If you stood outside a Riverwest bar and heard The Tritonics playing, you might be lulled into a wind and grind with your date right out there on the sidewalk, so languid, so flowing is the quartet's brand of Jamaican rock steady. Go inside and you might be surprised to see four veteran Milwaukee musicians recreating the slow, soulful bridge that linked ska to reggae in Jamaica in the latter part of the 1960s.