THREE:Lucretius has been called Romes only great speculative genius. This is, of course, absurd. A talent for lucid ex101position does not constitute speculative genius, especially when it is unaccompanied by any ability to criticise the opinions expounded. The author of the De Rerum Natura probably had a lawyers education. He certainly exhibits great forensic skill in speaking from his brief. But Cicero and Seneca showed the same skill on a much more extensive scale; and the former in particular was immensely superior to Lucretius in knowledge and argumentative power. Besides, the poet, who was certainly not disposed to hide his light under a bushel, and who exalts his own artistic excellences in no measured terms, never professes to be anything but a humble interpreter of truths first revealed to his Greek instructors vivid intellect. It has, indeed, been claimed for Lucretius that he teaches a higher wisdom than his acknowledged guide.195 This assertion is, however, not borne out by a careful comparison between the two.196 In both there is the same theory of the universe, of man, and of the relations connecting them with one another. The idea of Nature in Lucretius shows no advance over the same idea in Epicurus. To each it expresses, not, as with the Stoics, a unifying power, a design by which all things work together for the best, but simply the conditions of a permanent mechanical aggregation. When Lucretius speaks of foedera Naturai, he means, not what we understand by laws of nature, that is, uniformities of causation underlying all phenomenal differences, to understand which is an exaltation of human dignity through the added power of prevision and control which it bestows, but rather the limiting possibilities of existence, the barriers against which human hopes and aspirations dash themselves in vainan objective logic which guards us against fallacies instead of enabling us to arrive at positive conclusions. We have here the pervadingly negative character of Epicureanism,102 though probably presented with something of Roman solemnity and sternness. The idea of individuality, with which Lucretius has also been credited, occupies but a small place in his exposition, and seems to have interested him only as a particular aspect of the atomic theory. The ultimate particles of matter must be divided into unlike groups of units, for otherwise we could not explain the unlikenesses exhibited by sensible objects. This is neither the original Greek idea, that every man has his own life to lead, irrespective of public opinion or arbitrary convention; nor is it the modern delight in Natures inexhaustible variety as opposed to the poverty of human invention, or to the restrictions of fashionable taste. Nor can we admit that Lucretius developed Epicurean philosophy in the direction of increased attention to the external world. The poet was, no doubt, a consummate observer, and he used his observations with wonderful felicity for the elucidation and enforcement of his philosophical reasoning; but in this respect he has been equalled or surpassed by other poets who either knew nothing of systematic philosophy, or, like Dante, were educated in a system as unlike as possible to that of Epicurus. There is, therefore, every reason for assuming that he saw and described phenomena not by virtue of his scientific training, but by virtue of his artistic endowment. And the same may be said of the other points in which he is credited with improvements on his masters doctrine. There is, no doubt, a strong consciousness of unity, of individuality, and of law running through his poem. But it is under the form of intuitions or contemplations, not under the form of speculative ideas that they are to be found. And, as will be presently shown, it is not as attributes of Nature but as attributes of life that they present themselves to his imagination.Different kinds of gearing can be seen in almost every engineering establishment, and in view of the amount of scientific information available, it will only be necessary to point out some of the conditions that govern the use and operation of the different kinds of wheels. The durability of gearing, aside from breaking, is dependent upon pressure and the amount of rubbing action that takes place between the teeth when in contact. Spur wheels, or bevel wheels, when the pitch is accurate and the teeth of the proper form, if kept clean and lubricated, wear but little, because the contact between the teeth is that of rolling instead of sliding. In many cases, one wheel of a pair is filled with wooden cogs; in this arrangement there are four objects, to avoid noise, to attain a degree of elasticity in the teeth, to retain lubricants by absorption in the wood, and to secure by wear a better configuration of the teeth than is usually attained in casting, or even in cutting teeth.
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