FORE:The second plan of boring by means of a bar mounted on points or centres is one by which the greatest accuracy is attainable; it is like chuck-boring a lathe operation, and [138] one for which no better machine than a lathe has been devised, at least for the smaller kinds of work. It is a problem whether in ordinary machine fitting there is not a gain by performing all boring in this manner whenever the rigidity of boring bars is sufficient without auxiliary supports, and when the bars can pass through the work. Machines arranged for this kind of boring can be employed in turning or boring as occasion may require.Machines do not create or consume, but only transmit and apply power; and it is only by conceiving of power as a constant element, independent of every kind of machinery, that the learner can reach a true understanding of the nature of machines. When once there is in the mind a fixed conception of power, dissociated from every kind of mechanism, there is laid, so to speak, a solid foundation on which an understanding of machines may be built up.