ERRATA. 



Vol. XV. page 469, line 6 from bottom, the expression in brackets ■[ ]- should 

 raised to the nth power. 



Vol. XV. p. 486, in equation (1) for ^ read ~. 



The equation which occurs at the foot of page 488 is Umited to the case whei 

 a—x-\-Sb const. 



Vol. XV. page 497, Hne ].2 from bottom, /or +0'00631 read +'000631. 



