Sinuous. Wavelike; moving up and down like the waves of the ocean.
Simulates. To pattern or copy after; the making of the like.
Skipper. A thin flat stone.
Spirally-formed. Made like an auger; twisted.
Stability. In airships that quality which holds the ship on an even and unswerving course, and prevents plunging and side motions.
Structural. Belonging to the features of eonstruetion.
Strata. Two or more layers; one over or below the other.
Stream line. In expressing the action of moving air, or an aeroplane transported through air, every part is acted upon by the air. Stream lines are imaginary lines which act upon the planes at all points, and all in the same direction, or angle.
Stupendous. Great; important; above the ordinary.
Substitute. One taken for another; replacing one thing by something else.