171 
A fourth experiment gave the following results — 
WiF'-® = W2F-2 
Here h + = 28*4 and h + = 27*4. 
A fifth experiment gave 
WiF3-'^ = W2F'®^ 
Here we have tx + = 31 ’95 and tx + ^2 = 30 '35. 
It seems to me that the above results are as favourable 
as might be expected considering the difficulties of the 
enquiry ; and even if all external circumstances necessary 
for the successful completion of such experiments had 
existed, there would yet remain the difficulty of deciding 
about the equality of two grey tints. In such matters it 
is difiicult to say where judgment ends and fancy begins. 
That any discrepancies might be due to such a cause was 
shown by the following experiments : — I took the two 
cylinders and poured from one into the other with the 
intention of obtaining the same tint in both. In one trial 
I could not very clearly distinguish a column 16*4c. long 
from one 14'6c. long, and in a second trial a column 16 '20. 
long seemed to give the same tint as a column 14'6c. long. 
In the above experiments I used one eye only, namely, the 
right one, 
I also made the following experiments : — I took as the 
standard of intensity W seen through a column 12*5c. long. 
On a former occasion I had made 6*2 as the equivalent 
column to be used with W 2 . On the present occasion I 
thought 6 '5c. gave a nearer result, so I took the column at 
this length. Now if the law of absorption of light be true, 
if we increase both columns by the same quantity, the 
intensities should again correspond. So I added 4c. to each, 
making one column 16’5 and the other 10*2. I thought 
that the tints were the same. I now made one column 
20' 5 and the other 14‘2. Again I thought the tints were 
the same. Finally I made one column 24'5 and the other 
18*2. The tints seemed again to correspond. 
“Note on Three New Stars,” by Joseph Baxendell, 
F.RA.S. 
