434] THE THEORY OF SCREWS IN NON-EUCLIDIAN SPACE. 481 



It seems at first sight incredible that a theorem demonstrated with such 

 simplicity should be of so much significance. It is not too much to say 

 that the theory of Rigid Dynamics in non-Euclidian space depends, to a 

 large extent, upon this result. This is the second of the two fundamental 

 theorems referred to in 396. 



These two principles open up a geometrical Theory of Screws in non- 

 Euclidian space. This is a subject too extensive to be here entered into any 

 further. It is hoped that the present chapter will at least have conducted 

 the reader to a point from which he can obtain a prospect of a great field of 

 work. The few incursions that have as yet been made into this field (see the 

 bibliographical notes) have shown the exceeding richness and interest of a 

 region that still awaits a more complete exploration. 



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