A pitot tube is used by aircraft to measure their approximate velocity. Pitots can be heated to set the incoming air to a referenced temperature. The pressure is routed to a sensor, and the velocity is calculated. This information can be used as an input to the flight computer or as a standby in case the more accurate doppler system goes down in military aircraft. Modern pitots closely resemble machine gun barrels in appearance.

I think this definition was a little after Webster 1913's time.

Pi*tot's" tube` (?). Hydraul.

A bent tube used to determine the velocity of running water, by placing the curved end under water, and observing the height to which the fluid rises in the tube; a kind of current meter.

 

© Webster 1913.