ATTITUDES. 



445 



The other deductions to be made from the vertical ab lead to 

 results of more practical value : 



This line is, in fact (Fig. 148), equi- 

 distant from the two perpendiculars to 

 the ground, ef, gh, which can also be 

 demonstrated by observations on anim'als 

 selected as the types of good conforma- 

 tion. It is also equidistant from rs and 

 tu, the thickness of the articulations at 

 these points being equal. 



It follows from this that ab intersects 

 eg (the humerus) in its middle, as well 

 as rt ; for eghf and rtus are trapeziums 

 in which ab is parallel to and equidistant 

 from their bases. 



It is also seen that if gc (radio- 

 metacarpal segment) remain vertical, fh 

 (a horizontal projection from the hume- 

 rus) equals fb (projection of ae) plus bh 

 (projection of be). And as bh equals fb, 

 it can be said that the horizontal projec- 

 tion from the humerus is double the 

 horizontal projection of the phalangal 

 segment. 



Let us remark, finally, that all the 

 conclusions drawn from these typical 

 axes are always applicable, with the 

 sole condition that the articular angles 

 maintain their summits upon the lines 

 ef and gh. 



This proves that any articular angles 

 whatsoever can be compatible with good 

 axes. Here, also, the theory of General 

 Morris, which has been advanced 1 as an 

 excellent criterion to judge of the regu- 

 larity of the axes, is evidently defective. 



The knowledge of the fact that 

 the vertical line ab divides the hu- 

 merus as well as the distance rt into 

 two equal parts already constitutes 

 a factor which simplifies the appre- 

 ciation of the mode of equilibrium 

 of the fore part of the body ; for 

 instead of lowering, from the points e and g or r and i, two perpendic- 



FlG. 148. 



1 A. Sanson, loc. cit., p. 685. 



