Even the lure of Saturday's sunshine did not keep a sizable crowd from the final concert for the season of National Musical Arts at the National Academy of Sciences. The free concert was a celebration of melody, pure and simple, through chamber works at Mozart, Loeffler, Barber and Poulenc. And there were no disappointments.

Mozart's Duo for Violin and Viola in B Flat Major did not come through as elegantly as desired, but the rough and romantic approach of Burl Senofsky and Karen. Tuttle did highlight the melodic impulse of the piece. A quick recovery from a duel of pitches in the cantabile was a fascinating intrusion.

Violist Tuttle's tone was also tentative in Loeffler's Two Rhapsodies for Oboe, Viola and Piano, but pianist Patricia Gray and oboist Sara Watkins succeeded in unveiling the lovely melancholy that hides behind the charm of this score. Gray was equally convincing in Barber's turbulent Sonat for Cello and Piano and in the Poulenc Trio for Piano, Oboe and Bassoon.

With Poulence the afternoon ended on a hectic, happy note. The trio was rushed madly, gaining in fabulous momentum what it lost in phrasing. Gray's piano was the perfect straight man for the humor of Watkins' oboe and Truman Harris' bassoon, and there were many smiles at the close.