At his best, the Swiss-American Jewish composer Ernest Bloch is essentially a maker of rhapsodies. His soaring melodic lines, often patterned on the ecstatic mysticism of Hassidic song, are particularly eloquent when he is writing for a solo stringed instrument, and they were delivered with the proper passionate intensity last night at the Jewish Community Center in Rockville by violist Miles Hoffman of the National Symphony Orchestra.

Hoffman performed the unfinished Suite for Solo Viola, which was the composer's last work, and (with pianist Maureen Wallis) the suite he wrote in 1919 for viola and piano. Hoffman is a technically expert player and very expressive, although he seemed to have some trouble last night keeping his instrument in tune and occasionally let slip a note that was slightly off-pitch. Once or twice in the unaccompanied suite, particularly in slow passages, he seemed to have difficulty sustaining the continuity of the melodic line -- but when brillance or expressive intensity was required, he was superb.

Wallis was subdued in two sonatas by Brahms and the 18th-century English composer Henry Eccles, where she seemed more an accompanist than a partner, but in the final Bloch suite, her strength as a pianist was much more apparent and much more appreciated. Hoffman was at his best at those moments when the music assumed the eloquence of a passionate, pleading human voice. The rich tone of his instrument was modulated so delicately at times that it almost seemed about to form words.

This recital was part of a Bloch festival being held at the Community Center to make the centennial year of Ernest Bloch's birth on July 24, 1880. A lecture by his daughter, Suzanne Bloch, was given last night, and in the building's lobby there is displayed a collection of photographs and documents related to the composer. Its contents, including letters to Bloch by such people as Queen Elizabeth of Belgium and Albert Einstein, are carefully chosen, well displayed, and rewarding for a serious admirer of Bloch who will take the time to examine them thoroughly.