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 .