Page:The Kinematics of Machinery.djvu/107

as spur-wheels, are slightly disguised in a very transparent veil; others still are closely drawn together in the interior of solid bodies which in their exterior forms scarcely give any indication of them, as in the case of the curved discs which we shall shortly have to examine more closely; and others, lastly, such as those of the link-work mechanisms, are widely extended, encircling the "bodies to which they belong at a great distance, their branches indeed stretching to infinity, their outward forms quite undis- cernible. These all carry on, partly before the bodily eye of the student and partly before the eye of his imagination, the same never tiring play. In the midst of the distracting noise of their material representatives they carry on their noiseless life-work of rolling. They are as it were the soul of the machine, ruling its utterances the bodily motions themselves and giving them in- telligible expression. They form the geometrical abstraction of the machine, and confer upon it, besides its outer meaning, an inner one, which gives it an intellectual interest to us far greater than any it could otherwise possess.