( 363 ) 
differing from the condition 
which we have found as a necessary consequence of hypothesis H. 
This proves sufficiently that in reality Arry’s method (at least if 
his equations of condition are treated with least squares) does not 
agree with hypothesis Z. 
A few examples will show this still more clearly and will at the 
same time prove that the application of conditions (9) and (18) may 
lead to very considerably different solutions. 
1st example (see fig. 3). In each of the two points of the celestial 
(A ig) \ 
Fig. 3. 
sphere S and S' we find two stars. The proper motions SA and SB 
of the two stars in S are equal and we will begin by assuming 
that their directions form an obtuse angle. The same holds for the 
stars in S', 
