Note:  Do not rely on this information. It is very old.

Radiusof Gyration

Radius of Gyration of a body with respect to an axis is the distance from the axis at which the whole mass of the body should be placed in order that its moment of inertia about that axis should remain the same.

“See a flame in a spark, a tree in a seed; see great things in little beginnings; look not so much to the beginning, as to the perfection, and so we shall be in some degree joyful, and thankful unto Christ.”
–Richard Sibbes, The Bruised Reed and Smoking Flax