TABER. — ON SINGULAR TRANSFORMATIONS. 597 



Parameter group discontinuous ; also group 



9 9 9 9 9 3d 



9 Xi 9 x 2 9 x 3 9 x 1 "9 x 2 9 x s 9 x± 

 t« P vr'i &» X ^ = ^ Xs) = ( X » X ^ = °' 



lype i. | ( Yij A;) ^ ^ ^ a;) ^ Qj ( ^ ^ __ a 



A a = 1. 



All groups of this type are continuous. 



P. S. Since what precedes was written, I have found that the infin- 

 itesimal transformations of the parameter group, given in equations (13), 

 § 2 (from which follow the differential equations (16), §3), had already 

 been obtained by Schur and Engel ; and that to Engel is due the deter- 

 mination of the values of the o's for which A a = 0. See Lie : Trans- 

 fer mationsgruppen, III, pp. 7 GO, 794. 



June 8, 1900. 



