FORE:From utter confusion to extreme nihilism there was but a single step. This step was taken by Gorgias, the Sicilian rhetorician, who held the same relation towards western Hellas and the Eleatic school as that which Protagoras held towards eastern Hellas and the philosophy of Heracleitus. He, like his eminent contemporary, was opposed to the thinkers whom, borrowing a useful term from the nomenclature of the last century, we may call the Greek physiocrats. To confute them, he wrote a book with the significant title, On Nature or Nothing: maintaining, first, that nothing exists; secondly, that if anything exists, we cannot know it; thirdly, that if we know it, there is no possibility of communicating our knowledge to others. The first thesis was established by pushing the Eleatic arguments against movement and change a little further; the second by showing that thought and existence are different, or else everything that is thought of would exist; the third by establishing a similar incommensurability between words and sensations. Grote96 has attempted to show that Gorgias was only arguing against the existence of a noumenon underlying phenomena, such as all idealists deny. Zeller has, however, convincingly proved that Gorgias, in common with every other thinker before Plato, was ignorant of this distinction;72 and we may add that it would leave the second and third theses absolutely unimpaired. We must take the whole together as constituting a declaration of war against science, an assertion, in still stronger language, of the agnosticism taught by Protagoras. The truth is, that a Greek controversialist generally overproved his case, and in order to overwhelm an adversary pulled down the whole house, even at the risk of being buried among the ruins himself. A modern reasoner, taking his cue from Gorgias, without pushing the matter to such an extreme, might carry on his attack on lines running parallel with those laid down by the Sicilian Sophist. He would begin by denying the existence of a state of Nature; for such a state must be either variable or constant. If it is constant, how could civilisation ever have arisen? If it is variable, what becomes of the fixed standard appealed to? Then, again, supposing such a state ever to have existed, how could authentic information about it have come down to us through the ages of corruption which are supposed to have intervened? And, lastly, granting that a state of Nature accessible to enquiry has ever existed, how can we reorganise society on the basis of such discordant data as are presented to us by the physiocrats, no two of whom agree with regard to the first principles of natural order; one saying that it is equality, another aristocracy, and a third despotism? We do not say that these arguments are conclusive, we only mean that in relation to modern thought they very fairly represent the dialectic artillery brought to bear by Greek humanism against its naturalistic opponents.Milling relates to metal cutting with serrated rotary cutters, and differs in many respects from either planing or turning. The movement of the cutting edges can be more rapid than with tools which act continuously, because the edges are cooled during the intervals between each cut; that is, if a milling tool has twenty teeth, any single tooth or edge acts only from a fifteenth to a twentieth part of the time; and as the cutting distance or time of cutting is rarely long enough to generate much heat, the speed of such tools may be one-half greater than for turning, drilling, or planing tools. Another distinction between milling and other tools is the perfect and rigid manner in which the cutting edges are supported; they are short and blunt, besides being usually carried on short rigid mandrils. A result of this rigid support of the tools is seen in the length of the cutting edges that can be employed, which are sometimes four inches or more in length. It is true the amount of material cut away in milling is much less than the edge movement will indicate when compared with turning or planing; yet the displacing capacity of a milling machine exceeds that of either a lathe or a planing machine. Theoretically the cutting or displacing capacity of any metal or wood cutting machine, is as the length of the edges multiplied into the speed of their cutting movement; a rule which applies very uniformly in wood cutting, and also in metal cutting within certain limits; but the strains that arise in metal cutting are so great that they may exceed all means of resisting them either in the material acted upon, or in the means of supporting tools, so that the length of cutting edges is limited. In turning chilled rolls at Pittsburg, [141] tools to six inches wide are employed, and the effect produced is as the length of the edge; but the depth of the cut is slight, and the operation is only possible because of the extreme rigidity of the pieces turned, and the tools being supported without movable joints as in common lathes.
Sed ultricies
