It's a holiday this weekend for the National Symphony Orchestra's strings. With the violins and their cousins of various sizes on vacation, the brass, woodwinds and percussion are enjoying a chance to show how good they are on their own. And under the genial guidance of Frederick Fennell, one of the world's leading exponents of music for wind ensemble, they are showing it brilliantly.

Last night's program was an unalloyed delight. Tonight's--focusing largely on wind serenades and opening with Mozart's superb Serenade in B-flat, K. 361--may turn out to be even better. For two programs back to back (and a Labor Day program tomorrow), rehearsal time must have been short, but there were no signs of it in the performance. There was no sense of deprivation in the absence of strings, no feeling of sameness in a whole evening of wind music. The program's primary impact was one of sheer variety in styles, emotional flavors and sound textures.

The music's vintage ranged from the 1500s to the work of composers still vigorously alive--though it was weighted largely toward the 20th century--a golden age of music for wind ensemble. It began and ended with music for instruments imitating voices: Andrea Gabrieli's "Aria della battaglia" and Kurt Weill's "Kleine Dreigroschenmusik," adapted from the themes of "The Threepenny Opera."

Gabrieli's piece is closely modeled on one of the most striking vocal works of the French Renaissance, Cle'ment Jannequin's "La Bataille," which describes graphically the thundering hoofbeats of cavalry, the clash of blades against armor, stirring fanfares and shouts of victory. Gabrieli's adaptation has a fine baroque paradox when the wind instruments imitate voices that were imitating wind instruments--but the work is a stunning success even in the simplest and most basic terms. Those who know the Janne'quin song find the words running through their minds. Others simply enjoy a stirring predecessor of the "1812" Overture.

The Weill suite, with the familiar vocal numbers transposed to instruments, preserves the brash, jazzy flavor of the original stage work. Such songs as "Mack the Knife," the Tango-Ballad and the rabble-rousing final chorale gain as much as they lose in the transposition, at least when the instruments are in hands as skilled as those of the NSO wind players. Last night's performance was dazzling throughout, particularly in the splendidly rowdy "Cannon Song."

The program also included a beautifully orchestrated and effectively shaped Adagio by Joaqui'n Rodrigo, who is best known for his highly popular guitar concertos. A jaunty, insignificant little march by Beethoven was paired with a paraphrase by Hindemith (from his "Sinfonia Serena"), which finds strange, haunting implications in what seemed a simple piece of music.

Even amid such varied and distinctive programming, there was something very special about the NSO's first performance of the virtuosic, superbly crafted Concerto for 23 Winds by Washington-born Walter Hartley. The composer was present to share the warm and well-earned applause with the conductor and orchestra.