Chap. XVIII .
An armed Loadstone does not endow an excited piece of Iron with greater vigour than an unarmed .
S uppose there are two pieces of iron, one of * which has been excited by an armed loadstone, the other by one unarmed; and let there be applied to one of them another piece of iron of a weight just proportional to its strength, it is manifest that the remaining one in like manner raises the same and no more. Magnetick versoria also touched by an armed loadstone turn with the same velocity and constancy towards the poles of the earth as those magnetized by the same loadstone unarmed.