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THREE:To understand Descartes aright, we must provisionally disregard the account given in his work on Method of the process by which he arrived at a new theory of the world; for, in truth, there was nothing new about it except the pro388portion in which fragments taken from older systems were selected and recombined. As we have already noticed, there is no such thing as spinning philosophies out of one’s own head; and, in the case of Descartes, even the belief that he was so doing came to him from Plato; for, along with Aristotle’s dogmatic errors, his sound teaching with regard to the derivation of knowledge had fallen into oblivion. The initial doubt of the Discourse on Method and the Meditations is also Platonic; only it is manifested under an individual and subjective, instead of a universal and objective form. But to find the real starting-point of Descartes’ enquiries we must look for it in his mathematical studies. A geometrician naturally conceives the visible world under the aspect of figured extension; and if he thinks the figures away, nothing will remain but extension as the ultimate material out of which all determinate bodies are shaped. Such was the result reached by Plato in his Timaeus. He identified matter with space, viewing this as the receptacle for his eternal and self-existent Ideas, or rather the plastic medium on which their images are impressed. The simplest spatial elements are triangles; accordingly it is with these that he constructs his solid bodies. The theory of triangular elements was probably suggested by Atomism; it is, in fact, a compromise between the purely mathematical and the materialistic methods. Like all Plato’s fancies, this theory of matter was attacked with such convincing arguments by Aristotle that, so long as his physics remained in the ascendent, it did not find a single supporter; although, as we saw in the last chapter, Plotinus very nearly worked his way back to it from the Peripatetic definition. Even now, at the moment of Aristotle’s fall, it might have failed to attract attention, had not the conditions under which it first arose been almost exactly repeated. Geometrical demonstration had again become the type of all reasoning; there was again a sceptical spirit abroad, forcing men to fall back on the most elementary and universal con389ceptions; an atomistic materialism again threatened to claim at least the whole field of physical enquiry for its own. That Descartes followed the Timaeus in identifying matter with extension cannot be doubted; especially when we see that he adopts Plato’s analysis of body into elementary triangles; but the theory agreed so well with his intellectual predispositions that he may easily have imagined it to be a necessary deduction from his own à priori ideas. Moreover, after the first two steps, he parts company with Plato, and gives himself up, so far as his rejection of a vacuum will permit, to the mechanical physics of Democritus. Much praise has recently been bestowed on his attempt to interpret all physical phenomena in terms of matter and motion, and to deduce them from the unaided operation of natural causes; but this is no more than had been done by the early Greek thinkers, from whom, we may observe, his hypothesis of an initial vortex was also derived. His cosmogony is better than theirs, only in so far as it is adapted to scientific discoveries in astronomy and physiology not made by Descartes himself; for where his conjectures go beyond these they are entirely at fault."I have not ￡20 of ready money in the world."

THREE:It will be seen that what has been singled out as an anticipation of the Darwinian theory was only one application of a very comprehensive method for eliminating design from the universe. But of what is most original and essential in Darwinism, that is, the modifiability of specific forms by the summing up of spontaneous variations in a given direction, the Epicureans had not the slightest suspicion. And wherever they or their master have, in other respects, made some84 approach to the truths of modern science, it may fairly be explained on their own principle as a single lucky guess out of many false guesses.

THREE:Presuming an engineering establishment to consist of one-storey buildings, and the main operations to be conducted on the ground level, the only vertical lifting to be performed will be in the erecting room, where the parts of machines are assembled. This room should be reached in every part by over-head travelling cranes, that cannot only be used in turning, moving, and placing the work, but in loading it upon cars or waggons. One result of the employment of over-head travelling cranes, often overlooked, is a saving of floor-room; in ordinary fitting, from one-third more to twice the number of workmen will find room in an erecting shop if a travelling-crane is employed, the difference being that, in moving pieces they may pass over the top of other pieces instead of requiring long open passages on the floor. So marked is this saving of room effected by over-head cranes, that in England, where they are generally employed, handling is not only less expensive and quicker, but the area of erecting floors is usually one-half as much as in America, where travelling-cranes are not employed.Hetty admitted the fact with a sigh. She had no illusions as to the future. Unless something like a miracle happened Gordon was certain to stand in the dock charged with the murder of a man unknown. Examined in the cold light of day, Gordon Bruce's story was an extraordinary one. Hetty was forced to admit that from the lips of a stranger she would not have believed a word of it.

THREE:(1.) Why cannot the regular working drawings of a machine be employed to construct patterns by?—(2.) What should determine the quality or durability of patterns?—(3.) How can the arrangement of patterns affect certain parts of a casting?—(4.) What means can be employed to avoid inherent strain in castings?—(5.) Why is the top of a casting less sound than the bottom or drag side?—(6.) What are cores employed for?—(7.) What is meant by venting a mould?—(8.) Explain the difference between green and dry sand mouldings.—(9.) Why is sand employed for moulds?—(10.) What generally causes the disarrangement of cores in casting?—(11.) Why are castings often sprung or crooked?—(12.) What should determine the amount of draught given to patterns?—(13.) What are the means generally adopted to avoid cooling strains in castings?

THREE:Lawrence begged to differ. In the first place, he anticipated considerable entertainment. He was not selfish, he said, and had no desire to keep it to himself."Why, what's this?" he exclaimed. "What does the game mean?"