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THREE:In working to regular scales, such as one-half, one-eighth, or one-sixteenth size, a good plan is to use a common rule, instead of a graduated scale. There is nothing more convenient for a mechanical draughtsman than to be able to readily resolve dimensions into various scales, and the use of a common rule for fractional scales trains the mind, so that computations come naturally, and after a time almost without effort. A plain T square, with a parallel blade fastened on the side of the head, [80] but not imbedded into it, is the best; in this way set squares can pass over the head of a T square in working at the edges of the drawing. It is strange that a draughting square should ever have been made in any other manner than this, and still more strange, that people will use squares that do not allow the set squares to pass over the heads and come near to the edge of the board.

by Daniel Nyari View on Dribbble

THREE:All these, however, are mere questions of detail. It is on a subject of the profoundest philosophical importance that Aristotle differs most consciously, most radically, and most fatally from his predecessors. They were evolutionists, and he was a stationarist. They were mechanicists, and he was a teleologist. They were uniformitarians, and he was a dualist. It is true that, as we mentioned at the beginning of this chapter, Mr. Edwin Wallace makes him ��recognise the genesis of things by evolution and development,�� but the meaning of this phrase requires to be cleared up. In one sense it is, of course, almost an identical proposition. The genesis of things must be by genesis of some kind or other. The great question is, what things have been evolved, and how have they been evolved? Modern science tells us, that not only have all particular aggregates of matter and motion now existing come into being within a finite period of time, but also that the specific types under which we arrange those aggregates have equally been generated; and that their characteristics, whether structural or functional, can only be understood by tracing out their origin and history. And it further teaches us that the properties of every aggregate result from the properties of its ultimate elements, which, within the limits of our experience, remain absolutely unchanged. Now, Aristotle taught very nearly the contrary of all this. He believed that the cosmos, as we now know it, had existed, and would continue to exist, unchanged through all eternity. The sun, moon, planets, and stars, together with the orbs containing them, are composed of an absolutely ungenerable, incorruptible substance. The earth, a cold, heavy, solid sphere, though liable to superficial changes, has always occupied its present position in the centre of the universe.317 The specific forms of animal life��except a few which are produced spontaneously��have, in like manner, been preserved unaltered through an infinite series of generations. Man shares the common lot. There is no continuous progress of civilisation. Every invention and discovery has been made and lost an infinite number of times. Our philosopher could not, of course, deny that individual living things come into existence and gradually grow to maturity; but he insists that their formation is teleologically determined by the parental type which they are striving to realise. He asks whether we should study a thing by examining how it grows, or by examining its completed form: and Mr. Wallace quotes the question without quoting the answer.203 Aristotle tells us that the genetic method was followed by his predecessors, but that the other method is his. And he goes on to censure Empedocles for saying that many things in the animal body are due simply to mechanical causation; for example, the segmented structure of the backbone, which that philosopher attributes to continued doubling and twisting��the very same explanation, we believe, that would be given of it by a modern evolutionist.204 Finally, Aristotle assumes the only sort of transformation which we deny, and which Democritus equally denied��that is to say, the transformation of the ultimate elements into one another by the oscillation of an indeterminate matter between opposite qualities.

by Daniel Nyari View on Dribbble

THREE:A difficulty which arises in hardening tools is because of the contraction of the steel which takes place in proportion to the change of temperature; and as the time of cooling is in proportion to the thickness or size of a piece, it follows, of course, that there is a great strain and a tendency to break the thinner parts before the thicker parts have time to cool; this strain may take place either from cooling one side first, or more rapidly than another.In the streets and in the caf��s I saw a great many marines who had taken part in the fights near Antwerp and were sent to Brussels for a few days' rest. It was remarkable that so many of them who had only lately looked death in the face, thought that they could not amuse themselves better than by mixing with girls of the worst description. Although I cannot, of course, always believe what soldiers, fresh back from a fight, assert in their over-excited condition, I assumed that I might conclude that things went badly with the defence of Antwerp.

by Daniel Nyari View on Dribbble