Richard Bales and the National Gallery Orchestra closed the 38th American Music Festival last night with a remarkable birth -- or perhaps reincarnation is the better word. John Powell's mammoth "Symphony in A" was reborn in a new performance version, prepared over a two-year period by Roy Hanlin Johnson. The size of the achievement, whether measured in terms of Powell's grand concept, Johnson's herculean labor or the orchestra's splendidly sustained interpretation, merited and received a standing ovation form the audience packed into the Eash Garden Court.

Powell, a native of Richmond born in 1882, pursued a major career as a concert pianist until the outbreak of World Was I, when he returned to Richmond to compose and teach. He wrote out of an unfashionable late-19th-century viewpoint, which along with his refusal to join a union contributed to his musical oblivion.

However, as last night's performance indicated, Powell's time may be nigh. If it does indeed come, his editor, Johnson, deserves much credit. Recopying the more than 200 pages of the score, Johnson tightened the hour-long symphony, which has been performed only three times since its completion in 1945, to make it more accessible.

Was it worth the effort? Yes, if one judges not by orginality of language but by sincerity and depth of feeling. Powell speaks the language of a man with strong roots and a full heart. Melding the late Austro-German Romantic style with the folk tradition of his Virginia countryside, he expresses his humanity through a rich melodic outpouring, a lively rhythmic sense and a broad pace, which Johnson aptly describes as "musically ecstatic." Powell's work clearly deserves a recognized place in our musical heritage.

The program also included "Suite in A" by a Powell pupil, Hilton Rufty, who echoed the true feeling and strong craftsmanship of his teacher.