34 



line toward its own side. This displacement of 

 tlie upper end of the cross-line will check the simi- 

 lar movement of the lower end to the opposite side, 

 when the diagonal lower point of apphcation acts. 

 Consequently when the "lower point of apphca- 

 tion," forming its "secondaiT section" first, has 

 prepared the upper C for discharge, by introduc- 

 ing into it a counter-ti'action and twist, and, next, 

 comes to form its own " piimary section," by mov- 

 ing the lower end of the "cross-line," it will find 

 this end immoveably fixed, and the forces gen- 

 erated by its rotation will thus be brought to bear 

 against the appui of lower end of the rod on the 

 ground^ (not against the cross-line) and be kept 

 against the groimd imtil the last moment of the 

 general discharge, when only, the lower end of 

 the cross-line may be moved. 



Thus, the upper C being discharged, the lower C 

 will immediately follow, the latter acting, not 

 against the cross-hne, but in hannony with the 

 upper C against the upper terminal plane. 



§ 33. The point of appui on the groimd for the 

 lower end will be on the side to which the whole 

 cross-line is maintained diu'ing the action, /. e., the 



* If the lower cioss-line end be Hxecl to the left, this appiu will be 

 on the left side, and vice versa. 



