14 THE THEORY OF SCREWS. [8 



If it be objected, that with so great a restriction as that just referred to, 

 only a limited field of inquiry remains, the answer is as follows : A perfectly 

 general investigation could yield but a slender harvest of interesting or 

 valuable results. All the problems of Physical importance are special cases 

 of the general question. Thus, a special character in the constraints has pro 

 duced the celebrated problem of the rotation of a rigid body about a fixed 

 point. To vindicate our particular restriction it seems only necessary to 

 remark, that the restricted inquiry still includes the theory of Equilibrium, 

 of Impulsive Forces, and of Small Oscillations. 



Whatever novelty may be found in the following pages will, it is 

 believed, be largely due to the circumstance that, with the important 

 exception referred to, all the conditions of each problem are of absolute 

 generality. 



