April, igi2 fm m:^ Q 



■■''OF f'.C.' V. 



PROCEEDINGS 



OF THE 



ROYAL IRISH ACADEMY 



Volume XXIX, Section A, No. 6 



REGINALD A. P. ROGERS 



SOME DIFFERENTIAL PROPERTIES OF 

 THE ORTHOGONAL TRAJECTORIES OF 

 A CONGRUENCE OF CURVES, WITH 

 AN APPLICATION TO CURL AND 

 DIVERGENCE OF VECTORS 



DUBLIN 



HODGES, FIGGIS, & CO., Ltd. 



LONDON : WILLIAMS & NORGATE 



I912 



Price Sixpence 



