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KANSAS UNIVERSITY ()UARTERLV. 



This result is also obtained from the expressions (lo) and ( 1 1 ). 

 For k^=oc the first indicates that the center of the circle (8) is at 



Fig. H. 



an infinite distance in a direction whose trigonometric tangent is 



j b-j-ak + al i-|~k2 I a 

 lim -: '- r= . 



La— bk— hi i+k3 i k=x b 

 The second expression gives for the co-ordinates of the circle (g) 



a b 



2 2 



