Bluegrass, blue skies and a dozen blue-chip musicians came together in splendid concert yesterdasy afternoon at Wolf Trap. "I've never seen so many people, good Lord," exclaimed guitarist Norman Blake, looking out at the checkered sea of quilts covering the lawn.

Blake, along with his wife Nancy, on cello, and fiddler James Brown, opened Wolf Trap's "Bluegrass Blockbuster." They came as close to duplicating the texture, serenity and virtuosity associated with chamber music as anything you're likely to find in the country idiom.

Autoharpist Bryan Bowers followed suit, lending a baroque air to "Blackberry Blossom." His grunting "pig songs" and his take of what lies under the Scotsman's kilt guaranteed him an encore.

By the time Doc Watson and Bill Monroe and his Blue Grass Boys appeared, encores were a foregone conclusion. Monroe's rising tenor still sounds fine on "Mulesdinner Blues," and his mandolin breaks were consistently crisp and assertive.

A renowned flat picker, Watson showed he's no slouch when it come to finger-picking Mississippi John Hurt's "Pallet on Your Floor." "Mildcow Boogie," featuring one of Watson's two accompanist -- guitarist Cliff Miller -- gave further evidence of his kinship with the blues. A joyously syncopated, tempo-shifting "Sweet Georgia Brown" and a lively rockabilly medley were typical of his eclectic and throughly entertaining performance.