Abstract: An apparatus for measuring in situ the viscosity of a fluid in a sealed container which includes a spherical ball forming an integral package before any fluid is placed within the container. The apparatus further includes a composite ball consisting of a spherical core of one material surrounded by one or more layers of different materials distributed spherically about the core. The container may also be supported by an angular support member which angularly positions the container such that the ball will move within the container through the fluid at a specific speed. A sensing device is provided along the wall of the container to measure the speed of the ball wherein the sensing device includes a pair of sensors spaced apart by a known distance to sense when the ball passes by each of the sensors providing a speed which is useful for calculating the viscosity of the fluid.