b. Balloons of elongated form have been propelled by an engine placed in the car, driving either a large screw propeller or wings.
c. Various attempts have been made to work flying machines (generally having some form of wings) by the power of a man’s hands and feet, with very little success.
Section 60.—MOTIVE POWER.
It is assumed that all physical energy is derived more or less directly from the sun, whose rays combine: 1, heat; 2, light; 3, actinic or chemical power.
Heat may be obtained:
a.
By direct use of the sun’s rays.
b.
From any combustible material.