"Some people come out and say, 'That is the dumbest damn thing I've ever seen in my life, a bunch of people shoving rocks down the ice,'" said John Bittner of the Potomac Curling Club.

Then there are the people who stay around to curl, like Chris Chapman, who's been with the club for four years. "I got sucked into it. I came out with my then-boyfriend just to watch. But they didn't let me just watch," she said. "I hated it for the first session. Then it grew on me."

Anyone can curl. You can start curling when you're big enough to handle the stone, usually age 14, and never retire.

You don't have to be a Scot to love curling, but the game owes Scotland for its development. Curling became a major sport there in the 1500s, though its beginnings are obscure.

Curling is a little like shuffleboard or lawn bowling or any game where you can knock your opponent's disk or ball to a lesser position or out of play. In curling, a granite stone weighing 42 1/2 pounds is swung by its handle and smoothly released down the ice like a bowling ball, to a target of concentric circles called the "house." The playing area, or "sheet," is about half the length of a football field and 14 feet wide.

"You get the feeling that it's a muscle sport," said Bittner. "But it's really a matter of coordination. If you do everything right you use the momentum of the stone to provide the lift.

"In fact, when anybody asked to see the game, I used to trot out a girl who weighed 96 pounds who was a super curler."

A vintage 1960s movie the club showed at an open house put it more delicately: "Don't get the idea this is just for men," a voice on the soundtrack said as a picture of a woman curling came on the screen. "She handles the rock as easily as a stream iron."

There is one time when muscle helps, and that's in sweeping. Every curler has a broom; by sweeping the ice smooth and warming it in front of the moving stone, a person's teammates can speed the stone to a good position: guarding another stone, smacking an opponent's stone and sending it spiraling away (that's a "wick and roll"), or landing on the "button," the center ring.

It all depends on the strategy of the "skip," who is the quarterback of the team. He semaphores with arm and broom, signaling the player the way a catcher signals a pitcher, to put a little left English or a little right English on the stone when it's released. That determines which way the stone will curve or "curl," making an "in-turn" or an "out-turn."

"The nomenclature is what drives people crazy," said Bittner.

Ordell Olson, president of the club, who's been curling since 1955, agrees. "This in-turn and out-turn. I have to stop and figure it out every time. Instead of just clockwise and counterclockwise, it's in-turn and out-turn."

To confuse things even more, a "rink" isn't just the ice the game is played on, it's also what you call a team of four curlers.

Unlike bowling, where the boards never change, in curling the ice rarely stays the same: It can warm or cool enough to make a difference even during a single game.

"This is keen ice," said Bittner one recent frosty evening at Cabin John. "It takes very little effort to make the rock travel the distance. Tonight almost everyone is throwing heavy. See the stones drifting through from one end to the other."

Some of the curlers were bundled up in thick hand-knit letter sweaters, with Canadian maple leaves and beavers knitted into the design. Some were wearing tam-o'-shanters bedecked with plaid ribbons, and some had chestfuls of souvenir medals from tournaments they call "bonspiels."

It's not a professional sport in America; according to Bittner, tradition has been that to bet on a game would get you thrown out of a club; to accept more than a trophy, unheard of. It's a matter of honor.

"A guy would rather lose a game than be thought a bad sport," said Bittner. "It almost gets saccharine. When you make a shot you will get as many pats on the back from your opponents as you get from your own people."

Curlers encourage each other with cries of "Good sweeping!" or "Nice rock!"

"Some are polite: You can see underneath they are really mad at you," said Chapman. "But most people are very pleasant, even if you make a mistake.

"I brought a guy out from the office to try it. He said, 'I just want somebody to tell me I screwed up when I screwed up! I don't want this good-sport stuff.' He didn't come back."

In the warming room at the skating rink, the curlers find hot coffee and companionship between games. It's the old curling tradition of "stacking the brooms," when players would leave their brooms on the ice outside and go into the house where they'd kill a pint. Eventually they'd finish the game.

The Potomac curlers don't have a real clubhouse, so they schedule parties and potluck suppers once a month. "The curlers will have a party at the drop of a stone," said club member Neil Bell.

His wife Katie said, "It's a social outing," it's one place they both know other couples, instead of trying to introduce each other to friends from their respective offices.

Despite the companionship and the good sports, curling is competitive. This is one reason the Potomac curlers usually put husbands and wives on different rinks. "They keep marriages together longer by not putting them on the same team," said Neil Bell.

"It's like playing partners in bridge," said Olson. "We prevent a lot of going-home arguments that way, where the husband says to the wife, 'If only you'd thrown this way. . .'"

Katie Bell picked up her first rock last year. "I'm one of the ones they say 'good shot!' and I know damn well it's not a good shot. You don't have to be athletic. When I tell people at work I'm going to throw a 42-pound stone. they look at me and shriek."

Off the ice, the curlers in this club are computer experts, government economists, a doctor, a naval architect, a real-estate man, a dentist, an army captain, a public-relations man, a lawyer, a parasitologist. Several players hail from Canada, where curling is a big national sport.

Despite curling's Scottish heritage, there are only two Scots in the club: Iain and Janet Hay, who've been in it for two years. "When we first got here," said Janet Hay, "they thought, 'Oh! The Scots are here!' But actually we aren't very good.Before we came to this country we only played one season."

Gracie Clifford may be part Scot. Wrapped up in her curling sweater, her white hair peeking out from under her cap, she gets ready to walk down the ice to help sweep. "I found a death certificate that said a great-grandfather might have been Scottish. It would be fun to think I came by this by inheritance," she said. "I was delighted: Oh, boy! Born in Scotland! Now I can wear all this regalia and not be an imposter!"

Jim MacPherson strolled into the warming room and twisted off the top of his broom handle. "Good for snake bite, frost bite, what have you," he said. But the hollow broom handle decorated with Tartan ribbons was empty. "Not for long," he said. A curling gear catalog that was lying around listed it as the "whiskey model curling brush."

Other gear is curling shoes: you can tell a curler if his shoes don't match: one sole is crepe and the other has a Teflon surface for sliding on to follow through when delivering a stone.

In the warming room, Dave Leal wears a wool sock over his slippery-soled shoe; he takes the sock off and drapes it over the wall of the rink when he goes on the ice.

He glides along the ice in a perpetual motion on one foot, slightly kneeling with the other knee. One arm is out and the other holds a broom, but this curious fact doesn't detract from his gracefulness. Eloquent is the word for the motion as he almost floats to the other end of the ice rink. But the man has no ice skates on. He's a curler.

Leal is an expert curler, been throwing big stones down the ice since he was a kid in Canada. Olson says that at bonspiels, before the games begin, Leal goes out and slides all the way from one end of the ice to the other.

"No one else does this," Olson says. "The opposition sees it and they wonder, 'Oh no, what have we got ourselves in for now?'"