In his installation piece here, Paul Ludick achieves a very tenuous balance between solemn concern for serious environmental subjects and a sense of humor with which to guide and stimulate consciousness. O Zone, 1989, is an arrangement of 31 identical chairs placed casually through the front area of the gallery. On the back of each chair the name of a city is painted in black; different typefaces suggest regional differences. Places as far-reaching as Uppsala, Tokyo, Missoula, and Thetford are represented in Ludick’s idiosyncratic cartography. On each circular seat, a selection of ten pounds’