The Boys Book of Model Aeroplanes How to Build and Fly, Them - With the Story of the Evolution of the Flying Machine #264879

It was now found that a very little tilt ing of the planes upward or downward would serve to right the machine when it leaned over The secret, like so many others, was gained by watching the flights of birds. You have perhaps seen a great albatross or sea gull soar without the slightest effort and apparently without motion. Look more closely and you will see that the tips of the broad wings move slightly from time to time, while the main body of the wings remains rigid, which is the great secret of stability in flight.