How is he occupied? Great part of his room is filled with the framework of machinery, the object of which is to make massive globes of metal alternately approach and recede from a light pendulous body, hanging from the roof by a slight silken fibre. This he is carefully watching, and is diligently noting its vibrations through a small telescope from another corner of the room. Can you guess what he is about? These are the scales with which he is weighing the mass of "this great globe which we inherit," and which this apparatus will enable him to ascertain with greater accuracy than you could arrive at, if you were to undertake to determine the weight of this building in which we are now assembled.
"Not let me go to the most recent and most admirable triumph of mathematical skill. Look on this young student in Paris! He is unprovided with any telescope, or any mechanical apparatus but the pen in his hand. Many volumes, however, lie open before him, in which he finds recorded the differences between the observed and computed places of the planets; and, carefully transcribing these, he appears buried in the most intricate calculations. What result has he obtained that makes his cheek flush with truimph! Let me attempt shortly to explain it to you. He has just completed an examination of the irregularities of the most distant planet then known to belong to our system. This remote body, be it observed by the way, was itself discovered to be a planet only some sixty or seventy years ago; and, since it is so distant from the sun that its year is about as long as 84 of our's, it has not yet completed one revolution round the sun, since its real nature was discovered by the late Sir William Herschel. Yet, already, the path in which it ought to move according to the then state of our knowledge was so well known, by the application of the same general laws on which innumerable previous verifications had led astronomers to place implicit reliance, that its deviations from the course they had by anticipation marked out for it, began to fill them with uneasiness. How are these irregularities to be accounted for?
"It cannot surely be, that, having reached the confines of our solar system, the laws which we acknowledge are faintly and imperfectly followed there, as might be the case in some distant province of a mighty empire? No: the laws which the Great Architect of the Universe has impressed on His creation are not as those of earthly potentates; they are felt and obeyed throughout His works. There must then be some cause of which we have been hitherto ignorant, and of which
