Certain Determinant Identities Arrived at hy H. v. Koch. 105 
and we have only to think of the determinants, which the C's and B's 
represent, to recognise the result as a familiar theorem regarding an 
aggregate of products of pairs of determinants often associated with 
Sylvester's name, but dating much farther back in the history of the 
subject. 
(11) Although Koch's identities are thus seen to be rediscoveries, it is 
equally clear that his method of arriving at them is his own, and is well 
worthy of study. 
EONDEBOSCH, SoUTH AfRICA, 
March 9th, 1919. 
