"In a body of equal thickness, as a board, or a slab of marble, but otherwise of an irregular shape,…

"When such a surface is irregular in shape, suspend it at any point, so that it may move freely, and…

"To find the center of gravity of any irregular plane figure, but of uniform thickness throughout, divide…

"In a body free to move, the center of gravity will lie in a vertical plumb-line drawn through the point…

Illustration of an irregular convex decagon. This polygon has some symmetry.

Illustration of an irregular convex decagon. This polygon has some symmetry.

Illustration of an irregular convex decagon. This polygon has some symmetry.

Illustration of an irregular convex decagon. This polygon has some symmetry.

Illustration of an irregular convex decagon. This polygon has some symmetry.

Illustration of an irregular convex dodecagon. This polygon has some symmetry.

Illustration of an irregular convex dodecagon. This polygon has some symmetry.

Illustration of an irregular convex dodecagon. This polygon has some symmetry.

Illustration of an irregular convex heptagon. This polygon has some symmetry.

Illustration of an irregular convex heptagon. This polygon has some symmetry.

Illustration of an irregular convex heptagon. This polygon has some symmetry.

Illustration of an irregular convex heptagon. This polygon has some symmetry.

Illustration of an irregular hexagon. This is also an example of a concave polygon.

Illustration of an irregular hexagon. This is also an example of a concave polygon with symmetry.

Illustration of an irregular hexagon. This is also an example of a concave polygon with symmetry.

Illustration of an irregular hexagon. This is also an example of a concave polygon with symmetry.

"Curves other than arcs of circles are drawn with the pencil or ruling pen by means of curved or irregular-shaped…

Illustration of a nonregular/irregular convcave nonagon. A nonagon is a closed geometric figure with…

Illustration of a nonregular/irregular convcave nonagon. A nonagon is a closed geometric figure with…

Illustration of a nonregular/irregular convcave nonagon. A nonagon is a closed geometric figure with…

Illustration of a nonregular/irregular convex nonagon. A nonagon is a closed geometric figure with 9…

Illustration of a nonregular/irregular convex nonagon. A nonagon is a closed geometric figure with 9…

Illustration of 2 regular congruent nonagons that have the same center. One nonagon has been rotated…

Illustration of an irregular concave octagon. This polygon has some symmetry.

Illustration of an irregular concave octagon. This polygon has some symmetry.

Illustration of an irregular concave octagon. This polygon has some symmetry.

Illustration of an irregular convex octagon. This polygon has some symmetry.

Illustration of an irregular convex octagon. This polygon has some symmetry.

Illustration of an irregular convex octagon. This polygon has some symmetry.

Illustration of an irregular convex octagon. This polygon has some symmetry.

Illustration of an irregular pentagon. This is also an example of a concave polygon with symmetry.

Illustration of an irregular pentagon. This is also an example of a convex polygon with symmetry.

Illustration of an irregular pentagon. This is also an example of a convex polygon with symmetry.

Illustration of an irregular convex polygon with 16 sides that has symmetry. It could be used to show…

"Irregular reflection or diffusion results from the incidence of radiant energy upon an irregular surface,…