OF ARTS AND SCIENCES. 



257 



Table VIII. The columns give a number for reference, the result for 

 a Aquilce taken from Table VII., that for a LyrcB, and that given by 

 Dr. Iluggins for all stars of this class. 



TABLE VIII. 



The distinctive feature of these spectra is a series of broad dark 

 lines at regular intervals. The lines of greater wave-length appear to 

 coincide with the hydrogen lines, and the interval between the succes- 

 sive lines continues to diminish with the wave-length. Twelve of 

 these lines are photographed by Dr. Huggins. To these we should 

 add the lines F (4861) and C (6562), which are beyond the limits of 

 the photograph. The first and second lines are not contained in Dr. 

 Draper's photographs, as his plates were not sensitive to rays of such 

 short wave-length. Line 10, which appears to coincide with K of the 

 solar spectrum, is as strong as the others in a Aquilce, but in every 

 photograph of a Lyrce was marked as faint. In one case in Plate 30 

 it was overlooked. This photograph was over-exposed in this part of 

 the spectrum, but a more careful examination shows that the line is 

 probably present. Line 10 was only noticed in Plate 42. 



The resemblance of the spectrum of a Aurigce to that of the Sun has 

 already been noted ; a Boot is appeared to belong to the same class, but 

 the identity of the lines was not perceived until the measurements had 

 been reduced. It then became obvious that this star also has a spec- 

 trum closely resembling the Sun. The comjjarison is made in Table 

 IX. The first and second columns are the same as in Table IV,, and 

 give a number for reference and the wave-length of the lines in the solar 

 spectrum. The next column gives the number of plates of the Moon 

 and Jupiter, on which each line was measured. .It therefore gives a 

 sufficiently good comparison of the relative prominence of each line. 

 The next four columns give for the Moon, for Jupiter, for a Aurigte, 

 and for a Bootis, the mean of the measured wave-length minus the 

 wave-length given in the second column. 



VOL. XIX. (n. S. XI.) 17 



