This research had, for its object, the investigation of the state of flow in the throats of horizontal Venturi flumes. The investigations showed that for metering purposes, the flow in the horizontal throat cannot be parallel, whatever the form or the proportions of the throat may be. This renders' Incorrect the application, to flumes with a horizontal bed, of the discharge formula, which is based on the assumption that the flow is parallel. Unfortunately, nearly all the Venturi flumes used or built nowadays have horizontal beds and apply this discharge formula. The research was then directed towards finding a solution for this. The result was the development of a new measuring device which has the advantages of the Venturi flume but not its defects, which include the misuse of the discharge formula as mentioned above. In addition,the research led to experiments on the parabolic notch, the discharge formula of which was established mathematically and confirmed by experiments.