69 



the cross-tractions of the body will be preserved, 

 but the lateral developments will be suppressed, 

 their effects being carried toward the front (or in 

 the snake, lower part) of the joint. 



Similar effects of passing over a portion of the 

 gathering to the alternate points would result/^'om 

 the attempt to force the socket motions brought on by 

 the working of the diagonal right posterior point 

 of application. And also even beginning with the 

 points which correspond to the final movement of 

 the primary sections of the winding lines, although 

 these last would require a subsequent adjustment 

 with the secondary sections, from having been car- 

 ried out in advance of the regular course of move- 

 ment. 



It is the rotary movements (a) and (b), § 37, i. e., 

 those ivhich accompany the formation of the secondary 

 sections of the winding lines, that produce the arches. 

 The movements across the joint from rear tofront, 

 (a ') {b ' ), i. e., those ivhich accompany the primary 

 sections in their special movement, that depress the 

 planes of the cross-lines and points of application. 



§ 73. Let us now look at the accompanying 

 formations along the lines of traction. In doing 

 this, we must bear in mind that the Hues of trac- 

 tion are not permanent lines, but exist by certain 

 4 



