The Halloween ghosts got into the Hall of Musical Instruments at the Smithsonian last night for the concert by the Smithson Quartet. Overall, the performance was tentative, with intonation problems, ensemble difficulties and odd dynamic accents that became mannerisms. In all, it was a good reading, but a shaky performance.

The best playing was in the Haydn G Major Quartet, Op. 77, No. 1. This piece insists on having its own musical way and style and brooks no interference. With the Quartet's full attention on the music, the playing was spirited and almost Romantic.

But for the rest -- the Mozart E-flat Piano Quartet with James Weaver at the fortepiano and the same composer's "Dissonance" Quartet -- the insecurity showed. In the search for authentic performance of older music, the scholar-performer develops doubts. He is, after all, trying to work in a time not his own. Save with great, instinctive artists, scholarship, however factual, remains speculative. We hear tentativeness, playing that is not at home, because it cannot be.

The performers become grim in the quest for authenticity, too much of the museum and not enough of the liveliness of the musical art. It is the letter, not the spirit, and that affected the Mozart performances to everyone's disappointment, including, if signs were to be believed, the quartet's. Fortunately, there is always another concert.