- Software name: appdown
- Software type: Microsoft Framwork
- size: 61MB
In like manner, Lucretius rejects the theory that living bodies are made up of the four elements, much as he admires110 its author, Empedocles. It seemed to him a blind confusion of the inorganic with the organic, the complex harmonies of life needing a much more subtle explanation than was afforded by such a crude intermixture of warring principles. If the theory of Anaxagoras fares no better in his hands, it is for the converse reason. He looks on it as an attempt to carry back purely vital phenomena into the inorganic world, to read into the ultimate molecules of matter what no analysis can make them yieldthat is, something with properties like those of the tissues out of which animal bodies are composed.
The art of keeping reasonably clean even in a machine shop is worth studying; some men are greased from head to foot in a few hours, no matter what their work may be; while others will perform almost any kind of work, and keep clean without sacrificing convenience in the least. This difference is the result of habits readily acquired and easily retained.
Designing is in many respects the same thing as invention, except that it deals more with mechanism than principles, although it may, and often does include both. Like invention, designing should always be attempted for the attainment of some definite object laid down at the beginning, and followed persistently throughout.
"I'll take them off your hands and give you a cheque," said Isidore. "I shall want a lot of notes in the morning."In planing and turning, the tools require no exact form; they can be roughly made, except the edge, and even this, in most cases, is shaped by the eye. Such tools are maintained at a trifling expense, and the destruction of an edge is a matter of no consequence. The form, temper, and strength can be continually adapted to the varying conditions of the work and the hardness of material. The line of division between planing and milling is fixed by two circumstancesthe hardness and uniformity of the material to be cut, and the importance of duplication. Brass, clean iron, soft steel, or any homogeneous metal not hard enough to cause risk to the tools, can be milled at less expense than planed, provided there is enough work of a uniform character to justify the expense of milling tools. Cutting the teeth of wheels is an example where milling is profitable, but not to the extent generally supposed. In the manufacture of small arms, sewing machines, clocks, and especially watches, where there is a constant and exact duplication of parts, milling is indispensable. Such manufactures are in some cases founded on milling operations, as will be pointed out in another chapter.