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Ball — On the Character of the Linear Transfortnation. 537 



In conclusion, I may remark that this small communication is 

 another fragment of that research on the Dynamics of Elliptic Space 

 •which has for several years occasionally occupied my leisure thoughts. 

 The theory is one of very great extent, and it appears to me to he so 

 replete with mathematical interest, that I sometimes cherish the hope 

 of rewriting the -'Theory of Screws," with those generalized concep- 

 tions of measurement which hare been introduced by the genius of 

 Cayley. Many most valuable contributions have been made to the 

 theory in the last few years by Mr. Heath, by Mr. Homersham Cox, 

 and especially by Mr. A. Buckheim. 



