283 



MR. JOSEPH BAXENDELL ON THE 



tions respecting the causes of variability must be based 

 upon a consideration of the variations in the intensity of 

 the light, and not in the magnitude of the star, I have cal- 

 culated the relative intensities of the light of T Coronas 

 for every night of observation, taking the intensity of the 

 light of a loth magnitude star as unity. The results are 

 given in the following Table : — 





Intensities of the Light of T Coronse. 







Date. 



Mag. 



Intensity, 



10 mag. 



being = I "0. 



Date. 



Mag. 



Inten- 

 sity. 



Date. 



Mag. 



Inten- 

 sity. 



1866. 



















May 15 



37 



331-2 



June 17 



9-5 



1-6 



Sept. 17 



7-9 



6-9 



16 



4-2 



209"0 



19 



9-S 



1-6 



22 



7'9 



6-9 



17 



4-9 



i6o*o 



25 



9-6 



1-4 



24 



7-8 



7-6 



18 



5-3 



75-8 



26 



97 



1-3 



30 



7-8 



7-6 



19 



5-6 



57-5 



July II 



97 



i'3 



Oct. I 



77 



8-3 



20 



6-2 



33-i 



16 



97 



i"3 



6 



7-6 



9-1 



21 



7"i 



14-4 



19 



9-6 



I "4 



8 



7-6 



9-1 



22 



7*4 



II"0 



20 



97 



1-3 



10 



7-5 



lO'O 



^3 



7-5 



lo-o 



21 



9-6 



I "4 



14 



7-5 



lo-o 



24 



77 



8-3 



22 



9-5 



1-6 



19 



77 



8-3 



25 



7-8 



7-6 



30 



97 



1-3 



28 



7-8 



7-6 



26 



8-0 



6-3 



Aug. 20 



9-8 



1-2 



Nov. 6 



7'9 



6-9 



29 



8-4 



4-4 



27. 



9'S 



1-6 



19 



8-3 



4-8 



June 8 



9'3 



1-9 



31 



9"3 



19 









10 



9-2 



2-1 



Sept. 14 



7*9 



6-9 









16 



9'4 



17 



IS 



7-8 



7-6 









The outburst of T Coronae appears to have been first 

 observed by Mr. J. Birmingham of Tuam, on the night 

 of May 12, when its brightness was equal to, if not greater 

 than, that of a Coronae, the magnitude of which is 2'6. 

 The relative intensity of the light of the variable on that 

 night was therefore not less than Qia'i. Comparing this 

 with the intensities in the above Table, it will be seen that 

 during the first ten days of the starts appearance its light 

 diminished with extraordinary rapidity, the intensity on 

 the 22nd May being only ii-o against 912T on the 12th 

 when first seen by Mr. Birmingham, and 331*2 on the 

 1 5th when first seen by myself. Since the 22nd of May 



