Intelligence and Miscellaneous Articles. 313 



vast convulsion taking place in this object, large quantities of gas 

 have been evolved from it, that the hydrogen present is burning by 

 combination with some other element and furnishes the light repre- 

 sented by the bright lines, also that the flaming gas has heated to 

 vivid incandescence the solid matter of the photosphere. As the 

 hydrogen becomes exhausted, all the phenomena diminish in inten- 

 sity, and the star rapidly wanes. 



In connexion with this star, the observations which we made upon 

 the spectra of a Orionis and /3 Pegasi, that they contain no absorp- 

 tion lines of hydrogen, appear to have some new interest. The 

 spectra of these stars agree in their general characters with the ab- 

 sorption spectrum of the new star. The whole class of white stars 

 are distinguished by having hydrogen lines of extraordinary force. It 

 may also be mentioned here that we have found that the spectra of 

 several of the more remarkable of the variable stars, namely those 

 distinguished by an orange or ruddy tint, possess a close general ac- 

 cordance with those of a Orionis, (3 Pegasi, and the absorption spec- 

 trum of the remarkable object described in this paper. The purely 

 speculative idea presents itself from these observations, that hydrogen 

 probably plays an important part in the differences of physical con- 

 stitution which apparently separate the stars into groups, and pos- 

 sibly also in the changes by which these differences may be brought 

 about*. 



XLI. Intelligence and Miscellaneous Articles. 



ON THE FIGURE OF THE EARTH MEASURED GEODETICALLY. 

 BY ARCHDEACON PRATT, M.A., F.R.S. 



To the Editors of the Philosophical Magazine and Journal. 



Near Alexandria, 

 Gentlemen, September 10, 1866. 



TT7T.TH reference to Captain Clarke's letter to you, which appears 



* ' in your Magazine for this month (September), and my paper 



in your July Number, I beg to say that, through inadvertence, or, in 



plain English, a blunder, I wrote down the wrong formula for my 



* Mr. Baxendell sends us the following Table of magnitudes : — 

 h m 

 May 15 at 12 G.M.T., r Coronae = 3*6 or 3*7 magnitude. 



16 „ 10 30 







= 4-2 



17 „ 11 



» 





= 4-9 



18 „ 12 30 







= 53 



19 „ 12 15 







= 5-7 



20 „ 12 30 



>» 





= 6-2 



21 „ 12 



»» 



>l 



= 73 



22 „ 11 15 





„ 



= 7-7 



23 „ 10 30 



>» 



»» 



= 7-9 



24 „ 10 30 



fl 



>> 



= 8-1 



