provide the best absorption of energy from the oscillating system and provide the desired amount of damping for the specific intended use the boom and the damper are then tested to check the damping characteristics and if they are not right the fluid has to be drained and new fluid with different viscosity inserted for a re test this process is repeated until the desired damping characteristics of the system are obtained such a procedure is quite costly and time consuming and adds considerable cost to the damper another difficulty with the fig1 damper is a result of mass 10 sliding in chamber 22 because too much friction may be involved for optimum damping effectiveness conventional linear bearings may be used to reduce the friction and in some cases may be sufficient however even using conventional linear bearings between mass 10 and the interior of cylinder 12 there may be too much friction because of contact between the balls these problems are overcome with the improvements of fig2 in fig2 a damper 108 which may also be attached to a boom as in fig1 but not shown in fig2 for simplicity is shown comprising a moveable mass 110 slideably mounted in a cylindrical container 112 having a first cylindrical end piece 114 fastened to the right end of cylinder 112 by conventional means not shown a spring 116 has a first end fastened in a recess 118 of mass 110 and a second end fastened to.