Referring to Fig. 1, let xOy be the plane of rotation of a rigid rod AOA' consisting of a series of pairs of masses symmetrically disposed about O. Thus at a distance r on either side of O are masses mr. Let AOA' rotate with uniform angular velocity Ω, about the axis Oz and let the plane xOy simultaneously rotate about the axis Ox, supposed fixed in space, with constant angular velocity w. Let ρ be the perpendicular distance mrMr of mr to the axis Ox.