Here it is shown how the percussion made by r upon h moves h, and how such percussion fails and is lost in the wheel.

4 7, 3 1 3 4, 1 2 2 12 2, c p, h r, m f, K n, g

When the weight departs from c and comes to h, it delivers its percussion; and the weight of the whole wheel, in the time of that percussion, remains such as would be needed for the power of that percussion to turn the wheel one sixth of its circle, in such a way that the weight p would find itself perpendicular to the attachment of its axle, that is, in the manner in which the weight K stood when it descended from the place where it was. In the proportion in which the centres of the weights on the right are found with those on the left, in the same proportion are found the centres of the rods on the right with those on the left. A site chosen for the wheel and its weights at which it stops. Now test whether the percussion of h, in falling from c, has the power to turn the 6th of the wheel; if not, it is not valid. And even if it did turn that 6th, it would then make no further motion, since the little attendant g bears upon itself a great weight, which the wheel, having run on by the blow, gives it, and which would want to return to its natural site; and such weight would make it so that in the succeeding percussion of the weight f the wheel could not then turn its 6th part as it did before, because the weight it sustains, as said, g, opposes it. Hence such a wheel is sophistical, as has thus been demonstrated.

If you wish to measure by another, simpler way the powers of the weights on the right of such instruments — what proportion they have with the weights on the left — measure all the spaces from the central line of the wheel to each of the weights on the right, and set them one after another along one and the same line; and do likewise with the weights on the left along that same line; and there you will be able to measure by how much one line exceeds the other. The same excess that is in the power of the right-hand weights over the power of the left-hand weights, such will be exactly that of the two said lines.