TWO:(1.) Into what classes can gearing be divided?(2.) What determines the wearing capacity of gearing?(3.) What is the advantage gained by employing wooden cogs for gear wheels?(4.) Why are tangent or worm wheels not durable?
TWO:Plato, like Socrates, makes religious instruction the basis of education. But where the master had been content to set old beliefs on a new basis of demonstration, the disciple aimed at nothing less than their complete purification from irrational and immoral ingredients. He lays down two great principles, that God is good, and that He is true.142 Every story which is inconsistent with such a character must be rejected; so also must everything in the poets which redounds to the discredit of the national heroes, together with everything tending in the remotest degree to make vice attractive or virtue repellent. It is evident that Plato, like Xenophanes, repudiated not only the scandalous details of popular mythology, but also the anthropomorphic conceptions which lay at its foundation; although he did not think it advisable to state his unbelief with equal frankness. His own theology was a sort of star-worship, and he proved the divinity of the heavenly bodies by an appeal to the uniformity of their movements.143 He further taught that the world was created by an absolutely good Being; but we cannot be sure that this was more than a popular version of the theory which placed the abstract idea of Good at the summit of the dialectic series. The truth is that there are two distinct types of religion, the one chiefly235 interested in the existence and attributes of God, the other chiefly interested in the destiny of the human soul. The former is best represented by Judaism, the latter by Buddhism. Plato belongs to the psychic rather than to the theistic type. The doctrine of immortality appears again and again in his Dialogues, and one of the most beautiful among them is entirely devoted to proving it. He seems throughout to be conscious that he is arguing in favour of a paradox. Here, at least, there are no appeals to popular prejudice such as figure so largely in similar discussions among ourselves. The belief in immortality had long been stirring; but it had not taken deep root among the Ionian Greeks. We cannot even be sure that it was embraced as a consoling hope by any but the highest minds anywhere in Hellas, or by them for more than a brief period. It would be easy to maintain that this arose from some natural incongeniality to the Greek imagination in thoughts which drew it away from the world of sense and the delights of earthly life. But the explanation breaks down immediately when we attempt to verify it by a wider experience. No modern nation enjoys life so keenly as the French. Yet, quite apart from traditional dogmas, there is no nation that counts so many earnest supporters of the belief in a spiritual existence beyond the grave. And, to take an individual example, it is just the keen relish which Mr. Brownings Cleon has for every sort of enjoyment which makes him shrink back with horror from the thought of annihilation, and grasp at any promise of a happiness to be prolonged through eternity. A closer examination is needed to show us by what causes the current of Greek thought was swayed.As remarked in the case of other machines treated of, there is no use of describing the mechanism of trip-hammers; it is presumed that every engineer apprentice has seen trip-hammers, or can do so; and the plan here is to deal especially with what he cannot see, and would not be likely to learn by casual observation.
