We may thank Professor Michelson not only for what he has established, but also for what he has unsettled. In his various researches, which I have hastily sketched, but which require diagrams or models to be clearly understood, he has displayed high intelligence, great experimental skill and ingenuity, and unflagging perseverance. With a full appreciation of his work, the Rumford Committee recommended, and the Academy voted, that the Rumford Premium be awarded to him.