ClipArt ETC
"To find the center of gravity of any irregular plane figure, but of uniform thickness throughout, divide one of the parallel surfaces into triangles, parallelograms, circles, ellipses, etc., according to the shape of the figure; find the area and center of gravity of each part separately, and combine the center of gravity thus found in the same manner." —Hallock 1905

Center of Gravity of an Irregular Plane

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