The combination of the Haydn 83rd Symphony ("La Poule," or "the hen") with the Schubert Fifth on a single program seemed a beguiling thought. And beguiling was what it proved to be at the American Chamber Orchestra's concert at Anderson House Saturday afternoon.

The little pickup orchestra, which is dotted with National Symphony players, is not the most polished--but once the players got into the music, under William Yarborough's often imaginative direction, there was a grace that made you forget some of the technical shortcomings.

Not many people have written anything more graceful than the caressing, endearing Schubert Fifth. It is the sound of Mozart, without being as emotionally shattering. There is little premonition of the convulsive forces that would come later with Schubert in the "Unfinished" and the Ninth.

On Saturday the Fifth began to take on its real allure about halfway through the American Chamber Orchestra's performance of the lyrically impassioned second movement. Schubert's wonderful blends of winds and strings very much began to sing. And in the next movement the luftpausen that Yarborough inserted in the minuet seemed a fine idea, even if they were not perfectly realized.

The Haydn was not quite so good, but the work's mordant chromatic punctuations carried the day.

Also, the National Symphony's first violist, Richard Parnas, played a Handel viola concerto in B minor. It had particular gravity in the first two movements and then switched to uninhibited vivacity for the finale. This is a work that Handel wrote for viola and keyboard; it was orchestrated by Henri Casadesus. Parnas was in fine fettle.