Questions of that type often state that your only means of weighing the objects is a balance scale, i.e., you can put balls 1 and 2 on one side and balls 3 and

Questions of that type often state that your only means of weighing the objects is a balance scale, i.e., you can put balls 1 and 2 on one side and balls 3 and 4 on the other to see which pair is heavier, and that's "one weighing". I'm guessing that's what russell's question is, at any rate.