of its existence 47 The want of polar compression no proof to the contrary 48 Want of proper study gives rise to extravagant conceptions, jumping at conclusions, and formation of "curious theories" 48 CHAPTER III. Remarks on some of the principal cosmogonies. Ancient notions 49 The Nebular hypothesis of Laplace. Early opinions on it. Received into favour. Again condemned as erroneous 50 Defects attributed to it as fatal. New cosmogonies advanced 51 Dr. Croll's collision, or impact, theory discussed 53 Dr. Braun's cosmogony examined 59 M. Faye's "Origine du Monde" defined 61 Shown to be without proper foundation, confused, and in some parts contradictory 65 Reference to other hypotheses not noticed. All more or less only variations on the nebular hypothesis 70 Necessity for more particular examination into it 71 CHAPTER IV. Preliminaries to analysis of the Nebular hypothesis 72 Definition of the hypothesis 73 Elements of solar system. Tables of dimensions and masses 75 Explanation of tables and density of Saturn 78 Volume, density and mass of Saturn's rings, general remarks about them, and satellites to be made from them 79 Future of Saturn's rings 79 Notions about Saturn's satellites and their masses 80 Nature of rings seemingly not well understood 81 Masses given to the satellites of Uranus and Neptune. Explanations of 81 Volumes of the members of the solar system at density of water 82 CHAPTER V.