ONE:Personally, we know more about Aristotle than about any other Greek philosopher of the classic period; but what we know does not amount to much. It is little more than the skeleton of a life, a bald enumeration of names and dates and places, with a few more or less doubtful anecdotes interspersed. These we shall now relate, together with whatever inferences the facts seem to warrant. Aristotle was born 384 B.C., at Stageira, a Greek colony in Thrace. It is remarkable that every single Greek thinker of note, Socrates and Plato alone281 excepted, came from the confines of Hellenedom and barbarism. It has been conjectured by Auguste Comte, we know not with how much reason, that religious traditions were weaker in the colonies than in the parent states, and thus allowed freer play to independent speculation. Perhaps, also, the accumulation of wealth was more rapid, thus affording greater leisure for thought; while the pettiness of political life liberated a fund of intellectual energy, which in more powerful communities might have been devoted to the service of the State. Left an orphan in early youth, Aristotle was brought up by one Proxenus, to whose son, Nicanor, he afterwards repaid the debt of gratitude. In his eighteenth year he settled at Athens, and attended the school of Plato until the death of that philosopher twenty years afterwards. It is not clear whether the younger thinker was quite conscious of his vast intellectual debt to the elder, and he continually emphasises the points on which they differ; but personally his feeling towards the master was one of deep reverence and affection. In some beautiful lines, still extant, he speaks of an altar of solemn friendship dedicated to one of whom the bad should not speak even in praise; who alone, or who first among mortals, proved by his own life and by his system, that goodness and happiness go hand in hand; and it is generally agreed that the reference can only be to Plato. Again, in his Ethics, Aristotle expresses reluctance to criticise the ideal theory, because it was held by dear friends of his own; adding the memorable declaration, that to a philosopher truth should be dearer still. What opinion Plato formed of his most illustrious pupil is less certain. According to one tradition, he surnamed Aristotle the Nous of his school. It could, indeed, hardly escape so penetrating an observer that the omnivorous appetite for knowledge, which he regarded as most especially characteristic of the philosophic temperament, possessed this young learner to a degree never before paralleled among the sons of men. He may,282 however, have considered that the Stagirites method of acquiring knowledge was unfavourable to its fresh and vivid apprehension. An expression has been preserved which can hardly be other than genuine, so distinguished is it by that delicate mixture of compliment and satire in which Plato particularly excelled. He is said to have called Aristotles house the house of the reader. The author of the Phaedrus, himself a tolerably voluminous writer, was, like Carlyle, not an admirer of literature. Probably it occurred to him that a philosophical student, who had the privilege of listening to his own lectures, might do better than shut himself up with a heap of manuscripts, away from the human inspiration of social intercourse, and the divine inspiration of solitary thought. We moderns have no reason to regret a habit which has made Aristotles writings a storehouse of ancient speculations; but from a scientific, no less than from an artistic point of view, those works are overloaded with criticisms of earlier opinions, some of them quite undeserving of serious discussion.Inherent or cooling strains in castings is much more intricate than shrinkage: it is, in fact, one of the most uncertain and obscure matters that pattern-makers and moulders have to contend with. Inherent strains may weaken castings, or cause them to break while cooling, or sometimes even after they are finished; and in many kinds of works such strains must be carefully guarded against, both in the preparation of designs and the arrangement of patterns, especially for wheels and pulleys with spokes, and for struts or braces with both ends fixed. The main difficulty resulting from cooling strains, however, is that of castings being warped and sprung; this difficulty is continually present in the foundry and machine-shop, and there is perhaps no problem in the whole range of mechanical manipulation of which there exists more diversity of opinion and practice than of means to prevent the springing of castings. This being the case, an apprentice can hardly hope for much information here. There is no doubt of springing and strains in castings being the result of constant causes that might be fully understood if it were not for the ever-changing conditions which exist in casting, both as to the form of pieces, the temperature and quality of metal, mode of cooling, and so on.
