676 
PROFESSOfl J. R. LOCKYER ON THE PHOTOGRAPHIC 
* 
(4) Sub-division c . 
Characteristics of the spectra. 
VI.—Discussion of Stabs in Table B. 
(1) Suh-division a . 
Characteristics of the spectra.. 
(2) Slib-division /3. 
Characteristics of the spectra. 
Further sub-division into two sub-classes. 
Carbon absorption. 
VII.—Discussion of Stars in Table C. 
(1) Sub-division a . 
Characteristics of the spectra. 
The dark flirtings in these stars. 
Detailed discussion of the spectrum of a Orionis. 
Bright flutings. 
Sequence of spectra of these stars. 
(2) Sub-division (i ... 
Characteristics of the spectra. 
Possible variation in the spectrum of a Tauri. 
VIII.—The General Sequence of the Spectra op the Stars now under discussion . 
(1) Sequence of sub-divisions . 
Two series of spectra. 
(2) Variations observed . 
TX.—Discussion of Results in Relation to the Meteoritic Hypothesis . . . . 
(1) Phenomena to be expected on the hypothesis . 
Reference to classification based on eye observations. 
The complex origin of the spectra of Nebulre. 
The passage to bright line stars. 
Stars of increasing temperature. 
The hottest stars. 
Stars of decreasing temperature. 
(2) The actual phenomena recorded on the photographs . 
Nebulie. 
' Bright line stars. 
Stars of increasing tempeiature. 
The hottest stars. 
Stars of decreasing temperature. 
(3) Relation of the Groups to the Tabidar divisions . 
The ascending series (Groups I. to IV.). 
The hottest stars (Group IV.). 
The desceuding series (Groups IV. to VI.). 
(4) Extension of the original classification . 
Formation of sub-groups .. 
Sub-division into species. 
Diagrams.— 
Fig. 1.—Objective prism of 45° attached to 6 -inch object-glass. 
Fig. 2.—Objective prisms of 7^° each attached to 10-inch object-glass. 
Fig. 3.—Electrici control for driving clock of 10-inch equatorial. 
Page 
698 
698 
698 
698 
698 
699 
699 
700 
700 
701 
701 
701 
702 
703 
704 
705 
706 
706 
706 
707 
707 
707 
.708 
709 
709 
709 
710 
711 
711 
712 
712 
713 
713 
714 
716 
719 
720 
722 
722 
723 
724 
724 
724 
726 
679 
680 
682 
