Before he played a single note, James Galaway had the National Symphony's audience in his pocket last night. When it was time for the Mozart D Major Flute Concerto, Galway came onstage, his gold flute over his shoulder. When he reached the center of the stage, he shook hands with the two first-chair violinists, then bowed to the audience. The formalities over, he turned and pointed his flute straight at the oboe, asking for the official "A".

Then, as Max Rudolf led the orchestra in the opening of the concerto, Galway waited calmly, his left hand in his trouser pocket, the right hand holding the flute up over the right shoulder until it was time to play.

He then entered into one of the beautiful ensemble partnerships of this season as he and Rudolf, turning toward each other, made marvelous sounds and shapes out of Mozart's designs. For proper emphasis, Galway provided an ideal, perky attack; for the smooth melodic lines, a tone as golden as the flute. Surely the brilliant dazzler of a cadenza at the end of the first movement was his own creation, and a marvel. For the slow movement he found the gift of weaving incantatory spells.

After intermission, the great Irishman came back with the Pastoral Concerto he commissioned from Spain's Joaquin Rodrigo. Here were echoes of Falla's "Puppet Show," both in the delicate scoring of solo winds and the spiky turns of melodic and harmonic thought. Here, too, was some fast, intricate, spectacular writing for solo flute and orchestra.

If the musical content is fragile, the atmosphere of the concerto is fragrant. In Galway's and Rudolf's hands, with some eloquent assistance from the orchestra's solo wind players, it was a fascinating affair. It was the first performance of the concerto in the United States.

Rudolf preceded the concerto with a properly sytled and spirited account -- the orchestra's first -- of Mozart's Symphony No. 28, in which the conductor's minimal display produced maximum results. If the violins could spend more time playing Mozart with this man, they could be a fine Mozart ensemble. Mendelssohn's D Minor Symphony, the "Reformation," closed the evening with splendid manner and sumptuous sound.