30 



meeting of the primary sections of tlie two diag- 

 onal winding lines. It will be observed that the 

 secondary sections terminate each respectively at 

 what will be the point of application of the alter- 

 nate opposite line."^ 



§ 26. We shall designate each of the four wind- 

 ing Hnes by naming its point of departure which, 

 since their courses are entirely distinct, will fully 

 distinguish it thus : Upper lejt luinding line — loiver 

 right ivinding line — Upper right ivinding line — lower 

 left ivinding line. 



§ 27. As regards the concaves produced by the 

 revolution of a single point of apphcation against 

 the simple passive resistance of its diagonal point, 

 those concaves more directly under the active 

 point will be the deepest and shortest, and in each 

 C there ivill he two gradations of curvature, of 

 lohich that most remote from the active point ivill he 

 the longest and least sharply inflexed. This last 

 point is of considerable moment. 



§ 28. So soon as either one of a pair of diagonal 

 forces, drawing on its winding line, meets a cer- 

 tain amount of resistance through the cross-line, 

 whether from the active working, or the passive 

 resistance of the other point, its traction will be- 



* To complete this section see note, § 39, and particularly § 201. 



