What is "theorem of pappus"

Centrobaric \Cen`tro*bar"ic\, a. [Gr. (?) ? a treatise of Archimedes on finding the center of gravity, fr. ? gravitating toward the center; ? center + ? weight.] Relating to the center of gravity, or to the process of finding it.

Centrobaric method (Math.), a process invented for the purpose of measuring the area or the volume generated by the rotation of a line or surface about a fixed axis, depending upon the principle that every figure formed by the revolution of a line or surface about such an axis has for measure the product of the line or surface by the length of the path of its center of gravity; -- sometimes called theorem of Pappus, also, incorrectly, Guldinus's properties. See Barycentric calculus, under Calculus.