286 
PAUL BIEFELD 
In the judgment of the writer the above statements are hardly 
conclusive. Similar findings were reported by Prof. St. John of 
Mt. Wilson in the Astrophysical Journal Vol. 41, p. 62, 1915. 
And Prof. St. John in a private communication to the writer 
says quite correctly : ‘‘Curtis’ results showed the long recognized 
difficulty that strong (high-level) lines of iron show a shift to the 
red greater than the Einstein prediction, and the weak lines (low- 
level) a red displacement smaller than that required by relativity. 
This is at the center of the disk and the small differences from 
calculated values taken care of by radical currents of small 
cosmic velocities, upward near the photosphere and downward 
at very high levels, I see no way in the absence of pressure to 
account for these displacements without calling in relativity. At 
the edge of the disk the currents are no longer in the line of 
sight. The result at the limb is then a red displacement for both 
strong and weak lines of the full relativity value and a little more, 
this small excess being taken care of by differential scattering 
which produces a slight asymmetry on the red edge. There is no 
interpredation that will account for the red displacement at the 
limb, other than relativity.” 
These words coming from the greatest authority of solar spec- 
troscopy in America and one of the greatest in the world, leaves 
hardly any doubt that also this last prediction has stood the ex- 
perimental test of astrophysics. 
The test of this prediction and a confirmative outcome is of 
especial importance for two reasons. The first is, that Einstein 
himself maintains that ‘his whole theory of gravitation stands 
or falls by the success or failure of this test’ ; second that, as 
Eddington has pointed out, ‘if the displacement of solar lines be 
confirmed, it will be the first experimental evidence that Relativ- 
ity holds for quantum phenomena.’ 
Now a last word as to ‘gravitation’ itself. Newton assumed 
‘absolute space’ and ‘matter’ essential and besides this the con- 
cept of force acting between any two portions of matter in space. 
He himself has said, that it is absurd to think of force acting be- 
tween two bodies through empty space; but the inverse square- 
law works, to at least a very close degree of approximation, but 
it nevertheless remains ‘unreasonable.’ In Einstein’s theory 
‘gravitational force’ has no place as a fundamental concept! It 
is the ‘gravitational field’ analogous to the electrical and mag- 
