"Ah!" said the Rudder, looking wise, "it's in a case like that when I become the Elevator and the Elevator becomes me."
"That's absurd nonsense," said the Blackboard, "due to looseness of thought and expression."
"Well," replied the Rudder, "when the Aeroplane is in position A and I am used, then I depress or elevate the nose of the machine; and, if the Elevator is used, then it turns the Aeroplane to right or left, which is normally my function. Surely our rôles have changed one with the other, and I'm then the Elevator and the Elevator is me!"
Said Lateral Stability to the Rudder, "That's altogether the wrong way of looking at it, though I admit"—and this rather sarcastically—"that the way you put it sounds rather fine when you are talking of your experiences in the air to those 'interested in aviation' but knowing little about it; but it won't go down here! You are a Controlling Surface designed to turn the Aeroplane about a certain axis of the machine, and the Elevator is a Controlling Surface designed to turn the Aeroplane about another axis. Those are your respective jobs, and you can't possibly change them about. Such talk only leads to confusion, and I hope we shall hear no more of it."
"Thanks," said Efficiency to Lateral Stability. "And now, please, will you explain your duties?"