MECHANISM OF THE SPINE 33 



superior advantage gained in working the ship ; 

 the sails upon this mast act more powerfully in 

 swaying the vessel round, and the perpendicular 

 position causes the ship to tack or stay better ; 

 but the perpendicular position, as we have seen, 

 causes the strain in pitching to come at right 

 angles to the mast, and is, therefore, more apt to 

 spring it. 



These considerations give an interest to the 

 fact, that the human spine, from its utmost con- 

 vexity near its base, inclines backwards. 



