once that as a rule there is a certain inclination to treat it as a piece of architecture, with which it certainly has in common the property of rest or immovability, and in the neighbourhood of which also it is often placed. The stationary parts of mechanisms have often attracted the attention of theorists. We have already seen this in the Introduction (p. 10) in Borgnis' division of the
Fig. 11.
parts of machines, where the "supports" figure as a class by themselves. Another indication of the same feeling is to be found in the division which so often occurs of the parts of machines into "active" and "passive." The latter are nothing else than the elements connected with those links of a kinematic chain which are, for the time, fixed. No absolute distinction exists however between
