protested. "He has built houses, churches, palaces--"
"And our bridge, which is cracking after only eight years."
"You built that, Elfric."
"I followed Merthin's design exactly. Clearly the arches are not strong enough to bear the weight of the roadbed and the traffic upon it. The iron braces I have installed have not been sufficient to prevent the cracks widening. Therefore I propose to reinforce the arches either side of the central pier, on both bridges, with a second course of masonry, doubling their thickness. I thought this subject might come up tonight, so I have prepared estimates of the cost."
Elfric must have started to plan this attack the moment he heard that Merthin was back in town. He had always seen Merthin as an enemy: nothing had changed. However, he had failed to understand the problem with the bridge, and that gave Merthin his chance.
He spoke to Jeremiah in a low voice. "Would you do something for me?"
"After all you did for me? Anything!"
"Run to the priory now and ask to speak to Sister Caris urgently. Tell her to find the original drawing I made for the bridge. It should be in the priory library. Bring it here right away."
Jeremiah slipped out of the room.
Elfric went on: "I must tell guildsmen that I have already spoken to Prior Godwyn, who says the priory cannot afford to pay for this repair. We will have to finance it, as we financed the original cost of building the bridge, and be repaid out of penny tolls."
They all groaned. There followed a long and bad-tempered discussion about how much money each member of the guild should put up. Merthin felt animosity building up toward him in the room. This was undoubtedly what Elfric had intended. Merthin kept looking at the door, willing Jeremiah to reappear.
Bill Watkin said: "Maybe Merthin should pay for the repairs, if it's his design that's at fault."
Merthin could not stay out of the discussion any longer. He threw caution to the winds. "I agree," he said.
There was a startled silence.
"If my design has caused the cracks, I'll repair the bridge at my own expense," he went on recklessly. Bridges were costly: if he was wrong about the problem, it could cost half his fortune.
Bill said: "Handsomely said, I'm sure."
Merthin said: "But I have something to say, first, if guildsmen will permit." He looked at Elfric.
Elfric hesitated, obviously trying to think of a reason for refusing; but Bill said: "Let him speak," and there was a chorus of assent.
Elfric nodded reluctantly.
"Thank you," said Merthin. "When an arch is weak, it cracks in a characteristic pattern. The stones at the top of the arch are pressed downwards, so that their lower edges splay apart, and a crack appears at the crown of the arch on the intrados--the underside."
"That's true," said Bill Watkin. "I've seen that sort of crack many a time. It's not usually fatal."
Merthin went on: "This is not the type of cracking you're seeing on the bridge. Contrary to what Elfric said, those arches are strong enough: the thickness of the arch is one-twentieth of its diameter at the base, which is the standard proportion, in every country."
The builders in the room nodded. They all knew that ratio.
"The crown is intact. However, there are horizontal cracks at the springing of the arch either side of the central pier."
Bill spoke again. "You sometimes see that in a quadripartite vault."
"Which this bridge is not," Merthin pointed out. "The vaults are simple."
"What's causing it, then?"
"Elfric did not follow my original design."
Elfric said: "I did!"
"I specified a pile of large, loose stones at both ends of the piers."
"A pile of stones?" Elfric said mockingly. "And you say that's what was going to keep your bridge upright?"
"Yes, I do," Merthin said. He could tell that even the builders in the room agreed with Elfric's skepticism. But they did not know about bridges, which were different from any other kind of building because they stood in water. "The piles of stones were an essential part of the design."
"They were never in the drawings."
"Would you like to show us my drawings, Elfric, to prove your point?"
"The tracing floor is long gone."
"I did a drawing on parchment. It should be in the priory library."
Elfric looked at Godwyn. At that moment the complicity between the two men was blatant, and Merthin hoped the rest of the guild could see it. Godwyn said: "Parchment is costly. That drawing was scraped and reused long ago."
Merthin nodded as if he believed Godwyn. There was still no sign of Jeremiah. Merthin might have to win the argument without the help of the original plans. "The stones would have prevented the problem that is now causing the cracks," he said.
Philemon put in: "You would say that, wouldn't you? But why should we believe you? It's just your word against Elfric's."
Merthin realized he would have to stick his neck out. All or nothing, he thought. "I will tell you what the problem is, and prove it to you, in daylight, if you will meet me at the riverside tomorrow at dawn."
Elfric's face showed that he wanted to refuse this challenge, but Bill Watkin said: "Fair enough! We'll be there."
"Bill, can you bring two sensible boys who are good swimmers and divers?"
"Easy."
Elfric had lost control of the meeting, and Godwyn intervened, revealing himself as the puppet master. "What kind of a mockery are you planning?" he said angrily.
But it was too late. The others were curious now. "Let him make his point," said Bill. "If it's a mockery, we'll all know soon enough."
Just then, Jeremiah came in. Merthin was pleased to see that he was carrying a wooden frame with a large sheet of parchment stretched across it. Elfric stared at Jeremiah, shocked.
Godwyn looked pale and said: "Who gave you that?"
"A revealing question," Merthin commented. "The lord prior doesn't ask what the drawing shows, nor where it came from--he seems to know all that already. He just wonders who handed it over."
Bill said: "Never mind all that. Show us the drawing, Jeremiah."
Jeremiah stood in front of the scales and turned the frame around so that everyone could see the drawing. There at the ends of the piers were the piles of stones Merthin had spoken of.
Merthin stood up. "In the morning, I'll explain how they work."
Summer was turning into autumn, and it was chilly on the riverbank at dawn. News had somehow got around that a drama would take place and, as well as the members of the parish guild, there were two or three hundred people waiting to see the clash between Merthin and Elfric. Even Caris was there. This was no longer merely an argument about an engineering problem, Merthin realized. He was the youngster challenging the authority of the old bull, and the herd understood that.
Bill Watkin produced two lads of twelve or thirteen, stripped to their undershorts and shivering. It turned out they were Mark Webber's younger sons, Dennis and Noah. Dennis, the thirteen-year-old, was short and chunky, like his mother. He had red-brown hair the color of leaves in autumn. Noah, the younger by two years, was taller, and would probably grow up to be as big as Mark. Merthin identified with the short redhead. He wondered whether Dennis was embarrassed, as Merthin himself had been at that age, to have a younger brother who was bigger and stronger.
Merthin thought Elfric might object to Mark's sons being the divers, on the grounds that they might have been briefed in advance by their father and told wh
at to say. However, Elfric said nothing. Mark was too transparently honest for anyone to suspect him of such duplicity, and perhaps Elfric realized that--or, more likely, Godwyn realized it.
Merthin told the boys what to do. "Swim out to the central pier, then dive. You'll find the pier is smooth for a long way down. Then there's the foundation, a great lump of stones held together with mortar. When you reach the riverbed, feel underneath the foundation. You probably won't be able to see anything--the water will be too muddy. But hold your breath for as long as you can and investigate thoroughly all around the base. Then come up to the surface and tell us exactly what you find."
They both jumped into the water and swam out. Merthin spoke to the assembled townspeople. "The bed of this river is not rock but mud. The current swirls around the piers of a bridge and scours the mud out from underneath the pillars, leaving a depression filled only with water. This happened to the old wooden bridge. The oak piers were not resting on the riverbed at all, but hanging from the superstructure. That's why the bridge collapsed. To prevent the same thing happening to the new bridge, I specified piles of large rough stones around the feet of the piers. Such piles break up the current so that its action is haphazard and weak. However, the piles were not installed and so the piers have been undermined. They are no longer supporting the bridge, but hanging from it--and that's why there are cracks where the pier joins the arch."
Elfric snorted skeptically, but the other builders looked intrigued. The two boys reached midstream, touched the central pier, took deep breaths, and disappeared.
Merthin said: "When they come back, they will tell us that the pier is not resting on the riverbed, but hanging over a depression, filled with water, large enough for a man to climb into."
He hoped he was right.
Both boys stayed under water for a surprisingly long time. Merthin found himself feeling breathless, as it were, in sympathy with them. At last a wet head of red hair broke the surface, then a brown one. The two boys conversed briefly, nodding, as if establishing that they had both observed the same thing. Then they struck out for the shore.
Merthin was not completely sure of his diagnosis, but he could think of no other explanation for the cracks. And he had felt the need to appear supremely confident. If he now turned out to be wrong, he would look all the more foolish.
The boys reached the bank and waded out of the water, panting. Madge gave them blankets which they pulled around their shaking shoulders. Merthin allowed them a few moments to catch their breath, then said: "Well? What did you find?"
"Nothing," said Dennis, the elder.
"What do you mean, nothing?"
"There's nothing there, at the bottom of the pillar."
Elfric looked triumphant. "Just the mud of the riverbed, you mean."
"No!" said Dennis. "No mud--just water."
Noah put in: "There's a hole you could climb into--easily! That big pillar is just hanging in the water, with nothing under it."
Merthin tried not to look relieved.
Elfric blustered: "There's still no authority for saying a pile of loose stones would have solved the problem." But no one was listening to him. In the eyes of the crowd, Merthin had proved his point. They gathered around him, commenting and questioning. After a few moments, Elfric walked away alone.
Merthin felt a momentary pang of compassion. Then he recalled how, when he was an apprentice, Elfric had hit him across the face with a length of timber; and his pity evaporated into the cold morning air.
56
The following morning, a monk came to see Merthin at the Bell. When he pulled back his hood, Merthin did not at first recognize him. Then he saw that the monk's left arm was cut off at the elbow, and he realized it was Brother Thomas, now in his forties, with a gray beard and deep-set lines around his eyes and mouth. Was his secret still dangerous after all these years? Merthin wondered. Would Thomas's life be in danger, even now, if the truth came out?
But Thomas had not come to talk about that. "You were right about the bridge," he said.
Merthin nodded. There was a sour satisfaction in it. He had been right, but Prior Godwyn had fired him, and in consequence his bridge would never be perfect. "I wanted to explain the importance of the rough stones, back then," he said. "But I knew Elfric and Godwyn would never listen to me. So I told Edmund Wooler, then he died."
"You should have told me."
"I wish I had."
"Come with me to the church," Thomas said. "Since you can read so much from a few cracks, I'd like to show you something, if I may."
He led Merthin to the south transept. Here and in the south aisle of the choir Elfric had rebuilt the arches, following the partial collapse eleven years ago. Merthin saw immediately what Thomas was worrying about: the cracks had reappeared.
"You said they would come back," Thomas said.
"Unless you discovered the root cause of the problem, yes."
"You were right. Elfric was wrong twice."
Merthin felt a spark of excitement. If the tower needed to be rebuilt..."You understand that, but does Godwyn?"
Thomas did not answer the question. "What do you think the root cause might be?"
Merthin concentrated on the immediate problem. He had thought about this, on and off, for years. "This is not the original tower, is it?" he said. "According to Timothy's Book, it has been rebuilt, and made higher."
"About a hundred years ago, yes--when the raw wool business was booming. Do you think they made it too high?"
"It depends on the foundations." The site of the cathedral sloped gently to the south, toward the river, and that might be a factor. He walked through the crossing, under the tower, to the north transept. He stood at the foot of the massive pillar at the northeast corner of the crossing and looked up at the arch that stretched over his head, across the north aisle of the choir, to the wall.
"It's the south aisle I'm worried about," Thomas said, slightly peevishly. "There are no problems here."
Merthin pointed up. "There's a crack on the underside of the arch--the intrados--at the crown," he said. "You get that in a bridge, when the piers are inadequately grounded, and start to splay apart."
"What are you saying--that the tower is moving away from the north transept?"
Merthin went back through the crossing and looked at the matching arch on the south side. "This one is cracked, too, but on the upper side, the extrados, do you see? The wall above it is cracked, too."
"They aren't very big cracks."
"But they tell us what is happening. On the north side, the arch is being stretched; on the south side, it's being pinched. That means the tower is moving south."
Thomas looked up warily. "It seems straight."
"You can't see it with the eye. But if you climb up into the tower, and drop a plumb line from the top of one of the columns of the crossing, just below the springing of the arch, you will see that by the time the line touches the floor it will be adrift of the column to the south by several inches. And, as the tower leans, it's separating from the wall of the choir, which is where the damage shows worst."
"What can be done?"
Merthin wanted to say: You have to commission me to build a new tower. But that would have been premature. "A lot more investigation, before any building," he said, suppressing his excitement. "We have established that the cracks have appeared because the tower is moving--but why is it moving?"
"And how will we learn that?"
"Dig a hole," Merthin said.
In the end Jeremiah dug the hole. Thomas did not want to employ Merthin directly. It was difficult enough as it was, he said, to get the money for the investigation out of Godwyn, who seemed never to have any money to spare. But he could not give the job to Elfric, who would have said there was nothing to investigate. So the compromise was Merthin's old apprentice.
Jeremiah had learned from his master and liked to work fast. On the first day, he lifted the paving stones in the south transept. Next day, his men
started excavating the earth around the huge southeast pier of the crossing.
As the hole got deeper, Jeremiah built a timber hoist for lifting out loads of earth. By the second week he had to build wooden ladders down the sides of the hole so that the laborers could get to the bottom.
Meanwhile, the parish guild gave Merthin the contract for the repair of the bridge. Elfric was against the decision, of course, but he was in no position to claim that he was the best man for the job, and he hardly bothered to argue.
Merthin went to work with speed and energy. He built cofferdams around the two problem piers, drained the dams, and began to fill the holes under the piers with rubble and mortar. Next he would surround the piers with the piles of large rough stones he had envisaged from the start. Finally, he would remove Elfric's ugly iron braces and fill the cracks with mortar. Provided the repaired foundations were sound, the cracks would not reopen.
But the job he really wanted was the rebuilding of the tower.
It would not be easy. He would have to get his design accepted by the priory and the parish guild, currently run by his two worst enemies, Godwyn and Elfric. And Godwyn would have to find the money.
As a first step, Merthin encouraged Mark to put himself forward for election as alderman, to replace Elfric. The alderman was elected once a year, on All Hallows Day, the first of November. In practice, most aldermen were reelected unopposed until they retired or died. However, there was no doubt that a contest was permitted. Indeed, Elfric himself had put his name forward while Edmund Wooler was still in office.
Mark required little prompting. He was itching to put an end to Elfric's rule. Elfric was so close to Godwyn that there was not much point in having a parish guild at all. The town was in effect run by the priory--narrow, conservative, mistrustful of new ideas, careless of the interests of the townspeople.
So the two candidates began drumming up support. Elfric had his followers, mainly people he either employed or bought materials from. However, he had lost face badly in the argument over the bridge, and those who took his side were downcast. Mark's supporters, by contrast, were ebullient.
Merthin visited the cathedral every day and examined the foundations of the mighty column as they were exposed by Jeremiah's digging. The foundations were made of the same stone as the rest of the church, laid in mortared courses, but less carefully trimmed, as they would not be visible. Each course was a little wider than the one above, in a pyramid shape. As the excavation went deeper, he examined every layer for weakness, and found none. But he felt confident that eventually he would.