Cavendish Experiment: Significance of Balls

[MarekS]

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?

 

[Dick]

I believe the reason the small balls are small is because they are connected to a precision torsion balance and it's tough to make such a thing that will support support a few hundred pounds of lead. Simple as that.