Aerodynamics

the science which treats of the force exerted by air when in motion, Aeronautics, the art of aerial navigation by ballooning and aviation. Ballooning involves the use of a baglike receptacle which is made in various shapes, of silk or other material, rendered impervious by a coating of rubber, linseed oil or suitable varnish, and inflated with hydrogen, coal-gas, or other gaseous matter, specifically lighter than air. Aviation discards anything in the shape of a balloon and utilizes aeroplanes or lifting and sustaining surfaces, with apparatus heavier than air. IMG:pg-049.jpg:illustration, p. 49