Graduated. A marked portion, which is regularly laid off to indicate measurements or quantities.
Gravity. The attraction of mass for mass. The tendency of bodies to move toward the earth.
Gravitatior The force with which all bodies attract each other.
Gyratory. Having a circular and wheeling as well as a rotary motion.
Gyroscope. A wheel, designed to illustrate the laws of motion, which freely revolves in gimbals within a ring, and when set into motion, objects to change its plane of rotation.
Hemispherical. The half of a sphere. The half of an apple would be hemispherical.
Hazardous. That which is doubtful; accompanied by danger.
Helicopter. A type of flying machine which has a large propeller, or more than one, revolubly fixed on vertical shafts, by means of which the machine is launched and projected through the air.
Horizontal. Level, like water.
Hydroplane. A term used to designate an aeroplane which is provided with pontoons, whereby it may alight on the water, and be launched from the surface. The term hydroaeroplane is most generally used to indicate this type of machine.