1904] Lines of Titanium, etc., in Fraunhoferic Spectrum. 263 



FRAUNHOFERIC LINES DUE TO p Ti, p Fe, or p Cr. 



The following table contains the Fraunhoferic lines which are, 

 as a result of the present discussion, considered to be due, either 

 wholly or partially, to enhanced lines of titanium, iron, or chromium. 

 Eowland's wave-lengths have been adopted with the modification that 

 the last figure in the decimals has been dropped, and the numbers 

 given to the nearest second decimal. In such an inquiry as the present 

 one, this can be done without affecting the validity of the results. In 

 the first place, the spark lines are generally of a wider and hazier 

 nature than the arc lines, and consequently their wave-lengths cannot 

 be estimated to as great a degree of accuracy. Again, the conclusions 

 as to the identity of the solar and enhanced lines are not based on one 

 or two coincidences only, but on the apparent agreement of a whole 

 series of lines for each element. 



It will be seen that some forty-two lines which were unorigined by 

 Rowland are here attributed to proto-titanium, proto-iron, or proto- 

 chromium. Compared with the host of lines in Eowland's tables 

 this may seem a very insignificant number, but the importance of 

 establishing their origins does not lie in their number, but in the fact 

 that they are lines of a special nature, and just those metallic lines 

 which are prevalent in the spectra of the higher temperature stars, such 

 as a Cygni and Sirius, to the exclusion of the great majority of the 

 other solar lines. 



The enhanced lines have previously been identified with stellar 

 lines, which in such stars as a Cygni, Sirius, and Eigel are of a more 

 isolated nature than in the solar spectrum, and if the same lines can 

 be established as occurring in the solar spectrum it at once standardises 

 the wave-lengths of many stellar lines, and will thus be of importance 

 in any stellar inquiry in which it is necessary to have accurate wave- 

 lengths for the spectral lines. 



In some cases it has been found that there is no justification for 

 the origin given by Eowland. These, however, are very few, and are 

 indicated in the notes appended. 



In others, Eowland's origin does not appear to be a sufficient one, 

 that is, the intensity of the solar lines cannot be adequately accounted 

 for by the lines of the elements to which he ascribes them. In such 

 cases it is probable that the solar lines are due partly to the arc 

 lines of the elements quoted by Eowland and partly to the enhanced 

 lines of either Fe, Ti, or Cr, which occur at or very near the same 

 wave-lengths. 



A glance at the table will show that for many lines the same element 

 is given in the two columns for origins, the Kensington origin having 

 the prefix "p." This simply means that there is an enhanced line 

 of that particular element at the given wave-length, which is not 



