With spiraling phrases of joyful hallelujahs J. Reilly Lewis and his Washington Bach Consort Wednesday night came to the rescue of the 16th Annual Bach Festival taking place this week at the Church of the Ascension and St. Agnes. When illness forced the cancellation a few days ago of the scheduled Abbey Chamber Singers, the consort, which launched the festival Sunday night with the B minor mass, agreed to return for this midweek appearance.

Possibly buoyed by thoughts of their upcoming overseas tour -- the performers leave for Germany next week -- the ensemble produced an evening of spirited music-making. Alternating motets of expressively shifting harmonies with parts I and II of the lively solo Cantata 51, "Jauchzet Gott," Lewis propelled his group firmly along. After an enthusiastic opening prelude and fugue from organist William Neil, the chorus got off to a somewhat ragged start in the first motet, "Der Geist hilft," but rapidly pulled itself together for some finely shaped phrases. The clarity of the choral sound produced a satisfyingly light, transparent texture despite the occasional intrusion of raw lines and jagged rhythms.

Soprano Karen Lynn Ray's pure, open voice imparted a special radiance to the cantata. The fluidity of her exchanges with trumpeter Dennis Edelbrock proved a particular pleasure.

The festival continues with free concerts every night through Sunday at 8.