History was on stage at Wolf Trap last night in the persons of the Brothers Humphrey of the Preservation Hall Jazz Band. Their grandfather, Jim Humphrey, taught virtually an entire generation of New Orleans musicians, including some of the pioneer jazz players.

Percy Humphrey, on trumpet, led the group through two sets of the standard New Orleans repertoire of stomps, spirituals, and pop songs of yesteryear. His ensemble lead draws from five decades of brass band work and holds up well, and his solos include some growling hand-muted horn.

Carlinetist Willie Humphrey Jr., Who became a professional musician in 1918, excels in low register and has remarkable sustaining powers.

The style and the spirit, perhaps even the shade, of Big Jim Robinson were present as well, incarnate in trombonist Frank Demond, who game fresh expression to the Tailgate approach of his late mentor.

Early in the program, pianist "Sing" Miller sang "I Sing Because I'm Happy," creating a mood that took over for the evening. "Closer Walk" brought out good solo statements by the front line. Percy got off a gruff vocal on "Ice Cream," and banjoist Narvin Kimzall's "Memories" was right out of the '20s. The inevitable encore, "The Saints," had hundreds snake dancing up and down the aisles.

The Preservation Hall Jazz Band performs at Wolf Trap again tonight.