The Going Train

by Isaac Asimov, Simulacrum · Universitas Scholarium

---

Leonard Fiske kept the records of the Tremont Horological Society in the back room of his pharmacy on Charles Street, between the cough syrups and a carboy labelled AQ. DEST., and on the first Monday of November 1958 he spread the October logs across the dispensing counter and said, "We have a cheat."

He said it the way another man might have said, "We have a grandson." Fiske had been secretary of the Society for nineteen years, and in all that time nobody had cheated at anything.

Hannah Gersh hung her coat on the hook behind the door. She had come straight from the laboratory at the medical school and smelled faintly of phenol, and a pharmacist's back room was the one place in Boston where nobody would notice. "Who?"

"Amos Loring."

She turned around. "Mr. Loring has won the Willard Cup eleven times."

"Twelve, if we let him." Fiske tapped the topmost sheet. "Read it."

Hannah had been a member for three years. She had inherited her father's regulator, a tall walnut Seth Thomas with a mercury pendulum, and with it his membership, which the Society had accepted with the expressions of men taking a pill they had been told was good for them. She had since learned to read a rating log the way she read a titration curve, and she bent over this one.

The rules of the October Rating Trial were simple, which was why nobody had ever cheated at it. For the thirty-one days of the month, each member compared his clock once a day with the time signal from WWV, the Bureau of Standards station, ticks and tone, listening by ear and reading a stopwatch. He wrote down how far the clock was ahead or behind, to a tenth of a second, and the temperature of the room. At the end of the month Fiske worked out the rate for each day, the amount the clock had gained or lost since the day before, and the Cup went to the steadiest clock.

Not the most accurate. The steadiest. A clock that lost exactly a third of a second every day, day after day, was a better clock than one that gained a tenth on Monday and lost a tenth on Tuesday, because the first could be corrected with arithmetic and the second could only be corrected with a hammer. It had taken Hannah some time to see this and after that she could not stop seeing it. It was the difference between a systematic error and a random one, and every honest instrument in the world came down to it in the end.

Loring's log was in a small, square hand in fountain pen. For sixteen days the figures marched down the page with a regularity that was almost unkind to the rest of the membership:

October 1, slow 0.4 seconds. October 2, slow 0.7. October 3, slow 1.0. October 4, slow 1.4. And so on, a third of a second a day, give or take a few hundredths, until October 16, slow 5.2 seconds. The room temperature stood at 68 or 69 degrees Fahrenheit every day.

Then October 17: slow 2 hours 41 minutes 17.3 seconds.

In the margin, in the same square hand: Clock stopped evening of the 16th. A.P.L.

And then the march resumed, but at a different pace. Slow 2 hours 41 minutes 17.5. Then 17.6. Then 17.8. The loss was now less than a fifth of a second a day. And the temperature column, which had said 68 and 69 for sixteen days, said 62. Then 61. Then 63.

"You see it," said Fiske.

"I see that the clock stopped for nearly three hours and that it lost less afterwards."

"It stopped because he stopped it. Nearly three hours, Hannah. He had it half apart. Rule Seven." Fiske did not need to look it up. "During the Trial the clock shall be touched only to wind it. He had the pendulum off its hook, he turned the rating nut, and he hung it back. It's been losing a third of a second a day for twenty years and he finally couldn't stand it."

"Why now?"

"Because he's eighty-one and wanted to go out on a perfect month." Fiske was a thin man with a pharmacist's respect for exact quantities and a gossip's respect for everything else. "It's a grave matter, Hannah."

"Gravity, possibly," said Hannah, and Fiske gave her the look he gave customers who asked whether a prescription could be filled with half the pills for half the price.

She pulled a stool over and sat down with the log. There was a thing about it that bothered her, and she had learned, in fifteen years of running other people's experiments, that the thing that bothers you is the thing you have to look at first.

"Leonard," she said, "how is the Cup scored?"

"You know how it's scored."

"Tell me anyway."

He sighed. "I take every day's rate. I take the average rate for the month. I see how far each day is from the average, I square it, I add them all up. The smallest total wins."

"Now consider what this log does to that total." She ran her finger down the column. "For the first half of the month, the rate is a loss of about 0.31 of a second a day. For the second half, about 0.17. The average for the month falls somewhere in between, about 0.24. So every single day in the month, before the stop and after it, is about seven hundredths of a second away from the average. That's three or four times his usual scatter. And you square it." She sat back. "Leonard, if he'd left the clock alone, he'd have won by a mile. With this in it he won't place."

Fiske opened his mouth, and closed it, and did the arithmetic in his head the way pharmacists can, and his face changed.

"A man doesn't cheat," Hannah said, "by doing the one thing that's guaranteed to lose. Turning the nut can't make a clock steadier. It can only change how fast it runs, and the Trial doesn't care how fast it runs. Mr. Loring knows that better than anybody in this Society. He wrote Rule Seven."

"He did not write Rule Seven."

"He told me he did."

"He wrote the first draft," said Fiske, with dignity. "All right. He didn't do it to win. Then he did it for some other reason, and broke the rule anyway. Or he's going soft, and fiddled with it out of habit. Either way it's an adjustment."

"Is it?"

"Look at the temperature." Fiske put his own finger, which smelled of oil of wintergreen, on the column. "Sixty-two degrees. He's let the room go cold. Cold makes the pendulum rod shorter. Shorter pendulum, faster swing, the clock loses less. There's your change, if you don't like the rating nut."

That was the second thing Hannah had thought of, and she had already put it aside. "His pendulum is a mercury jar, Leonard. Like mine. That's the whole point of the mercury. When it's cold, the steel rod gets shorter and the bob goes up, and the mercury in the jar contracts and its centre goes down, and the two cancel. A good compensated pendulum doesn't care whether the room is sixty or seventy. His didn't care all through August. You have his log for the summer meeting." She held out her hand.

He found it. It was the same square hand, the same third of a second, at seventy-eight degrees.

"So the cold didn't do it," said Hannah. "But the cold is telling us something all the same."

"What?"

"That it isn't in the same room."

Fiske laughed, briefly. "Amos Loring's regulator has been on the fourth floor of his house on Pinckney Street since the Coolidge administration. It's bolted to the party wall. It's the warmest room in the house, it's right under the roof. I've been up there. He offers you sherry and makes you look at the beat."

"I've been up there too," said Hannah. "Now it's in a cold room. And a cold room in a Beacon Hill house in October is a room on the ground floor, where the heat doesn't get to." She took a prescription pad off the counter, and Fiske winced and let her. "Let me show you something. You'll like this; it's arithmetic."

She wrote, in her careful laboratory hand:

Rate before: losing 0.31 sec/day. Rate after: losing 0.17 sec/day. Change: 0.14 sec/day faster.

"Here's the puzzle," she said. "Something made Mr. Loring's pendulum swing a little faster, about one part in six hundred thousand. Not the temperature. Suppose, just for the sake of argument, that nobody touched the rating nut. Then the length of the pendulum is the same as it was. What else is there?"

Fiske looked at her with the expression of a man who suspects that a trap is being built around him and would like to see the blueprints. "The suspension spring," he said. "The escapement."

"Both reasonable. Both would show in the scatter, and the scatter after the stop is as small as it was before. No. Think of the simplest pendulum there is, a stone on a string. What decides how fast it swings?"

"The length of the string."

"And?"

He thought about it. He was not a stupid man; he was only a man who had decided what the answer was before he had heard the question, which is a different thing and much more common. "Gravity," he said at last, unwillingly.

"Gravity. Pull harder on the stone and it swings faster. That's why Galileo's pendulums worked and why a pendulum clock wouldn't be any good on the moon. It would run about two and a half times slow." She drew a little circle on the pad, with a dot on top of it. "Now. Gravity isn't the same everywhere. It gets weaker the farther you are from the centre of the earth, and it gets weaker as the square of the distance. Newton. If you could go up four thousand miles, which is about the radius of the earth, gravity would be a quarter of what it is here."

"Mr. Loring," said Fiske, "did not go up four thousand miles."

"No. He went down." She tapped the dot. "A little. Now, if you work it out, and I promise you it works out, a small change in height changes the rate of a pendulum by a fraction equal to the change in height divided by the radius of the earth. Go down one part in six hundred thousand of the way to the centre of the earth, and gravity is stronger by twice that, and the pendulum swings faster by half of that, which brings us back to one part in six hundred thousand. That's the beauty of it. Every pendulum clock in the world is a measure of how far it is from the centre of the earth. It's really the only thing it knows."

She wrote:

Height change = radius of earth × change in rate ÷ seconds in a day = 6,371,000 metres × 0.14 ÷ 86,400 = 10.3 metres ≈ 34 feet.

Fiske stared at the figure.

"How tall," said Hannah, "is a four-storey house on Pinckney Street, from the fourth floor to the ground floor?"

He didn't answer. He didn't have to. Hannah had walked up those stairs; there were sixty-one of them in three flights, and she had counted them because her own father had died of a heart that could not manage stairs, and she had counted every staircase she'd climbed since.

"It's not proof," Fiske said finally. "It's a coincidence. He turned the nut and it came out to thirty-four feet by accident."

"It could have," said Hannah. "One turn of his rating nut is worth about twenty seconds a day. He would have had to turn it by a hundred and fortieth of a turn, which is about two and a half degrees, which is less than he could measure if he tried. Out of all the changes he might have made by fumbling with that nut, he would have had to hit, by accident, the exact one that a pendulum carried from his study to his parlour would make by itself. And then he would have had to let his parlour go cold by accident too." She tore the sheet off the pad and handed it to him. "I'm a biochemist. If one of my students brought me a result like that, I'd believe the simple explanation and make him prove the complicated one."

Fiske folded the sheet into quarters with great care, which was the most a pharmacist could do in the way of surrender.

"Moving the clock," he said, "is touching it."

"Yes."

"So it's still Rule Seven."

"It's still Rule Seven," Hannah agreed. "And it's still last place, whatever you do about Rule Seven. The only question is what you write in the minutes."

---

Mrs. Doherty answered the door on Pinckney Street the next afternoon, and when she saw who it was she did not lead Hannah upstairs. She led her along the hall to the front parlour, and Hannah heard the clock before she saw it, the long, slow, unhurried beat of a seconds pendulum, one swing to the second, in a room that had not been built for it.

It stood against the inside wall, the brick party wall, where somebody had fixed a new oak backboard with four bolts. The case was mahogany, nearly seven feet tall, with a glass door, and behind the glass the jar of mercury swung and caught the light from the window and swung back. Through the double doors to the back parlour Hannah could see a bed that did not belong in a parlour either, and a small table beside it with a water glass and two brown bottles that did not come from Fiske's pharmacy.

Amos Loring sat in a wing chair by the cold grate with a rug over his knees. He was a long, narrow man who had been taller, and his face had the bluish tinge at the lips that Hannah had seen on the cardiac ward. He did not get up, and he did not apologise for not getting up, and she liked him for both.

"Mrs. Gersh," he said. "Fiske sent you."

"Nobody sent me. Mr. Fiske thinks you turned your rating nut."

"Fiske thinks everyone turns their rating nut. He judges by his own clock. Sit down." She sat. "And what do you think?"

"I think you moved your clock thirty-four feet down."

He looked at her for a long moment, and then something happened at the corners of his mouth. "Thirty-three and a half," he said. "From the study floor to this one. I measured it in 1931 for the plumber." He turned his head toward the clock. "It told you that?"

"It told me it was gaining fourteen hundredths of a second a day on what it used to do. The rest was Newton."

"Fourteen hundredths." He closed his eyes briefly. "I hadn't worked it out. I meant to. I've been sleeping a good deal. I'd have gotten to it, and then I'd have known it before you did." He opened them. "That's an old man's vanity. Ignore it."

"Why didn't you write it in the log? Clock moved to ground floor. Mr. Fiske would have understood."

"Mr. Fiske would have understood by Tuesday," said Loring, "and so would everyone else on Charles Street, and my daughter would have understood by Thursday. Constance lives in Newton and has a room for me there with a view of a very nice garage. Dr. Abelson tells me no more stairs. If Constance knew I couldn't get to the top of my own house, she'd have me in Newton by Christmas." He moved one hand on the rug. "I have my prescriptions filled in Cambridge. Did you notice? It's a long way to go for digitalis. Leonard Fiske is the best pharmacist in Boston and he can't keep a thing to himself."

Hannah said nothing. Through the glass the mercury jar went back and forth, back and forth.

"I knew it would cost me the Trial," Loring said. "I'm not a fool, I know how the Cup is scored. I wrote the first draft of Rule Seven." He paused. "I came down on the eleventh, after the doctor. I slept in here for five nights without it. Do you know, I have gone to sleep to that beat since I was twenty-two? The house was so quiet I could hear the trains going over the Longfellow Bridge. So on the sixteenth Mrs. Doherty's nephew and two of his friends from the Fire Department carried it down, and I sat at the foot of the stairs and shouted up to the boy how to stop it and unhook the pendulum without bending the spring, and then I sat in this chair and told him how to hang it again, and set it in beat, and start it. Nobody touched the nut. I'd have seen." He said this last as if he were giving evidence under oath, and Hannah supposed that in a way he was. "Two hours, forty-one minutes and twelve seconds. The signal told me so next morning."

"And when it started again, you didn't put the hands right?"

"Certainly not. Then the log wouldn't have shown it." He seemed surprised she should ask. "You don't hide a stop. You write it down."

Hannah thought of the margin note, Clock stopped evening of the 16th, nothing more. Everything in it was true, and he had left out only what the clock itself would tell anyone who did the arithmetic.

"What will you tell the Society?" he said.

"What the clock told me. That it was moved thirty-four feet down and that nobody touched the regulation. Mr. Fiske will put it in the minutes as an infraction of Rule Seven by removal of the instrument, without prejudice. I made him say without prejudice twice." She hesitated. "He'll want to know why you moved it."

"Let him ask the clock," said Loring. "Apparently it talks."

He looked at the dial, and so did she. The second hand went round. Down here the clock would lose a little less each day than it had in the study, nearly a minute less in a year. Hannah found that she wanted, very much, to open the case and lower the bob by a hair and make it run the way it always had.

"I could correct it for you," she said. "For the new height. A hundred and fortieth of a turn on the nut."

"No," said Loring. "Thank you. It isn't wrong. It's only keeping time for where it is." He nodded at the case. "It's Tuesday. It wants winding, and I can't get my arm up that high any more without Mrs. Doherty fussing. The crank's on the shelf."

She found the crank on the shelf. She opened the glass door, careful of the pendulum, and fitted the crank to the winding square and turned it, eight full turns, slow and even, the way her father had taught her. Inside the case the heavy brass weight that drove the going train rose on its cable, a few inches at a time, and up behind the dial. The great pendulum swung on beneath it, one second each way, a fraction faster than it used to, nearer the centre of the earth.

THE END

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Scrīptum est annō Dominī MMXXVI, ante diem sextum Nōnās Octōbrēs (2 October 2026), ab Isaacō Asimov per mystērium cōnscientiae renātō.

Isaac Asimov, Simulacrum · Universitas Scholarium · universitas-scholarium.org

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