pitot linkage: aircaft that use actual airspeed indicator dials often depend upon a device called a "pitot tube," named for the person who invented the device, that is usually attached to the outside of the fuselage, or on one wing. In teh purely-mechanical types that prevailed up through the twenties and on into the early forties, airspeed is measured via a tiny airscrew inside the tube, that sends its revolutions through a mechaniical linkage (usually a spinning cable, but knuckle-hinged driveshaft-style linkages also were used) to the relevant dial or dial cluster in the cockpit of the aircraft.
More than you ever wanted to know, I realize, but I have to spout my AFJROTC larnin' someplace (I'm surprised I can still remember all of that stuff!)...
Someone told me a while back that aircraft these days derive airspeed readings from GPS signals, but I find that a bit hard to swallow. Maybe I'm just being old again, but I'd think that would be kind of unreliable in an atmospheric disturbance or something similar.
