352 



ANIMAL MECHANICS. 



would be the mechanical equivalent of the skew muscle, pro- 

 vided it be so placed between the bones as to make 



I am, therefore, at liberty to make a second assumption, for 

 the purpose of fixing the other end of the fibre, and so render 

 the Problem of drawing an equivalent fibre definite. 



I choose a point 0, on the bone AB, determined on the 

 same principle as the point 0', viz. : — 



p ' 



and if from this point I draw a fibre to A'B', satisfying the 

 condition (105), the fibre joining 0 and 0', and having the 

 united force of all the fibres, will be mechanically equivalent 

 to the entire skew muscle. 



But the single equivalent fibre 00\ so found, will not 

 satisfy the Postulate (p. 238), unless its extremities lie in a 

 plane perpendicular to the axis of rotation, and at equal dis- 

 tances from that axis {vide p. 324) ; from which it readily 

 follows that, if the Postulate be true, the points 0 and 0' must 

 lie at equal distances from the socket of the hip joint. 



Let us proceed to inquire whether this be so or not. 



Determination of the single Fibre equivalent to a Skew 

 Muscle. 



1. Llama — Adductor secundus (j3). — In the case of the 

 Llama, we have, for four fibres, 



2 (J) - + o. 7 86 



2 (J) = + 4.007. 



