Pitot tubeIn 1732, Henri Pitot read a paper to the Royal Academy of Sciences in Paris about an instrument he had invented to measure the flow velocity at different depths of water in the River Seine*. It had a scale and two open vertical glass tubes on a wood frame. The lower end of one pointed down, the other bent at 90º facing the flow. The belief of the time was that flow velocity at a given depth was proportional to the mass above it, meaning increasing velocity at greater depth. Recording the difference in liquid levels in the two tubes, he showed the opposite was true. Henri Darcy improved the design, with the support of Henri Bazin. Today, the Pitot tube has an important application in aerodynamics for the measurement of the airspeed of aircraft.«[Image: Book illustration showing a variation on Pitot tube by another practitioner presented by Fanning,1877.] |
