G8 ANIMAL MECHANICS 



and it bears at the same time a certain portion of 

 the strain, and so each fibre alternately. The 

 third step of the process is making the yarns. 

 Warping the yarns is stretching them to a certain 

 length ; and for the same reason, that so much 

 attention has been paid to the arrangement of the 

 fibres for the yarns, the same care is taken in the 

 management of the yarns for the strands. The 

 fourth step of the process is to form the strands 

 into ropes. The difficulty of the art has been to 

 make them bear alike, especially in great cables, 

 and this has been the object of patent machinery. 

 The hardening, by twisting, is also an essential 

 part of the process of rope-making ; for without 

 this, it would be little better than extended paral- 

 lel fibres of hemp. In this twisting, first of the 

 yarns, and then of the strands, those which are 

 on the outer surface must be more stretched than 

 those near the centre ; consequently, when there 

 is a strain upon the rope, the outer fibres will 

 break first, and the others in succession. It is to 

 avoid this, that each yarn and each strand, as it 

 is twisted or hardened, shall be itself revolving, 

 so that when drawn into the cable, the whole 

 component parts may, as nearly as possible, resist 

 the strain in an equal degree ; but the process is 

 not perfect, and this we must conclude from ob- 

 serving how different the construction of a tendon 

 is from that of a rope. A tendon consists of a 



