Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. EXAMPLES OF TERMS IN COMMON USE AS APPLIED TO MATTER. 31. Before we proceed to a more rigorous treatment of our subject, it may be well to consider what physical truth underlies each of some of the many adjectives in common use as applied to. portions of matter, such as Massive, Heavy, Plastic, Ductile, Viscous, Elastic, Rigid, Opaque, Blue, Coherent, etc. This course secures a twofold gain, so far as the beginner is concerned, for, first, he is thus introduced, in a familiar way, to some of the more important terms which are indispensable in scientific description; and second, he obtains a glance here and there through the whole subject of Natural Philosophy, because the programme before us is so vague as to leave room for innumerable digressions, each introducing some novel but important fact or property. But we must endeavour to be brief, for whole volumes would have to be written before this subject could be nearly exhausted. 32. Every one who has used his senses to any purpose knows, before he comes to the study of our science, a great many of its phenomena, among them some of the yet unexplained. But he knows, as it were, each byitself, and only in its more prominent features; the analysis of the appearances or impressions which he has seen and experienced, and the explanation of the physical fact or process which underlies each of them, are absolutely necessary before he can understand the mode in which they must be grouped, and the reasons for such grouping. 33. Thus he knows that the moon keeps company with the earth, never receding nor approaching by more than a small fraction of the average distance. He also knows that the earth keeps, within narrow limits, at a definite distance from the sun. He has a general notion, at least, that the state...