Jim Metheny settles himself at his electric Yamaha piano, adjusts the mesh microphone, and begins 6 1/2 hours of what he calls "adult-contemporary-easy listening music," which includes everything from "I Just Called to Say I Love You" by Stevie Wonder to "Cute" by Duke Ellington.

"I know 10,000 songs -- 20,000 songs," he is fond of saying. "And, three of them, I know all the way through." Which is not true. Some, he just prefers not to play. "I've got a deal with Dionne Warwick," he says. "She doesn't do my music, and I don't do hers."

There are piano bars, and there are piano bars. The one Metheny plays in is called Le Pub. It's a refurbished car on the overnight train to Montreal. His job begins every evening at 6:30, as the train moves out of the dim underground glare of Union Station, bound north, to Canada.

Metheny has curly hair, wire glasses and a maroon Amtrak blazer with a lapel pin that reads "Le Pub Entertainer." When not on the train, he lives on a houseboat in the Occoquan River near Woodbridge, with his Great Pyrenees dog, Skipper.

In his spare time, he fishes and putters along the river. He also runs a paddle boat rental business ($6 per hour). He says he used to play backup piano in the "Hee-Haw" band, and for Hank Williams Jr.

"I've played for so many major artists," he sighs, "but, I was just the little worker bee in the background."

His Montrealer audience on weekends consists of skiers heading north, college kids carting laundry bags home, and tired businessmen rummaging through briefcases. But tonight is Thursday. The people who find their way to Le Pub are varied.

The night train sways through the dark countryside. Plastic cocktail glasses jump, coats swing from a wall hook, and Metheny's piano slides out from under him. He leans over and gets it back, without losing a note of "Hey Jude."

John Lyman, a passenger, taps his fingers to the music. He's wearing a flannel shirt, and his feet are propped on a chair. The son of a Hinsburg, Vt., dairy farmer, Lyman is on his way home after a cross-country train trip that took him 20 days.

For him, the train has been a last youthful indulgence before starting a career in accounting-data processing. A hunter and fisherman, he hopes he can find the job he wants in the Green Mountains of Vermont.

Also here are Ellen and Bob Christopher, travel writers from Milford, Conn., and inventors of "The World's Safest Wallet" -- THE ONLY WALLET that can be worn and CONCEALED IN A DOZEN DIFFERENT WAYS. Buy one, and get a free five-language menu translator.

Their wallet has been advertised in Parade magazine, with good results. Its secret is a securing spring clasp, guaranteed not to damage suit jackets, jogging shorts, bathing suits or attache cases. Bob Christopher demonstrates: See, the clip has left no marks on his navy Harve Benard blazer.

Outside, a cold March moon rises, and the cities slip by. Wilmington. Philadelphia. Trenton. Inside, bottles of Inglenook Burgundy and plates of burritos slip by.

Also slipping by are the piano tunes -- jazzy blues while passing a white-lit Empire State Building, and a lot of old hits. Metheny promises some originals, including "Winter Wind" and "A Friendship Song." He rests only long enough for a ginger ale, and a cigarette. His only food craving is for a steak from Ben and Mary's restaurant in Warrenton, Va.

"If you have any favorite songs, just tell old Jim -- the human jukebox," he says.

Metheny's schedule calls for him to do this for 28 straight days. Play to Montreal. Ride back to Washington. Adjust the microphone and the electronic drum machine, and play north to Montreal. What happens after 28 days? "I'm institutionalized," he says. Until when? "Until I promise never, ever to play on the train again."

Playing a rolling, lurching piano is not what most artists would agree to. Metheny always gets his piano back, but he has had close calls. "I've never missed a single note in my life, and if I do, I'll call it 'jazz.' "

There are occasional train power fluctuations, too. Lights flicker and fail. The piano juice stops. The drums go dead. Then, the electricity returns with a slow groan, lights blink back, and Metheny resumes in midstanza. On Thursday, the power surged four times during "Sweet Home Alabama." Said Metheny: "The engineer never did like that song."

As he plays, the train moves farther up the coast, passing Rye and Stamford. "I like it," he says. "You get to play for all age groups. You get to play different styles." There are dinner drinks. After-dinner drinks. After-after-dinner drinks.

The bar car is now assuming the collegiality of a neighborhood watering hole. People call out "Hey ya, Jim -- I liked that." They lean across seat backs to chat. A woman discusses her Norwegian heritage. An older man says he has just eaten his first-ever burrito.

Jim's "Le Pub Entertainer" pin has slipped crookedly by now. The name of a song request is lost, fumbled for and retrieved. "Earth to Captain Jim," he mumbles to himself. "Oh, yes, Barbra Streisand. 'People.' " Then, turning to the microphone: "I've got a request for a beautiful song. This one is number 5,014 on your hit parade. But, it used to be number one."

Trains induce train-talk, and a lot of the conversation revolves around Amtrak, and its cloudy future. Metheny rolls a "Help Save Amtrak" flyer into a tube, puts it to his lips, and sings "Rock-a-bye My Baby With a Dixie Melody" through it. The train lurches forward, and he almost loses the piano.

Earlier in the evening, Metheny had said, in private, "Would you rather have trains that can take you anywhere in America, or another nuclear sub for the generals to play with? That is the stupidest thing." Now, approaching 1 a.m., he repeats it for the Le Pub audience.

"Or, would you rather have pictures of Venus? I mean, every month, you get pictures of the backside of Bo Derek. Why would you want pictures of the backside of a planet? We like trains. We're all train people, and they're trying to take them away from us." Lyman wholeheartedly agrees.

It is very late, and some of the train personnel have come into Le Pub, as the lounge prepares to close. Sitting in the back of the car is Edward Leroy Bright, a gray-haired sleeping car porter who lives in Forestville. He has already told his passengers how to use the fold-down sinks, and about the blue night-lights.

Bright gazes out the Le Pub window, and says he has worked on trains for more than 20 years. He has a train collection in his basement at home, and made Amtrak's last mail run. That was a very sad day. He has photographs of the whole thing, and memories of a television interview. It makes him happy to see people enjoying Le Pub.

Just before Le Pub closes for the night, Metheny says he wants to dedicate a song -- some Duke Ellington -- to the greatest and most dedicated trainman he knows. "This one's for Leroy Bright," he says.

Outside, the train speeds past the snow and maple trees that are winter New England. Bright smiles. He says this train is family. Metheny closes his eyes. The piano stays put, and his hands move like velvet over the keys.