Georgie Tapps, Georgie Tapps. It's got a rhythm. A sound. Like rain on the roof, like black shoes on hardwood under hot, white lights. A tap dancer named Georgie Tapps? It's almost too good to be true.

It is true.

"My real name is Mortimer Alphonse Becker," says Tapps. "I changed it when I was 7. Not legally. I promised my mother I wouldn't."

He tips, he taps, he laughs. He strides across 11th Street, on the way to the Smithsonian. Still jaunty at 60, he's got his tap shoes tucked under one arm and a cane under the other. The cane was a gift from George M. Cohan. "Oh sure, I knew them all," says Tapps. "All the stars did vaudeville, you know -- Eddie Cantor, Al Jolson Will Rogers . . ."

He danced for Roosevelt, and Queen Elizabeth. He did "Pal Joey" on Broadway, danced with Ruby Keeler, played the Rainbow Room, the music halls, London's Palladium. And this weekend he's a headliner at a large club on Constitution Avenue -- the Smithsonian Museum of American History's festival of American popular entertainment, a weekend-long celebration of things like one-ring circuses, Ferris wheels, county fairs. And last but not least, the dancing stars of vaudeville -- fancy dancer Hal Le Roy doing his "legomania" routine; Charles "Cookie" Cook and Ernest "Brownie" Brown doing knockabout steps; and Georgie Tapps, doing what he does best.

The Smithsonian's got Tapps staying at the Harrington Hotel, a place he finds "depressing," but after more than 50 years on the road he's a genuine trouper, and he doesn't really complain.

He was discovered at 7, dancing the Sailor's Hornpipe at his temple in New York City. Ned Wayburn gave him a three-year dance scholarship, and Tapps left regular school for good. When he returned 10, Wayburn tried to sign him to a 20-year contract. His parents turned it down. "I don't remember what the financial terms were," says Tapps. "I was just a kid. But 20 years is 20 years."

He went on the road, dancing in truck stops, anywhere, and gradually worked his way into vaudeville, doing five 12-minute shows a day, every day. "My first real break came in 1932, the height of the Depression. I danced 'Brother, Can You Spare a Dime' in a satirical review called 'Americana.'" It was an artistic success, but a financial failure.

He was 16 when he played the White House, "too young to be overwhelmed. I think they put me up at the Willard Hotel. I danced Ravel's 'Bolero.'" He was a sensation. The president, confined to a wheelchair, loved the show. The feeling was mutual. "I think he was the most charismatic man I ever met," says Tapps.

And the White House was good for business. His weekly salary jumped from $150 a week to $750, good money for anyone in a time when "you could get asumptuous meal for 75 cents."

Vaudeville died, but Tapps kept tapping . . . at the Roxy and Radio City Music Hall. And at the great hotels, the Rainbow Room, the Latin Quarter, the Persian Room at the Plaza. He did USO shows, nightclubs around the world, even a tour of Africa.

And then, around 1967, it all ended.

"I couldn't believe it at first," says Tapps. "They told me they couldn't book me. The big rooms were closing. No one wanted hoofers anymore." He did nothing for a year and a half, then took a job in a men's clothing store.

"Listen," he says, waiting to rehearse at the Smithsonian, "it pays the bills."

He stayed away from the stage for 10 years and taught dance to keep in shape. In the meantime, shows like "A Chorus Line" and "Sugar Babies" swept the land. Tap dancing was back, and Tapps was ready.

He turns in his seat and spots Hal Le Roy's entrance at the back of the small auditorium. They've known each other since 1929, but haven't seen each other in 15 years. They hug and punch and reminisce.

"Remember, remember?" says Le Roy. "You were dancing and I didn't have a pair of shoes. And you gave me yours!

"Nobody ever danced like this man," he adds exultantly.

Tapps tells him about his show in Los Angeles last year, and gives him a small poster. The show was called "What Ever Happened to Georgie Tapps?"

Now you know.