aves 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.

Supporting. Giving aid; helping another.

Synchronous. Acting at the same time, and to the same extent.
Thus if two wheels, separated from each other at great distances,
are so arranged that they turn at exactly the same speed, they
are said to turn synchronously.

Tactics. The art of handling troops in the presence of an enemy.
It differs from strategy in the particular that the latter word
is used to explain the movements or arrangement of forces before
they arrive at the battle line.

Tandem. One before the other; one after the other.

Tangent. A line drawn from a circle at an angle, instead of
radially.

Technically. Pertaining to some particular trade, science or art.

Tenuous. Thin, slender, willowy, slight.

Tetrahedral. This has reference to a form which is made up of a
multiplicity of triangularly shaped thin blades, so as to form
numerous cells, and thus make a large number of supporting
surfaces. Used as a kite.

Theories. Views based upon certain consideration.

Theoretical. Where opinions are founded on certain information,
and expressed, not from the standpoint of actual knowledge, but
upon conclusions derived from such examinations.

Torsion. A twist; a circular motion around a body.

Transmitted. Sent out; conveyed from one point to an