527 
It is apparent at a glance that the circlets lie for the greater part 
below, the full dots above the curve A of the mean displacements. 
4000 4500 5000 5500 6000 
o 
R mean limb-centre displacements (Adams), 
o lines with companion on the red side, 
e lines with companion on the violet side, 
C mean centre-arc displacements (different observers), 
G gravitational displacement according to the general relativity theory. 
The average departure from the curve is — 0,0017 A for the 26 
circlets, + 0,0015 A for the 24 dots. 
Small as these departures are, yet they are most significant. 
To prove this we shall calculate what would have been the pro- 
bability of finding mean departures of this order of magnitude, if no 
systematic influence were at work. 
The 50 selected cases gave 21 points lying above, 29 points lying 
beneath the curve A of the general mean displacements. The sum 
of their positive departures was + 0,0472, that of their negative 
departures —0,0547; so the group, as a whole, gave a sum of 
— 0,0075 A, which involves that, on the average, the group lay 
0,0075 
250 
for the 450 lines. 
Taking the sum of all 50 departures (irrespective of signs) which 
34* 
—0,00015 A beneath the curve R of the general means 
