180 



Mr. J. Norman Lockyer. 



for the D 3 line in the spectrum of Sirius was made by Mr. Fowler in 

 December, 1893, but the line was not seen in this star, although it 

 was recorded in the spectrum of Bellatrix.* 



So far as they go, then, the gradually disappearing lines of the 

 cleveite gases indicate the same order of temperature as that deter- 

 mined from the gradual appearance of the metallic lines as shown in 

 Map VII. 



IX. On the Absorbing Conditions on the Upward and Downward 

 Sides of the Temperature Curye. 



Temperature Order of some of the Hottest Stars on the two Sides of the 

 Temperature Curve. 



Utilising the new criteria which have now become available, some 

 of the brighter stars may be arranged as follows, those on the same 

 horizon being of equal temperature. 



These criteria, however, do not enable us to classify minutely the 

 stars which fall near the top of the curve, so, for the present, a 

 certain number which must be afterwards separated, are grouped 

 together. 



The stars which have been included in the maps are in italics. 



Increasing Temperature. Decreasing Temperature. 



{JBellatrix, £ Orionis, rj Ursa? Majoris, A Tauri, y Pegasi). 



£ Tauri. |3 Persei, 8 Cygni, o Pegasi, a Andro- 



meda?, a Corona?, y Ursa? Majoris. 



Rigel, & Tauri, 

 r) Leonis, 

 a Cygni. 



y Cygni, c Cephei, Polaris, a Persei, 

 £ G-eminorum. 



a Tauri, e Pegasi, y Andromedse, e Vir- 

 ginis. 



a Orionis, Pegasi. 



y Lyrce. 



a Canum Venaticorurn. 



Sirius, Yega, y Geminorum, 8 Leonis, 

 j8 Ursa? Majoris, e Ursa? Majoris. 



Castor, /S Arietis, a Cephei, a Aquila?, 

 d Cassiopeia?, & Cassiopeia?. 



Procyon. 



Arcturus (Sun), a Arietis, /3 G-emino- 

 rum. 



* ' Phil. Trans.,' vol. 186, A, p. 85. 



