149 



tion of tlie anterior Hue liolding tlie cross line 

 displaced, aud tlie first effects are, on this account, 

 not those of a working in this C, but hy re-action 

 of a working in the posterior C. Here, beginning 

 at the rear end, it double twists the propeller false 

 ribs, bringing them on their iuner beariag. 



With the estabhshment of its primary section 

 the posterior wiuding-hne would move the poste- 

 rior cross-line end, but this is held fast, displaced 

 to the left, untn the anterior line is discharged ia 

 its primary section by the action of the primary 

 section of the " alternate line," when it displaces 

 its appropriate end of the alternate cross-Hne. 



In consequence of this delay the propeller true 

 ribs are, next after the double twisting of the pro- 

 peller false ribs, brought on to their inner bear- 

 ings, and even the bearer true and false ribs are 

 brought on to then* outer bearuigs (§ 53) while 

 the displacement is still maintaiued. 



At the discharge, which begins with the forma- 

 tion of the secondary section of the " alternate an- 

 terior -^dnding-line," the original posterior C is 

 discharged, ^'^V^:/a/7^, but it is ^only when the es- 

 tablishment of the piimary section of this " alter- 

 nate line " takes place, and discharges the original 

 anterior C, releasing the original anterior cross- 

 7^ 



