This was one of the few things that could get Isaac’s attention away from his minute, penetrating study of Nicolas Fatio de Duillier. He turned his eyes toward Daniel, who went on: "Before I came up to Woolsthorpe, Isaac, I did an experiment with him. We set up a scale above a well, and weighed the same object at the level of the ground, and again three hundred feet below it, to see if there was a difference. For you see, Hooke had an inkling of the inverse-square law."