Abstract: Apparatus for supporting a first structure on a second structure so that relative movement between the two structures is permitted in three mutually perpendicular directions only comprises three flexible shafts connected between the first structure and the second structure and mutually inclined so that their axes of torsional restraint intersect at a position at or relatively close to the center of mass of the first structure and a load carried by the first structure. The apparatus may include damping means connected between the first and second structures to provide a vibration and shock isolating arrangement and lying in a common plane which includes the center of mass of the first structure and a load carried by the first structure.