9. Table X contains a summary of the results, for line centers only. Successive columns give the name of the star, the spectral class, the absolute magnitude, and the drop in magnitudes from background to line center, for the spectrum lines mentioned at the heads of the columns. The greater line depth for absolutely brighter stars, at least among those of the second type, is especially to be noted. TABLE X DROP IN INTENSITY, FROM BACKGROUND TO LINE CENTER, FOR ELEVEN STARS, EXPRESSED IN STELLAR MAGNITUDES ┌──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┐ │ Star │Class │ M │ Hβ │ Hγ │ Hδ │ Hε │ K │ 4227 │ 4215 │ ├──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤ │ε Ori │ B0│ │ .23│ .40│ .37│ .32│ │ │ │ │ß Ori │ cB8│ 5:│ .22│ .45│ .43│ .46│ .17│ │ │ │α Lyr │ A0│ 0.6│ .95│ 1.43│ 1.60│ 1.68│ .23│ │ │ │α CMa │ A0│ 1.2│ .96│ 1.39│ 1.46│ 1.47│ │ │ │ │α Cyg │ cA2│ 4:│ .33│ .63│ .63│ .70│ .54│ │ │ │α Aql │ A5│ 2.4│ .71│ .81│ .71│ 1.50│ .79│ │ │ │δ Cas │ A5│ 1.6│ 1.49│ 1.46│ 1.54│ 2.15│ 1.48│ │ │ │δ CMa │ cF8│ 3:│ .61│ 1.12│ .86│ >2.25│ >2.25│ .70│ .51│ │α Aur │ G0│ 0.0│ .43│ .76│ .57│ 1.62│ 1.67│ .57│ .36│ │α Boo │ K0│ 0.3│ │ .54│ .74│ │ │ 1.34│ .70│ │α Cas │ K0│ 0.0│ .25│ .42│ .56│ 2.50│ 2.47│ .83│ .71│ └──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘ 10. The material contained in Table X is reproduced in Table XI, where the intensity at the line center is expressed in terms of percentage of the background intensity, instead of in stellar magnitudes. The “background intensity,” as defined in Section 6, is the intensity that the background would have if the line were not present. It is noteworthy that, for the great majority of the lines, the residual intensity at the line center is greater than 30 per cent of the background intensity. 11. The material presented above constitutes the first systematic study of the contours of strong absorption lines. In view of the preliminary nature of the work the discussion has been devoted for the most part to presentation of method. Extended discussion seems at present to be premature, and only a few points need be mentioned.