"If you can't stand good music, you better get out of here quick," Atlanta's Piano Red told the folks jammed inside the Library of Congress' Whittall Pavilion. "I'm going to work on everybody here. I'm Dr. Feelgood and I'm going to make you feel good when you leave here."

Willie Lee Perryman, who earned his doctorate at the behest of Aretha Franklin, then preceeded to rock the staid halls of the library with the pure abandon of barrel-house and boogie-woogie blues piano. Kicking off with the admonition, "Play It Red," he romped through personal chestnuts like "The Right String, Baby. But the Wrong Yo-Yo," "Red Boogie" and "Rockin' With Red," the last two of which were million-sellers in the '50s.

Perryman, 68, was preceded by San Francisco blues harmonica virtuoso J. C. Burris, 53, who reached down into his utility belt for the different blues harps from which he drew effects as disparate as train whistles and lonesome swamps. Burris also played African rhythm bones, cajoled his hand-made wooden dolls into jigs and dances and played his body with his hands in a variation on ancient hand-jive routines. Burris "sent his hands to school" in showing the wide-eyed audience the vaired percussive effects and cross rhythms inherent in each person's body.

Piano Red's older brother was the legendary pianist Speckled Red, and Burris' uncle and teacher was the famed Sonny Terry. One hears in their music the traditions that have been passed down and expanded, but that have never moved away from pure, acoustic invention. Setting a beat with his feet and coaxing hand-clapped accents from the audience, Burris wove earthy harmonica smelodies around one insistent blue piece whose chorus spoke directly to the upbeat heart of the matter. "We keep on holdin' on to this old upset world . . ."

The two performers are here for the National Folk Festival at Wolf Trap through Sunday.