695 
15. Addendum. 
In this paper the product i.i=x of the system R,°') is used. 
x can be found from the dualities existing in the orthogonal group, 
on which the identifications used in the system &,,° are founded. 
Now in investigations on differential geometry these identifications 
(e.g. of i, and ii) are practically not used. In this case it is 
convenient to substitute x by + 1, then x vanishes in all formulae, 
and the calculation grows much easier. It has however to be 
noted, that taking +1 for x it is no longer permitted to make use 
of the identifications founded on the dualities of the orthogonal group. 
1) J A. ScHoureN, On the direct analyses of the linear quantities etc., These 
Proceedings 21 (17) 327—341; Die Zahlensysteme der geometrischen Gröszen, 
Nieuw Archief (20) 141—156. 
