This work, as already explained, is to be devoted to mechanical engineering, and in view of the difference of opinion that exists as to what mechanical engineering comprehends, and the different sense in which the term is applied, it will be proper to explain what is meant by it here.
Presuming the reader to remember what was said of steam hammers in another place, and to be familiar with the uses and general construction of such hammers, let it be supposed steam-hammers, with the ordinary automatic valve action, those that give an elastic or steam-cushioned blow, are well known. Suppose further that by analysing the blows given by hammers of this kind, it is demonstrated that dead blows, such as are given when a hammer comes to a full stop in striking, are more effectual in certain kinds of work, and that steam-hammers would be improved by operating on this dead-stroke principle.
ONE:Having obtained his categories, Aristotle proceeds to mark off the first from the other nine. The subject or substance named in answer to the question, What is it? can exist without having any quality, size, and so forth predicated of it; but they cannot exist without it. Logically, they cannot be defined without telling what they are; really they cannot be conceived without something not themselves in343 which they inhere. They are like the tail of a kite, giving greater conspicuousness and buoyancy to the body, but entirely dependent on it for support. What our philosopher fails to perceive is, that the dependence is reciprocal, that substance can no more be conceived without attributes than attributes without substance; or rather that substance, like all other categories, can be resolved into Relation.241Near Lanaeken I met suddenly a Belgian soldier, who did not trouble me after I had shown him my papers. I was quite astonished to find that man there all by himself, whilst so many Germans were only a few miles away. When I asked whether he knew this, he answered:
ONE:As a result of the foregoing criticism, Aristotle distinguishes four different causes or principles by which all things are determined to be what they areMatter, Form, Agent, and Purpose.226 If, for example, we take a saw, the matter is steel; the form, a toothed blade; the agent or cause of its assuming that shape, a smith; the purpose, to divide wood or stone. When we have enumerated these four principles, we have told everything that can be known about a saw. But Aristotle could not keep the last three separate; he gradually extended the definition of form until it absorbed, or became identified with, agent and purpose.227 It was what we should call the idea of function that facilitated the transition. If the very essence or nature of a saw implies use, activity, movement, how can we define it without telling its purpose? The toothed blade is only intelligible as a cutting, dividing instrument. Again, how came the saw into being? What shaped the steel into that particular form? We have said that it was the smith. But surely that is too vague. The smith is a man, and may be able to exercise other trades as well. Suppose him to be a musician, did he make the saw in that capacity? No; and here comes in a distinction which plays an immense part in Aristotles metaphysics, whence it has passed into our every-day speech. He does not make the saw qua musician but qua smith. He can, however, in the exercise of his trade as smith make many other toolsknives, axes, and so forth. Nevertheless, had he only learned to make saws it would be enough. Therefore, he does not make335 the saw qua axe-maker, he makes it qua saw-maker. Nor, again, does he make it with his whole mind and body, but only with just those thoughts and movements required to give the steel that particular shape. Now, what are these thoughts but the idea of a saw present in his mind and passing through his eyes and hands, till it fixes itself on the steel? The immaterial form of a saw creates the real saw which we use. Let us apply the preceding analogies to a natural object; for example, a man. What is the Form, the definition of a man? Not a being possessing a certain outward shape, for then a marble statue would be a man, which it is not; nor yet a certain assemblage of organs, for then a corpse would be a man, which, according to Aristotle, criticising Democritus, it is not; but a living, feeling, and reasoning being, the end of whose existence is to fulfil all the functions involved in this definition. So, also, the creative cause of a man is another man, who directly impresses the human form on the material supplied by the female organism. In the same way, every definite individual aggregate becomes what it is through the agency of another individual representing the same type in its perfect manifestation.228But on looking at the matter a little more closely, we shall find that Plotinus only set in a clearer light what had all along been the leading motive of his predecessors. We have already observed that Platos whole mythological machinery is only a fanciful way of expressing that independent experience which the mind derives from the study of its own spontaneous activity. And the process of generalisation described in the Symposium is really limited to moral phenomena. Platos standpoint is less individualistic than that of Plotinus in so far as it involves a continual reference to the beliefs, experiences, and wants of other men; but it is equally subjective, in the sense of interpreting all Nature by the analogies of human life. There are even occasions when his spiritualism goes the length of inculcating complete withdrawal from the world of common life into an ideal sphere, when he seems to identify evil with matter, when he reduces all virtue to contempt for the interests of the body, in language which his Alexandrian successor could adopt without any modification of its obvious meaning.434
TWO:That same afternoon also I made the acquaintance of the editor of a local weekly, De Bilsenaar, which was not allowed to appear during the occupation of the place by the Germans. He and others had a great many things to tell me."Covered all over with orange blotches, eh?" asked Prout.
TWO:"I require that everywhere a strict investigation shall take place into the conduct of the soldiers with regard to the life and property of the civilian population.
Before entering on the chain of reasoning which led Aristotle to postulate the existence of a personal First Cause, we must explain the difference between his scientific standpoint, and that which is now accepted by all educated minds. To him the eternity not only of Matter, but also of what he called Form,that is to say, the collection of attributes giving definiteness to natural aggregates, more especially those known as organic specieswas an axiomatic certainty. Every type, capable of self-propagation, that could exist at all, had existed, and would continue to exist for ever. For this, no explanation beyond the generative power of Nature was required. But when he had to account for the machinery by which the perpetual alternation of birth and death below, and the changeless revolutions of the celestial spheres above the moon were preserved, difficulties arose. He had reduced every other change to transport through space; and with regard to this his conceptions were entirely mistaken. He believed that moving matter tended to stop unless it was sustained by some external force; and whatever their advantages over him in other respects, we cannot say that the Atomists were in a position to correct him here: for their349 theory, that every particle of matter gravitated downward through infinite space, was quite incompatible with the latest astronomical discoveries. Aristotle triumphantly showed that the tendency of heavy bodies was not to move indefinitely downwards in parallel lines, but to move in converging lines to the centre of the earth, which he, in common with most Greek astronomers, supposed to be also the centre of the universe; and seeing light bodies move up, he credited them with an equal and opposite tendency to the circumference of the universe, which, like Parmenides and Plato, he believed to be of finite extent. Thus each kind of matter has its appropriate place, motion to which ends in rest, while motion away from it, being constrained, cannot last. Accordingly, the constant periodicity of terrestrial phenomena necessitates as constant a transformation of dry and wet, and of hot and cold bodies into one another. This is explained with perfect accuracy by the diurnal and annual revolutions of the sun. Here, however, we are introduced to a new kind of motion, which, instead of being rectilinear and finite, is circular and eternal. To account for it, Aristotle assumes a fifth element entirely different in character from the four terrestrial elements. Unlike them, it is absolutely simple, and has a correspondingly simple mode of motion, which, as our philosopher erroneously supposes, can be no other than circular rotation.I pitied him from the bottom of my heart, and tried to console him by remarking that it was all a misunderstanding, and that I would see to it that he would soon be released.To direct the attention of learners to certain rules that will guide them in forming opinions in this matter of machine combination, I will present the following propositions, and afterwards consider them more in detail:Aside from the cost or difficulty of obtaining ground sufficient to carry out plans for engineering establishments, the diversity of their arrangement met with, even in those of modern construction, is no doubt owing to a want of reasoning from general premises. There is always a strong tendency to accommodate local conditions, and not unfrequently the details of shop manipulation are quite overlooked, or are not understood by those who arrange buildings.The means of supporting cores must be devised, or at least understood, by pattern-makers; these supports consist of 'prints' and 'anchors.' Prints are extensions of the cores, which project through the casting and extend into the sides of the mould, to be held by the sand or by the flask. The prints of cores have duplicates on the patterns, called core prints, which are, or should be, of a different colour from the patterns, so as to distinguish one from the other. The amount of surface required to support cores is dependent upon their weight, or rather upon their cubic contents, because the weight of a core is but a trifling matter [96] compared to its floating force when surrounded by melted metal. An apprentice in studying devices for supporting cores must remember that the main force required is to hold them down, and not to bear their weight. The floating force of a core is as the difference between its weight and that of a solid of metal of the same sizea matter moulders often forget to consider. It is often impossible, from the nature of castings, to have prints large enough to support the cores, and it is then effected by anchors, pieces of iron that stand like braces between the cores and the flasks or pieces of iron imbedded in the sand to receive the strain of the anchors.This work, as already explained, is to be devoted to mechanical engineering, and in view of the difference of opinion that exists as to what mechanical engineering comprehends, and the different sense in which the term is applied, it will be proper to explain what is meant by it here.
