- Software name: appdown
- Software type: Microsoft Framwork
- size: 51MB
His body was scarred and disfigured, as though many surgical operations had been performed upon it.A distinct parallelism may be traced in the lines of evolution along which we have accompanied our two opposing schools. While the Academicians were coming over to the Stoic theory of cognition, the Stoics themselves were moving in the same general direction, and seeking for an external reality more in consonance with their notions of certainty than the philosophy of their first teachers could supply. For, as originally constituted, Stoicism included a large element of scepticism, which must often have laid its advocates open to the charge of inconsistency from those who accepted the same principle in a more undiluted form. The Heracleitean flux adopted by Zeno as the physical basis of his system, was164 much better suited to a sceptical than to a dogmatic philosophy, as the use to which it was put by Protagoras and Plato sufficiently proved; and this was probably the reason why Bothus and Panaetius partially discarded it in favour of a more stable cosmology. The dialectical studies of the school also tended to suggest more difficulties than they could remove. The comprehensive systematisation of Chrysippus, like that of Plato and Aristotle, had for its object the illustration of each topic from every point of view, and especially from the negative as well as from the positive side. The consequence was that his indefatigable erudition had collected a great number of logical puzzles which he had either neglected or found himself unable to solve. There would, therefore, be a growing inclination to substitute a literary and rhetorical for a logical training: and as we shall presently see, there was an extraneous influence acting in the same direction. Finally, the rigour of Stoic morality had been strained to such a pitch that its professors were driven to admit the complete ideality of virtue. Their sage had never shown himself on earth, at least within the historical period; and the whole world of human interests being, from the rational point of view, either a delusion or a failure, stood in permanent contradiction to their optimistic theory of Nature. The Sceptics were quite aware of this practical approximation to their own views, and sometimes took advantage of it to turn the tables on their opponents with telling effect. Thus, on the occasion of that philosophical embassy with an account of which the present chapter began, when a noble Roman playfully observed to Carneades, You must think that I am not a Praetor as I am not a sage, and that Rome is neither a city nor a state, the great Sceptic replied, turning to his colleague Diogenes, That is what my Stoic friend here would say.262 And Plutarch, in two sharp attacks on the Stoics, written from the Academic point of view, and probably165 compiled from documents of a much earlier period,263 charges them with outraging common sense by their wholesale practical negations, to at least as great an extent as the Sceptics outraged it by their suspense of judgment. How the ethical system of Stoicism was modified so as to meet these criticisms has been related in a former chapter; and we have just seen how Posidonius, by his partial return to the Platonic psychology, with its division between reason and impulse, contributed to a still further change in the same conciliatory sense.
"Louvain,Writers on mechanical subjects, as a rule, have only theoretical knowledge, and consequently seldom deal with workshop processes. Practical engineers who have passed through a successful experience and gained that knowledge which is most difficult for apprentices to acquire, have generally neither inclination nor incentives to write books. The changes in manipulation are so frequent, and the operations so diversified, that practical men have a dread of the criticisms which such changes and the differences of opinion may bring forth; to this may be added, that to become a practical mechanical engineer consumes too great a share of one's life to leave time for other qualifications required in preparing books. For these reasons "manipulation" has been neglected, and for the same reasons must be imperfectly treated here. The purpose is not so much to instruct in shop processes as to point out how they can be best learned, the reader for the most part exercising his own judgment and reasoning powers. It will be attempted to point out how each simple operation is governed by some general principle, and how from such operations, by tracing out the principle which lies at the bottom, it is possible to deduce logical conclusions as to what is right or wrong, expedient or inexpedient. In this way, it is thought, can  be established a closer connection between theory and practice, and a learner be brought to realise that he has only his reasoning powers to rely on; that formul?, rules, tables, and even books, are only aids to this reasoning power, which alone can master and combine the symbol and the substance.
It is generally a safe rule to assume that any custom long and uniformly followed by intelligent people is right; and, in the absence of that experimental knowledge which alone enables one to judge, it is safe to receive such customs, at least for a time, as being correct.
Beginning at the tool there is, first, a clamped joint between the tool and the swing block; second, a movable pivoted joint between the block and shoe piece; third, a clamped joint between the shoe piece and the front saddle; fourth, a moving joint  where the front saddle is gibed to the swing or quadrant plate; fifth, a clamp joint between the quadrant plate and the main saddle; sixth, a moving joint between the main saddle and the cross head; seventh, a clamp joint between the cross head and standards; and eighth, bolted joints between the standards and the main frame; making in all eight distinct joints between the tool and the frame proper, three moving, four clamped, and one bolted joint.
An apprentice at first generally forms an exaggerated estimate of what he has to learn; it presents to his mind not only a great undertaking, but a kind of mystery, which he fears that he may not be able to master. The next stage is when he has made some progress, and begins to underrate the task before him, and imagine that the main difficulties are past, that he has already mastered all the leading principles of mechanics, which is, after all, but a "small matter." In a third stage an apprentice experiences a return of his first impressions as to the difficulties of his undertaking; he begins to see his calling as one that must involve endless detail, comprehending things which can only be studied in connection with personal experience; he sees "the horizon widen as it recedes," that he has hardly begun the task, instead of having completed iteven despairs of its final accomplishment.A proof of this proposition is furnished in the case of standard machine tools for metal-cutting, a class of machinery that for many years past has received the most thorough attention at the hands of our best mechanical engineers.