Folkie Gordon Bok; 'Crucible'; James Hendricks's bronzed twigs

In an age of electronic blare and blast, a folk song quietly sung to an acoustic guitar comes like a post card from a world apart. That, at least, is the feeling one has after a performance by Gordon Bok, who played to a small audience of aficionados at Jordan Hall last Friday. He was skillfully joined by Cindy Kallett, who sang some songs in her own fine voice but mumbled away her diction - a cardinal flaw in narrative music.

Bok, by contrast, was lucid. Hailing from coastal Maine, he has woven fine music out of sea chantey and narrative ballad. Appearing in sandals, jeans, and an open-necked shirt, he traded not on glitter and drive but on understated affection. Sometimes he sang songs like ''Bound Down to Newfoundland'' or ditties like ''Marblehead Neck,'' accompanied by virtuoso guitar playing. Sometimes he just played, or sang a cappella. G-rated and nonideological, his pieces (many of which he has recorded) seek nothing more than to bestow a sense of calmness, wistfulness, and nostalgia.

It was so calm, in fact, that the concert never had a climax. Never mind. Bok sings like a man sitting atop the hatch on a schooner, and hearing him is like reading a post card addressed to someone else. This is performance not as hype but as intimacy, welcome in a loudening age, and well worth the hearing.