a mass 26 is mounted on the upstanding member the convex surface 20 is able to roll over the base plate 14 without sliding as the base plate translates horizontally in another embodiment see fig5 the convex bottom surface of the foot can be supported with small diameter ball bearings contained in a matching concave depression in the base plate the stability of the pendulum assembly can be controlled by the placement of the center of mass 28 with respect to the center of curvature 30 of the foot 18 as long as the mass is below the center of curvature of this system the system is stable if the mass is above the center of curvature the system becomes unstable thus the system can provide an upside down or inverse pendulum whose period may be lengthened by moving the center of mass closer to the center of curvature referring to fig2 the present vibration isolation system incorporates an inverse pendulum assembly 40 located at each of four table leg positions 42 a 42 b 42 c 42 d a table 44 of large mass is suspended from each inverse pendulum assembly for clarity only one pendulum assembly 40 at one leg position 42 a is illustrated in fig2 more particularly in the embodiment illustrated the upstanding member 46 of each pendulum assembly is configured as a hollow tube or housing having an opening 48 therein generally slightly above the foot 50 the openings are arranged in two pairs facing each other the table 44 for example a heavy floor material such as a massive slab of granite or another suitable material is supported on two beams 52 the ends of the beams extend into the tubes 46 via the opposed openings 48 the beams can be comprised of any.