Feature article on the Kneisel Hall Chamber Music Festival, which is held annually in Blue Hill and marks its 100th anniversary this year. Kneisel Hall accepts about 50 gifted young musicians each year. The faculty, whose own twice-weekly concerts are always sold out, is the chief attraction for the students, all pre-professionals ranging in age from mid-teens to early thirties. Franz Kneisel, an Austrian violinist often referred to as the father of American chamber music, began bringing gifted music students to train in Blue Hill in 1902. The summer school languished after his death in 1926. But in 1953 it was reestablished by former students Joseph and Lillian Fuchs, pianist Arthur Balsam, and Kneisel\u27s daughter Marianne, and it...