56 



anterior line, then, tracing the sockets, as it pro- 

 duces the concaves of the alternate curve, and the 

 posterior line the balls, as it produces the alternate 

 convexes. 



The figure of 8 shape, as developed in the hall and 

 socket movement, one half by the ball and one half 

 by the socket, or, by the cutting of two contrary 

 hehces, seems to lie at the foundation of all locomotion^ 

 and perhaps of all kinds of motion, including that 

 of the final atoms, pressure and rotation being its 

 elements. This connection of an 8 shape with lo- 

 comotion has, we believe, been noticed by several 

 authors. 



§ 59. It will be noticed, further, that (§ 27j the 

 posterior part of each G, as formed by the leading 

 point of application (here the left anterior), is the 

 longest, being furthest from the originating point, 

 and consequently carries the greater number of 

 ribs. The anterior ribs of each convex, then, dis- 

 charge their inward turn causing a spring back- 

 ward (§ 47), against the action of the numerically 

 preponderating ribs of the posterior parts, which 

 discharge their outward turn, causing a spring for- 

 ward. The anterior ribs of each convex will then 

 take the role of lifting the section while the posterior 

 ribs drive it fortvard. 



