The high whine of the fiddle ripped through a fog of cigarette smoke and frying seafood, and leaping onto the stage, two dozen dancers clacked their heels hard with the beat. For the next four minutes, while Reverend Chip and the Moonbrides picked and planked through a barnyard jig, these bright-eyed suburbanites double-stepped and shuffled as briskly and sharply as a hammer on a two-by-four.

As the lady's T-shirt said, "No Sweat, No Fun."

Last Thursday night, they were in Clog Heaven. Stomping, sliding and circling, about 40 faithful cloggers snapped their toe-taps to the sounds of the flat-pick guitar. From Boonsboro, Md., Alexandria and Kensington, they make a weekly pilgrimage to Silver Spring to Captain White's Oyster Bar and sometime clog palace.

"We get together to clog, and we clog to get together," according to Carin Luke, managing editor of the monthly Daily Clog. ("It's 24-hour clog coverage," explained editor Mike Marlin. "It just comes out once a month.")

"It's real up music," Luke said, "lively and loud. I can be dancing all night, and be exhausted, and when the music comes on, I'm ready to go."

Clogging is a kind of back-to-basics dance, focused on the feet and skimpy on the arm movements. Wearing hard soles, granny boots or even professional tap shoes, cloggers strike the floor between each shuffling jump, often combining a do-si-do or Highland knee fling when performing in the more choreographed groups.

It's percussion for nonmusicians, a way of joining in the music by turning the body into a rhythm instrument. But to a novice, it seems something like Gregory Hines reviving a Bojangles routine while wearing Hans Brinker's wooden shoes.

"You could learn the basic steps in 15 minutes," Luke said. "It's just an up-and-down movement, but the down is more important. And once you've got that down, the rest is all embellishment."

"It's a kind of cadence," suggested Bob Caruthers, a Boonesboro fiddler and "occasional" clogger.

"Old-time music is very repetitive, but it has a really tight groove, and that's what you shoot for -- the musicians and the dancers getting together in the groove."

Adam Hubbell, who teaches beginner's and advanced clogging classes at Glen Echo Park, said there are two schools of clogging, "a folksier, mountain buck-dancing type," using a little more toe-tap, and a style related to square dancing and Western swing.

"Good" clogging style runs counter to most traditional dance forms. "It doesn't have the same values as modern dance or ballet," Hubbell said. "It's based on an up-and-down bounce; you're not admired for how smooth you look."

Even so, Hubbell considers himself something of a purist: "A lot of cloggers who start out very good tend to deteriorate -- they develop little mannerisms, or think that getting better means getting louder and faster. I try to show them how the steps can get more complicated, more intricate."

The Thursday night clogging session at Captain White's is an offshoot of what used to be a regular get-together at Rena's restaurant on Twinbrook Parkway, which closed several years ago. Luke said 30 to 50 cloggers and two or three bands show up each week to watch organized groups perform, mix it up in the freestyle moments and even, during the breaks, receive elementary instruction.

It's not for the faint-hearted or frail-eared. Between the heavy heels and the amplified music, clog night at Captain White's can be a deafening experience. But that's part of the fun.

"It just strikes some kind of familiar chord," said Hallie Hallinan of Takoma Park, who began clogging two years ago at Glen Echo. "My grandfather played the Irish fiddle, and he used to play for the grandchildren. We loved it -- but when he played, our parents used to leave the house!"