Abstract: An improved method and apparatus for measuring fluid flow and controlling fluid flow systems. The invention uses a magnetically responsive float normally resting in contact with a stop element positioned in the flow conduit, with magnetic means positioned upstream. The requisite increase of magnetic force to pull said float element from the stop element against the direction of fluid flow is related to the flow rate, thus serving to indicate same for metering or control purposes. Normally, the current to an electromagnet required to overcome the force of fluid flow is used as a measure of flow rate. This system can also be employed to determine fluid viscosity.