37 
It will be seen that the brightness of the star diminished 
with great rapidity for several days after my first observa- 
tion, and afterwards more gradually, and that on the 26th of 
June it had sunk to the 9 '7 magnitude. It then remained 
with little change till about the 20th of August, when an- 
other rise commenced, and on the 15th of September it had 
attained the 7*8 magnitude. On the 10th and 14th of Octo- 
ber it ‘was of the 7'5 magnitude, and since the latter date 
its brightness has again slightly diminished. 
It will also be noticed that in the recent observations no 
mention is made of the blue tinge which formed so striking 
a feature in the colour of the star for some time after its 
first appearance. In connection with this the following 
extract of a letter from Mr. Huggins, F.R.S., dated October 
13th, will be interesting to the members of the Society. 
Referring to T Coronse the writer says, “I observed its 
spectrum on September 16th, 27th, 28th, and October 8th. 
The bright lines are not now to be distinguished. If they 
exist they cannot be much, if any, brighter than the parts of 
the spectrum where they occur. The observation of its 
spectrum is now very difficult.” 
In the scale of magnitudes I have employed, the light- 
ratio is 2-512 ; but the expression in magnitudes of the 
brightness of a variable star gives a very imperfect idea of 
the nature and extent of its changes, and as any speculations 
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 calculated the 
relative intensities of the light of T Coronse for every night 
of observation, taking the intensity of the light of a 10th 
magnitude star as unity. The results are given in the 
following table : 
