SOLAR VORTICES AND MAGNETISM IN SUN SPOTS ABBOT. 333 



brought together iu the following table. I am indebted to Mr. Adams for 

 these measures and for many of the others given in this paper. Miss Burwell 

 and Miss Wickham hitve also assisted in the measurement of the spot and spark 

 photographs. 



Table I. — Iron douhU'tx. 



The first column gives the wave length of the doublet ; the second, the separa- 

 tion in Angstroms of the components, observed along the lines of force in a 

 field of about 15.000 gausses ;<» the third, the quantity given in column 2 divided 

 by 5.1 ; the fourth, the separation of the components observed in the spot spec- 

 trum ; the fifth, the residuals obtained by subtracting the quantities iu the 

 third column from those in the fourth; the last column gives the ratio of the 

 separation in the spark, for a field of about 15,000 gausses, to the observed 

 separation in the spot. The mean value of this ratio, 5.1, gives an approximate 

 measure of the strength of the field in spots, which comes out about 2,000 

 gausses. 



The agreement between the spot and laboratory results is so close that it 

 can hardly be the result of chance. But when we come to the case of titanium, 

 observed in the laboratory in a field of about 12,500 gausses, we find a very 

 different condition of affairs. 



Table II. — Titanium douhlets. 



If we use the factor 5.1 employed in the case of iron, we find that two of 

 these doublets, \ G064.S5 and \ 6303.98, agree closely in spot and spark. In 

 some of our spot photographs \ 6064.85 appears to be a triplet, though the 

 components are not clearly separated. With the rhomb and Nicol a faint cen- 

 tral component persists when either the red or the violet component is cut off. 

 It is possible that this central line is due to some substance other than titanium 

 in the si>ot, but it is certainly very nearly in the position of the solar titanium 

 line * \ 6312.46 gives a residual of 0.03 Angstroms, which exceeds the error 



" This value of the field strength may be in error by 1,000 gausses, because of 

 the disturbing effect of the iron electrodes. 



* It is conceivable that under conditions analogous to those that give rise to 

 the Hs and Ks lines, a doublet might be produced within the strong magnetic 

 field of the spot, and a single line, at the center of the doublet, by the absorption 

 of the vapor at a high level, where the field strength is low. 



