Abstract: The instrument disclosed herein is designed for measuring flow rates and densities of moving fluid streams, including liquids, gases, slurries, and fluids which contain solid materials. Basic components of this instrument are a dynamic leg and a static leg, and flexible connections in each leg which allow for displacement caused by the force of the moving fluid. Each leg is defined by a conduit member having several bends therein, which are joined by straight sections. The legs are held in physical contact along one of the straight sections, and a displacement transducer unit is installed at this point. In operation, part of the incoming fluid to be measured for flow rate fills the static leg and remains in this leg. After the static leg is full, all of the incoming fluid moves through the dynamic leg, and fluid pressure is in equilibrium within the system.