59 



theii" bearers and receiving the proper lift from 

 tliem, quitted the ground first ; then these bearers ; 

 next, the ribs of the front C, in the same order. 

 Now, as, in this way, the rear C alters its curva- 

 ture before the front C, and this alteration com- 

 mences at its rear, the alternate propellers of the 

 rear C will, the first, be read}^ to take the ground, 

 then its bearers ; and in the same order for the 

 fi'ont C — that is, the new appuis will ground in 

 the same order that the old ones lifted. To ac- 

 complish this, we suppose the gathering "en air" 

 must have proceeded as far as the drawing of the 

 right (alternate) point of aj^plication upon the an- 

 terior end of the alternate cross-line, and the pass- 

 age of the head-ball pressure to the front. (§ 48.) 

 But, there are two conditions which may cause 

 the anterior C to reach the ground in advance of 

 the rear C. 1st. If the bearers of that C have not 

 sufficiently raised it, in which case, even if the 

 propellers of the front C should land before the 

 bearers, the anterior Hne-gathering w^ould be made 

 on the ground, and in a somewhat awkward man- 

 ner ; 2d. If the spring approach the nature of a 

 jump, and the gathering "en aii'" proceed as far 

 as the commencement of the active workmg from 



