(RE) 
absolute value of 2—1 to be greater at d, than at d,, the red 
component should be a little stronger than the violet one. St. Jonny, 
however, states*): “On the plates 1 mm. from the limb the emission 
components are very broad and strong, and, as far as the eye can 
judge, symmetrical”. But on measuring the width of the components 
on some 30 selected plates, he found the violet one on the average 
0,0074 A wider than the red one. Surely the difference is small, but 
if it proves to be genuine, not accidental, our theory cannot, in its 
present form, explain the phenomenon — unless we are just here 
perhaps concerned with the case of asymmetry of the dispersion 
curve, treated of in $ 3 of my former communication *). 
Another case in which our theory perhaps falls short, is the 
following. 
From published reproductions of spectrograms, obtained at Meudon 
and on Mount Wilson, I get the impression that the average distance 
between the brightest places of the A,-components is greater at the 
limb than on very bright floeculi and faculae situated e.g. halfway 
between centre and limb. Now, according to our explanation, the 
position of the brightest patches of the components ought to be almost 
entirely determined by the position of the points d, and d,, also in 
the spectrum of those brightest floceuli, because the part of the 
brightness which is due to the small intermediate tops of the R,-curve 
is relatively slight in flocculi. That is: we should expect A, in the 
spectrum of very bright flocculi and faculae to be on the average 
not less wide than at the limb’). If the study of original plates 
confirms our suspicion that in this case the results of the observation 
contradict the theoretical conclusions, we shall have to correct the 
theory, or, if that is impossible, to reject it. 
Finally attention must be called to some consequences resulting 
from the explanation given by DerSLANDRES, JEweLL and Sr. JonN of 
the phenomena exhibited by the A and & lines. 
Among the greatest difficulties into which we are led by ascribing 
the line-displacements in question to ascending and descending currents, 
is in my opinion the one, already mentioned in the beginning of this 
paper: How is it possible, that in those violent vertical hurricanes 
of calcium vapour prevailing over the general surface of the sun, 
other gases of the chromosphere are not involved at all? 
1) St. Jorn. |. ce. p. 54. 
2) Proc. Roy. Acad. Amsterdam, XIII, 885, (1911). 
3) In making the measurements, from which the gradual increase in width of 
K, and K3 on approaching the limb has been deduced, Sr. Jorn intentionally 
avoided the brilliant facular and floccular regions. Cf. l.c. p. 48 and 50. 
a ee 
