If John Philip Sousa could have looked through the smoggy skies over the West Lawn of the Capitol Saturday night, he would have smiled with glee. Imagine the National Symphony Orchestra, guest conductor and Sousaphile Keith Brion and an estimated 35,000 music lovers gathered in a circuslike salute to the Washington-born "March King," the second of this summer's "Concerts at the Capitol" by the NSO.

"His music was an American crazy quilt," said WJLA newscaster Renee Poussaint, introducing the audience to the syncopated music Sousa loved. Brion, who left a professorship at Yale University to pursue a career modeled after that of the composer and conductor, bounded on stage in Sousa-period Marine uniform, re-creating for the crowd a concert of historical accuracy, directing in the "abbreviated" Sousa style. Women of the metropolitan Washington chapter of the Ladies Victorian Society of America, also in period dress, introduced each number.

The audience was a crazy quilt, too. Most arrived early for the performance to reserve a vantage point and picnic spot. Children, balloons, fried chicken and picnic blankets decorated the lawn. In the gathering darkness, a man with a pipe, almost a magical silhouette, danced through the crowd.

Later during the concert, two women were seen doing aerobic exercises to the music. And a bearded man conducted the orchestra with his feet for his laughing daughter. U.S. Capitol police officers strolled leisurely through the crowd, occasionally checking for opened wine and beer bottles.

"We've visited all the landmarks, just everything," said Morris Mitchell of Pulaski, Tenn., picnicking with his family. "We just wanted to look and see what this was like."

"I love the concerts on the Mall," said Alice Bucca of District Heights. She and her son Steve sat perched on the Capitol steps facing the band, where the crowd was more silently attentive than on the lawn. "If you come all the way into the city for these concerts, you don't want to listen to everyone's conversation."

As the orchestra played an encore of "Stars and Stripes Forever," the audience clapped and marched in place, and then provided two patriotic encores of its own by spontaneously singing "The Star-Spangled Banner" and "God Bless America."