240 Capt, Kater’s Appendix to further Experiments 
stance by diverting the attention from the white circles might 
occasion an inaccurate decision, I prepared two white disks of 
card paper half an inch in diameter, which were supported on 
black wires, and these I found far preferable to every other 
contrivance which I employed. Care was taken to place the 
disks as near the axis of the mirror as was possible without 
their interfering with each other. 
The following were the results. 
With disks of card paper supported on wires. 
Distance of the candle from the mirror 186 inches. 
Observers 
Distance 
equal 
of the disk 
y illumina 
s when 
ted. 
Distance 
of the disk 
from the 
focus 
without. 
Distance 
of the disk 
from the 
focus 
within. 
Ratio of th 
sity of the 
equal disn 
the focus. 
e inten- 
hgh at 
inces from 
1st reading. 
2 d reading. 
Mean. 
Within. 
Without. 
w 
K 
Mvself 
K 
W 
Myseli 
23^90 
24,80 
2340 
23>7 o 
23,82 
24n95 
24>^.5 
23,00 
24.95 
2435 
24,60 
23.01 
24.37 
24,90 
24,17 
24.02 
24,21 
9.8 
9.8 
9.8 
9.8 
9.8 
9.8 
13.21 
14.57 
13,10 
14.37 
14.22 
14.41 
1000 
ICOO 
1000 
1000 
1000 
1000 
415 
453 
421 
4% 
475 
4<.'3 
Mean 
1000 
448.5 
