Dial Africa--that's what the marvelous British saxist Trevor Watts has done, and he's made a clear connection between the rich percussion tradition of West Africa and his own background as a top free-jazz improviser. The word "moire" suggests the layering of two patterns to create a third, and that certainly does describe the makeup of this band: it features Watts, along with two fellow Britishers on bass guitar and trap set, and a quartet of Ghanaian drummers/vocalists. The music uses simple structres and yields elongated performances, with Watts spinning exuberant and earthy solos over the Africans' rhythmic base. At times Watts's soprano rides smoothly over the rhythm; other times he uses the horn to pry open the music's monochromatic tonality; and in one piece on his most recent CD, Live in Latin America (on ARC Music, Watts's own label), the instrument becomes a controlling dervish that seems to have sprung from the rhythm itself. I suppose that a strict jazz purist could object to the harmonic stasis of the music, just as an inflexibie folklorist might complain about those saxophone solos disturbing the hypnotic, chanted pulse. But everyone else has the opportunity to hear the transportive power in this cross-cultural express. Friday, 8:30 and 10:30 PM, Hot House, 1565 N. Milwaukee; 235-2334.