254 CARNEGIE INSTITUTION OF WASHINGTON. 



DISTRIBUTION OF ELEMENTS IN THE SOLAR ATMOSPHERE 

 FROM ECLIPSE DATA. 



A discussion, by Mr. St. John, of Mitchell's eclipse data from the 

 standpoint suggested b}^ his investigation of radial motion in sun-spots, 

 confirms Mr. St. John's previous conclusions in several points. The 

 lengths of arc in the flash spectrum indicate the highest levels for the H 

 and K lines of calcium, followed by the hydrogen lines, while the heavy 

 elements and carbon appear only in the lower portion of the solar 

 atmosphere, in complete accordance with the radial-motion results. 



The radial displacements of the iron hues, arranged according to solar 

 intensities, furnish a scale of relative levels which is confirmed by the 

 eclipse data, thus supplying the means of translating relative into 

 absolute elevations. A statistical study of C66 flash lines shows that 

 the elevations are less for lines in the red than for lines of the same 

 solar intensity and of shorter wave-lengths, in harmony with the radial- 

 motion results. 



Weakness of solar lines or lowness of level in the solar atmosphere 

 is associated with strong flash intensities relative to the Fraunhofer 

 lines, of which the flash lines are the reversals. A seeming disagree- 

 ment regarding carbon, lanthanum, and cerium, placed by Mitchell 

 above iron because of their longer arcs, finds an explanation in the 

 increased flash intensity of these low-level lines due to the higher 

 temperature at the lower level. This causes their arcs to be traced to 

 a greater distance than in the case of iron lines of the same flash 

 intensity and accounts for three-fourths of the excess. 



The heights reached by enhanced lines are greater than for unen- 

 hanced lines of the same solar intensity, in agreement with the adopted 

 interpretation of radial displacements. The discussion brought out 

 the following additional facts relative to enhanced lines in the chromo- 

 sphere: the intensity of enhanced lines relative to that of the solar 

 lines increases with the intensity of the solar lines instead of decreasing 

 as for unenhanced lines; the greater the heights given by the unen- 

 hanced lines, the greater the intensity relative to that of the solar line, 

 which is opposite to the course for unenhanced lines; there seems to 

 be no relation between the degree of enhancement in arc and spark 

 and the heights in the chromosphere; an intensifying of the enhanced 

 lines has been assumed to be brought about by the atmosphere of 

 hydrogen obtaining in the sun, but a comparison of the enhancement 

 of lines that occur in an atmosphere of hydrogen with the eclipse data 

 shows no relation between the two phenomena; the behavior of the 

 enhanced lines in the chromosphere appears to be in entire harmony 

 with the enhancement of the spark lines that occur under reduction 

 of pressure, an explanation suggested by Gale and Adams when dis- 

 cussing the enhancement of the spark lines of titanium under decreased 

 pressure. 



