第14章 What the Low Water Left

The tide went down to minus two point one on the Monday and stayed there for nine hours. Tamar had the array in the water since six thirty and the recorder running into a card the size of her thumb, and she had spent the whole morning on the wall with a thermos and a notebook, watching the flats dry. The charted low water for that day was minus one point three. The predicted astronomical low water was minus one point nine. She had entered minus two point one in the log by nine fifteen, and having entered it she could not stop looking at it. By eleven the Line of Stones was out. By one the Nine Steps were out, all nine of them, black and dripping, going down into the bay in a curve that no engineer would design and no engineer had ever needed to. Past the ninth step the mud came up flat and pale, and out on the flat, forty metres from where she stood, something long and low was lying in the silt. She went down and walked out to it. It was the Ashenholt. Church foundation. Nave walls you could put your arm into, a chancel arch with the stone still keyed across the top of it, and the whole footprint no bigger than a chapel, which was the thing that undid her, because she had expected a church and got a chapel, and a chapel is a building that was never meant to be large. She stood in the nave for a long time with the wind coming across the flat and the water two hundred metres away and coming back. The tithe plate was there. Nine bars, nine steps, a cross at the top, exactly as the ledger drew it, and she had a good camera and a proper job, and she photographed it from six angles and wrote the GPS fix in her notebook with the time and the depth and the fact that the foundation had been exposed, which was a fact the harbourmaster would want in a hurry and the Council would want in a worse hurry. Then she called Ruan. He came out to her in the boat at two, the tide still slack, and he did not get out. He sat in the stern with the outboard up and looked at the foundation for a long time. "You knew," Tamar said. "Everybody knew." "Everybody's stood in it but me." "You weren't here." "I was here." "You weren't here," he said. "There's a difference and it's the whole of the difference, and if you spend the summer here you'll learn it." He put the boat alongside and jumped up onto the wall and crouched at the edge and looked down at the steps. "Your recorder," he said. "What about it?" "What's it sampling?" "Twenty hertz to four hundred. Four elements. Omnidirectional. It's in the water off the ninth step." "It's got a filter on it?" "Ninety hertz high-pass." "That's the whole of your problem," Ruan said. "What?" "You've taken out the only part of it that could ever have mattered." "Why ninety?" "Because you wrote it down in the survey and I read it over your shoulder in the kitchen, which I know is a thing I shouldn't have done." He crouched with his forearms on his knees. "What's under ninety?" "Under ninety is infrasound. Under twenty is basically pressure." "And what lives under ninety?" "Seismic. Traffic. Waves against a wall. Anything mechanical. Anything with a motor in it." "And what doesn't live under ninety?" Ruan did not answer that. He got out a cigarette, looked at it, and put it back in the packet. "There's a church under there," he said. "There's always been a church under there. It isn't a story, it's a hole in the mud with a chapel in it, and I've been in it, and you can go and be in it this afternoon if you've got the boots for it." "You've been in it." "Not this year." "When?" He stood up and looked at the water. "Put your headphones on," he said. "And tell me to keep quiet." She got out the laptop on the wall and put the headphones on and told him to keep quiet. The first six hours were weather, the recorders saying nothing, sea, more weather, a gull that got close enough to make a noise the software flagged and then decided was a gull. The seventh hour was the ebb. The eighth hour was the ebb going out past its own prediction and the low-frequency turning over into itself, which is the sound a bay makes when it is emptying faster than it thinks it is emptying. At the ninth hour the bell arrived. Seven hundred and eighty-two hertz, a fundamental that the kit could barely resolve, with a strike every eleven seconds, and under it a partial at one hundred and fifty-six hertz that had no business being on an antenna in salt water, and the whole of it sat four hertz off the bottom of the analyser's range so that she had to change the window scale to see it at all. She listened to it for six minutes and forty-four seconds. Then it stopped, and the bay came back in, and the record was a flat grey line for the remaining nine hours of the file. Ruan listened to it twice. On the second pass he stopped her, back about forty seconds, and held up a finger. "What," Tamar said. "That's not the water." "It's the tenth step." "It's not the tenth step." "The array is sixty metres off the tenth step." "Tamar," he said. "There's no tenth step." She stopped the playback and looked at him. "There's nine," he said. "There's always been nine. Go and count them in the dark." "And the eleventh second?" "Eleven seconds is the boat." "What boat?" "The boat that stands on the Hard at Bellrigg and knocks itself on the bollard when the tide's making." He took the headphones off her and held them by the band. "Your machine has never heard a boat, because a boat is not a frequency. It's a knock. And your machine hears a knock and calls it a tone, because that's what a tone is." "That's not how a spectrum works." "No," he said. "It's how a church works." She took the headphones back and put them on and sat on the wall with her feet hanging over the sea and looked at the flat for a long time. The tide had turned. The water was coming back up the flat from the west, an inch at a time, and where it reached the tithe plate the plate went under first and the rest of it went under eleven seconds later. "Eleven seconds," she said. "That's right," Ruan said. "That's the boat at Bellrigg and that's the eleventh step, and in about four hundred years the mud will have taken both of them and somebody will come along with a recorder and get a very clean number out of it." She went back to the cottage with the array still in the water and the recorder still running and she sat on the kitchen floor with the laptop on her knees and she did not type anything for an hour. When she typed it was four lines in the observation column of her log, and she wrote them as facts and gave each one a number. Observation nine. Six point four minutes of tone at seven hundred and eighty-two hertz, fundamental, starting twelve forty-one, from a position with no acoustic coupling to any known structure. Observation ten. Strike interval eleven seconds. Observation eleven. Cannot be accounted for by mooring noise, hull noise, thermal noise or instrument self-noise, the first three excluded by the accelerometer and the fourth by the reference channel. Observation twelve. I do not know what it is. Underneath that she wrote a fifth line and left it in. Observation thirteen. Ruan says there is no tenth step. ---