The night train left the city at ten. Carriage nine was almost empty. The heater under the seats was broken. It blew out cold, dusty air and nothing else.
夜班列车十点驶出了城市。九号车厢里几乎没有人。座位下面的暖气坏了，只吹出冰冷、带着灰尘的风，别的什么也没有。
Imani sat by the window in her big coat. She pulled her scarf up to her nose. She could see her own breath in the air.
伊玛尼穿着厚大衣，坐在窗边，把围巾拉到鼻子上。她能在空气中看见自己呼出的白气。
One other passenger sat at the far end. He was a tall man with a toolbag on his knees. He wore two scarves and a wool hat. He looked as cold as she felt.
另一位乘客坐在车厢的另一头。那是一个高个子男人，膝盖上放着一个工具包。他围着两条围巾，戴着一顶羊毛帽，看上去和她一样冷。
At twenty past ten, a loud bell rang. It was a harsh, shaking sound, like an old school bell. Imani jumped up from her seat. The noise came from her own bag. The bag stood on the floor under her seat.
十点二十分，一阵响亮的铃声响起。那是一种刺耳而震颤的声音，像老式学校的铃。伊玛尼从座位上一跃而起。声音来自她自己的包。那只包放在她座位下面的地板上。
"Sorry!" she called. She pulled out a round brass alarm clock. She bought it that morning at a street market. The seller let her have it for almost nothing.
“对不起！”她喊道。她从包里拿出一只圆形的黄铜闹钟。这是她今天早上在街边市场买的。摊主几乎是白送给她的。
"It's a little loud," the seller said. She thought that was funny then. She did not think so now.
“它有点吵。”摊主当时说。那时她觉得这很好笑。现在可笑不出来了。
She pressed the button on top. The bell stopped. The clock showed twenty past ten. She did not set any alarm. She was sure of that.
她按下顶上的按钮。铃声停了。钟上显示十点二十分。她并没有设过任何闹铃。这一点她很肯定。
The tall man came down the carriage. "May I look?" he asked. "I fix machines at work. My name is Xander."
高个子男人沿着车厢走了过来。“我能看看吗？”他问，“我的工作就是修机器。我叫桑德。”
"Please do," said Imani. "I'm Imani. I only got it today."
“请看吧，”伊玛尼说，“我叫伊玛尼。我今天才买的。”
Xander turned the clock over in his big hands. He looked at the back and the bottom. He touched the small lever at the side. "This is the test lever," he said. "Push it and the bell rings once. The alarm is off. It should be silent."
桑德用他的大手把钟翻过来。他看了看背面和底部，碰了碰侧面的小拨杆。“这是测试拨杆，”他说，“一推，铃就响一声。闹铃是关着的。它应该安安静静才对。”
"But it rang," said Imani.
“可是它响了。”伊玛尼说。
"Yes, it did." He gave the clock back. "Let's see if it does it again."
“是的，响了。”他把钟还给她。“我们看看它会不会再响。”
They sat together on the same bench. It was warmer with two people close. Xander took a pencil and an old ticket from his pocket. He wrote the time on the back. Twenty past ten.
他们一起坐在同一条长椅上。两个人挨在一起暖和一些。桑德从口袋里拿出一支铅笔和一张旧车票，把时间写在背面。十点二十分。
Nothing happened for a long time. The train rattled through dark fields. Lights from far houses flashed by and were gone. Imani put the clock on the floor. She watched it.
很长一段时间什么也没发生。列车哐当哐当地穿过漆黑的田野。远处房屋的灯光一闪而过，消失不见。伊玛尼把钟放在地板上，盯着它。
At twenty to eleven, the bell rang again. Imani almost dropped the clock. Xander laughed and wrote down the time. "Twenty minutes," he said. "It rings every twenty minutes."
十点四十分，铃声又响了。伊玛尼差点把钟掉了。桑德笑了，记下了时间。“二十分钟，”他说，“它每二十分钟响一次。”
"But why?" asked Imani.
“可是为什么呢？”伊玛尼问。
"That is the puzzle," said Xander. "We have eight hours and nowhere to go. Let's solve it."
“这就是谜题，”桑德说，“我们有八个小时，又无处可去。来解开它吧。”
Imani liked that. Her fingers were cold, but her mind woke up. "Clue one," she said. "Every twenty minutes."
伊玛尼喜欢这个主意。她的手指冰冷，头脑却清醒了起来。“线索一，”她说，“每二十分钟一次。”
"Good." Xander wrote it down. "Now we watch for clue two."
“好。”桑德把它写下来。“现在我们留意线索二。”
At eleven, they both sat very still. The train hummed. A door banged far away. Then something knocked under the seat. It was a hard, short knock, like a hand on a drum. A moment later, the bell rang.
十一点，两个人都一动不动地坐着。列车嗡嗡作响。远处有一扇门砰地关上。接着座位底下有什么东西敲了一下。那是又硬又短的一声敲击，像一只手拍在鼓上。过了片刻，铃响了。
"Did you hear that?" whispered Imani. "First a knock. Then the bell."
“你听到了吗？”伊玛尼低声说，“先是敲一下，然后铃响。”
"Clue two," said Xander. He wrote the words "knock first". He looked pleased.
“线索二，”桑德说。他写下了“先敲”两个字，看上去很满意。
Imani looked at the clock on the floor. Xander put his hand under the seat. He waited with his eyes closed. After a few seconds, he smiled.
伊玛尼看着地板上的钟。桑德把手伸到座位底下，闭着眼睛等。几秒钟之后，他笑了。
"Clue three," he said. "Warm air. It comes out of the heater after the bell. It stays for one minute. Then it goes cold again."
“线索三，”他说，“暖风。铃响之后，暖气口会吹出热风，持续一分钟，然后又变冷。”
Imani felt the air with her own hand. It was true. A thin, warm breath touched her fingers and then went away.
伊玛尼用自己的手去感受。确实如此。一缕稀薄的暖气拂过她的指尖，又消失了。
"A knock, a bell, and warm air," she said. "What does it mean?"
“一声敲击，一阵铃声，还有暖风，”她说，“这是什么意思？”
"I don't know yet," said Xander. "But the clock and the heater are friends. I am sure of that."
“我还不知道，”桑德说，“但钟和暖气是一伙的。这我敢肯定。”
He opened his toolbag and took out a small lamp. Then he got down on the dirty floor. He looked under the seat for a long time. Imani held the lamp for him. Her arm began to shake, but she did not mind.
他打开工具包，拿出一盏小灯，然后趴到肮脏的地板上。他朝座位底下看了很久。伊玛尼替他举着灯。她的胳膊开始发抖，可她并不介意。
At last, Xander started to laugh. He laughed so hard that he had to sit on the floor.
终于，桑德笑了起来。他笑得太厉害，只好坐在地板上。
"What is it?" said Imani.
“怎么了？”伊玛尼问。
"Look," he said. He pointed with the lamp. "There is a pipe under your seat. The heater valve is stuck. Every twenty minutes, the pipe jumps and knocks. Your clock stood on the floor, right next to it."
“看，”他说，用灯指了指，“你座位底下有一根管子。暖气阀卡住了。每隔二十分钟，管子就会跳一下，发出敲击声。你的钟就放在地板上，紧挨着它。”
"The knock hit the clock," said Imani slowly.
“敲击撞到了钟。”伊玛尼慢慢地说。
"It hit the little lever. The bell rang. Now watch the next part." He pointed again. "The bell is so loud that it shakes the pipe. The shaking opens the valve a little. The heater coughs out some warm air."
“撞到了那根小拨杆。于是铃响了。再看下一步。”他又指了指。“铃声太响，把管子震动了。震动把阀门打开了一点。暖气就咳出一些热风。”
Imani looked at the clock in her hands. Then she began to laugh too. "So my clock wakes up the heater."
伊玛尼看着手里的钟。然后她也笑了起来。“这么说，是我的钟叫醒了暖气。”
"Yes!" said Xander. "The heater needs a loud noise to start. It is just like me in the morning."
“对！”桑德说，“暖气需要一阵大响动才能启动。就跟我早上一样。”
They laughed until their eyes were wet. The sound ran down the empty carriage. For a moment, it felt like a warm room.
他们笑得眼睛都湿了。笑声沿着空荡荡的车厢传开。有那么一刻，这里感觉像一间暖和的屋子。
Then Xander stood up and took a metal tool from his bag. "Now we do it the quick way," he said. He gave the stuck valve three hard hits. It rang like a bell of its own.
然后桑德站起来，从包里拿出一件金属工具。“现在我们用快办法，”他说。他对着卡住的阀门重重敲了三下。它自己也像铃一样响了起来。
The heater made a long, deep noise. Then warm air poured out under every seat. It smelled a little like burning dust, but it was warm. It was lovely.
暖气发出一声悠长低沉的轰鸣。接着，每个座位底下都涌出了暖风。有点像烧焦灰尘的味道，但它是暖的。真好。
Imani took off her scarf. Xander took off his hat and one of his scarves. They sat back and let the heat reach their feet.
伊玛尼摘下了围巾。桑德摘下了帽子和一条围巾。他们向后靠着，让热气传到脚上。
"Thank you," said Imani. "I think I'll keep the clock. It did a good job tonight."
“谢谢你，”伊玛尼说，“我想我会留着这只钟。它今晚帮了大忙。”
"It did," said Xander. He took the clock from her hands again. He looked at it in the lamp light. His smile slowly changed. "Imani, look at the back."
“确实。”桑德说。他又从她手里接过钟。他在灯光下看着它。他的笑容慢慢变了。“伊玛尼，你看看背面。”
"I looked at it already. It's just brass."
“我已经看过了。只是黄铜。”
"Exactly." He tapped the metal. "There is no door for a battery. There is no hole for a key." He held the clock up to his ear. The hands moved round, smooth and quiet.
“没错。”他敲了敲金属。“这里没有装电池的小门。也没有上发条的孔。”他把钟举到耳边。指针平稳而安静地转动着。
Imani stopped smiling too. The heater roared. The train rushed on into the dark.
伊玛尼也不笑了。暖气轰鸣着。列车冲进了黑暗。
"So," said Xander quietly, "what makes it go?"
“那么，”桑德轻声说，“是什么让它走起来的呢？”
