I read an article about the Cavendish experiment in Wikipedia: http://en.wikipedia.org/wiki/Cavendish_experiment and I feel I understood all relevant aspects. However, what is the significance of having a pair of big and small balls? Having 4 big balls would create more force (F) thus creating more deflection in the wire and making the experiment more precise by having a bigger angle to measure. Am I mistaken? Is one pair of balls small because they have less inertia to start moving?