The magic of the midway, combined with the sunshine of spring, delighted thousands of young and old yesterday as the Smithsonian opened a three-day celebration of the American carnival of years gone by.

Under nearly cloudless skies on the Mall, the Ferris wheel spun to the sounds of children shrieking, while a giant 427-pipe self-playing band organ piped the familiar tunes of the carnival midway.

The Smithsonian's annual spring festival is a salute to a somewhat overlooked American cultural phenomenon--the outdoor amusement business that began roughly 150 years ago with agricultural fairs, which slowly evolved into moneymaking entertainment: the "gaudy shows" that turned into the traveling carnival business. With the 1893 World's Fair in Chicago--at which engineer George W. Ferris unveiled his 2,160-seat spinning wheel--the exotic shows and attractions grew into the amusement parks of today.

This slice of Americana, combining games of skill and chance with old carnival standbys like popcorn, candy apples, and snow cones, fills several exhibit spaces inside the National Museum of American History and spills out to the surrounding lawns.

Everything, except food and drink, is free.

"I like the animals. And I like the snakes--the ones that don't bite," said Wilbert Yarbrough, 5, who was treated to a picnic lunch, a Metro ride, and a day of excitement with 20 kindergarten classmates from Houston Elementary in Northeast. Teacher Fay Miley shepherded the youngsters through a yellow-and-white tent where a 4-H fair provided pigs, rabbits and displays about pig anatomy and rabbit diseases.

Lamont Linkins, 8, from Gale Bailey Elementary in Charles County, confessed that he was "a-scared of the Ferris wheel" and instead stood slurping a snow cone, watching older children who were wielding a heavy wooden mallet, trying to ring a bell atop the 20-foot Hi-Striker that has been a carnival fixture for decades.

Inside the museum, John Bradshaw, 36, of Cumberland County, Va., gave a demonstration of the art of the carnival pitchman. The booming voice and nonstop mouth drew a large crowd as Bradshaw promised to turn a roll of dollar bills into 10s. Once he had attracted the crowd however, he started a rapid-fire sales pitch for knives, pens, and magic tricks--and finally confessed that the dollar trick was a put-on.

"The hardest thing of learning to pitch is getting people to stop and listen," he said later.

The festival, which also includes fortunetellers, ringtossing, films and demonstrations, continues today and Sunday from noon to 5 p.m. in and around the museum at 14th Street and Constitution Avenue NW.