Blended with the Si+++ line at 4096, which is probably effective throughout the whole range O+ 1 2 3 ? 4 ? 5 Blended with C++ line at 4649, which preponderates in stars hotter than , and probably contributes largely in that class 6 7 8 9 10 11 ? Certainly another line is here involved, but it has not been identified 12 13 14 S+ 1 2 3 Lines recorded by Lockyer; not measured by the writer S++ 4 Line recorded by Lockyer. Intensity from H.A., 28; not measured by the writer 5 6 Recorded by H. H. Plaskett in 10 Lacertae [Pg 208] V. MATERIAL BEARING ON THE CLASSIFICATION OF STARS, QUOTED IN CHAPTER XII IN illustration of the problem of Class , observations of sixty-two stars are collected in the following table. Successive columns contain the H.D. number, the name of the star, the apparent magnitude, the reduced proper motion , and the spectral class. Then follow columns which indicate the presence () or absence of metallic lines, the quality of the lines (sharp lines being represented by the letter and hazy lines by the letter ), the presence of wings to the hydrogen lines, and the strength of the Sr+ line at 4077 and the Si+ lines at 4128, 4131. [Pg 209] The stars in each class are arranged in order of increasing strength of metallic lines, and it will be seen that this feature is correlated with the strength of the silicon and strontium lines, but not with the line quality or the hydrogen wings, nor with the reduced proper motion. TABLE XXXIV H. D. Star m H Class Metalic Lines Line Quality H wings Sr+ Si+ 120198 84 UMa 5.53 6.4 x 9 10 108662 17 Com 5.38 2.7 x 7 8 170397 Br 2314 5.99 2.7 x h 6 9 133029 +47° 2192 6.16 - x h 5 11 140160 Ser 5.26 3.5 x 10 5 94334 Uma 4.34 3.6 x s 2 3 58142 21 Lyn 4.45 2.9 h - 4 192913 +27° 3668 6.69 - h ? 7 225132 2 Cet 4.62 1.2 h - 4 41841 89 Lep 5.50 2.2 - - 222661 Aqr 4.62 4.8 h - - 87887 15 Sex 4.6 1.9 - 5 213323 38 Peg 5.51 3.3 - - 25642 Per 4.33 2.2 - 4 114330 Vir 4.44 3.2 s - 3 109485 23 Com 4.78 4.1 s - 3 103632 Cra 5.16 3.8 x - - 110411 Vir 4.95 5.6 x - - 133962 k Boo 5.59 4.6 x - - 188260 13 Vul 4.50 2.5 h x - 4 124224 12 4.90 3.8 - 11 183056 4 Cyg 5.2 -0.4 - 9 183986 +35° 3658 6.04 - x - 5 196502 73 Dra 5.18 1.2 x s 12 10 148367 Oph 4.68 4.3 x s x 9 8 118022 78 Vir 4.93 3.5 x 10 9 182564 Dra 4.63 2.9 x 7 7 125337 Vir 4.60 -1.9 x h 7 6 214734 30 Cep 5.21 1.6 x 3? 5 7804 89 Psc 5.28 4.2 x x 5 7 220825 Psc 4.94 - x 6 7 72968 3 Hya 5.61 2.8 x 6 7 56405 Paris 8971 5.39 4.7 x s s 3? 6 20677 32 Per 4.98 3.8 x x - 5 [Pg 210] 48250 12 Lyn 4.89 1.8 x x - 5 107612 - Com 6.56 - x 9 - 18519,20 Ari 4.6 1.1 , s 3 3 107966 13 Com 5.10 2.7 - - 108382 16 Com 5.04 0.6 - - 108945 21 Com 5.39 1.9 x 11 9 108642 +26° 2138 6.48 - x 8 6 89904 27 Lmi 6.1 3.0 x h x 6 9 108651 +26° 2353 6.69 - x h 7 6 170296 Scu 4.73 -0.5 x h x - 7 115331 196 Cen 6.0 3.4