198 CARNEGIE INSTITUTION OF WASHINGTON. 



(27) Large positive radial displacements are associated with low 

 heights above the photosphere and large negative displacements 

 with great heights, when a comparison is made between radial dis- 

 placements and elevation deduced from eclipse results. 



(28) The mean radial displacement of lines of the reversing layer 

 occurring frequently in flash spectra is +0.009 A; of those observed 

 less frequently it is +0.023 a. 



(29) A comparison of the radial displacements with the weakening 

 and strengthening of spot lines shows that strengthening increases 

 with depth and that weakening is associated with high elevations. 



(30) A discussion of the displacements between the center and 

 limb f if the sun from the point of view of levels indicates that pressure 

 plays the predominating role, but that the effect is modified by the 

 scattering of light in the lowest levels and by the downward move- 

 ment of the high-level vapors. 



(31) When the Mount Wilson rotation results are compared with 

 the corresponding radial displacements, a remarkable agreement is 

 found. Low values for solar rotation are associated with large 

 positive radial displacements, and high values for rotation with large 

 negative radial displacements. The data in both cases place the 

 level of the lanthanum lines below and the level of the hydrogen 

 lines above the mean level of the reversing layer. 



(32) Different lines give widely different field-strengths for the 

 magnetic fields of sun-spots, but when the lines are assigned to the 

 relative levels indicated by their radial displacements the field- 

 strength decreases consistently with elevation. 



(33) Judged by the criteria which indicate the presence of anoma- 

 lous dispersion, the radial displacements in the penumbrse of sun- 

 spots are not due to this cause. 



(34) A critical investigation of 53 international secondary stand- 

 ards shows no errors in relative wave-length exceeding 0.002 A. 



(35) The secondary standards belong to pressure groups a,b, c4, c5, 

 and sub-d, and the qualit}^ of the lines of the several groups is in 

 the order given. 



(36) It would be a gain if all the lines of group suh-d could be re- 

 placed by lines of better quality. This is feasible for the region 

 X 5192-X 5324, where excellent lines of group a are well distributed. 



(37) From a comparison of the measured intervals between close 

 pairs of lines, it appears that the wave-lengths of the components can 

 not be determined with sufficient accuracy to fit them for standards. 



(38) In the case of reversed lines, the measurements made upon 

 the sharp reversals are the most reliable. 



(39) The change in relative wave-length between Pasadena and 

 Mount Wilson, caused by difference in atmospheric pressure, is less 

 easy to substantiate in the blue-green than in the red region, but it 

 appears distinctly in the means. 



