1364 
labs À bcd 
Xa = F4b = Waes 
laba daca 
YAa — Yaa — W bes 
ly As 
labs Aabe 
bike. 
Taking also into consideration the opposite side (dia, day, de) we 
find for X,, Xs, XN, the contributions 
Mar ayy, Othe yy ae ay, 
Ou, Oa, Ove 
This may be applied to each of the three pairs of sides not yet 
mentioned under a; we have only to take for c successively 1, 2, 3. 
Summing up what has been said in this § we may say: the 
components of the vector on the left hand side of (10) are 
IWad 
Oxy 
Via = Xba = Wace. 
dW, 
X,= 2 (6) 
§ 27. For the components of the vector occurring on the right 
hand side of (10) we may write 
1qa dQ, 
if qa is the component of the vector q in the direction x, expressed 
in w-units, while d2 represents the magnitude of the element 
(dx,,...dv,) in natural units. This magnitude is 
—iV—gdW, 
so that by putting 
Eid ity ie a a 
we find for equation (10) 
IWa 
Si)! uae es OS ee 
dx, 
The four relations contained in this equation have the same form 
as those expressed by formula (25) in my paper of last year’). We 
shall now show that the two sets of equations correspond in all 
respects. For this purpose it will be shown that the transformation 
formulae formerly deduced for wa and Woe follow from the way in 
which these quantities have been now defined. The notations from 
the former paper will again be used and we shall suppose the 
transformation determinant p to be positive. 
1) Zittingsverslag Akad. Amsterdam, 23 (1915), p. 1073; translated in Proceedings 
Amsterdam, 19 (1916), p. 751. Further on this last paper will be cited by 1.c. 
