Metrology apparatus is described that includes a first structure rotatably connected to a second structure by a bearing arrangement. The bearing arrangement includes at least a first friction bearing including parts in sliding contact during rotation of the first structure relative to the second structure. The apparatus includes at least one magnet that relieves the load on the first friction bearing. Multiple magnets, provided in an attracting or repelling arrangement, may be used. The metrology apparatus may include an articulating probe head for a coordinate positioning apparatus.