174 
CAPTAIN ABNEY ON THE SENSITIVENESS 
Table X. 
Scale number, 27’3. Scale number, o2'8. 
Sector 
Equivalent 
Readings of apertures. 
Readings of apertures. 
in 
values 
degrees. 
of annulus. 
Logs. 
Lo 
0'< 
S. 
I 
S. 
L. 
\j. 
S. 
L. 
S. 
L. 
180 
0 
90 
35 
90 
12b 
3-23 
2-92 
ibo 
135 
3-14 
2-84 
45 
70 
140 
210 
2-80 
2-19 
185 
255 
3-42 
1-80 
22-5 
105 
200 
305 
2-28 
1-38 
270 
380 
1-68 
*73 
11-25 
140 
230 
370 
2-02 
•82 
305 
445 
1-38 
■17 
5-6 
175 
295 
470 
1-46 
- -04 
310 
520 
1-33 
- -47 
Extinction 
200 
325 
525 
1-21 
- -51 
340 
540 
1-08 
- -64 
Sector 
in 
degrees. 
Equivalent 
values 
of annulus. 
Scale number, 44. 
Scale number, 50-6. 
Readings o 
: apertures. 
Readings of apertures. 
S. 
L. 
Lo 
gs. 
s. 
L. 
Logs. 
S. 
L. 
S. 
li. 
180 
0 
0 
0 
4 
4 
40 
40 
3-66 
3-66 
90 
35 
40 
75 
3-66 
3-35 
110 
145 
3-05 
2-75 
45 
70 
110 
180 
3-05 
2-45 
170 
240 
2-54 
1-94 
22-5 
105 
200 
305 
2-28 
1-38 
240 
345 
1-94 
1-03 
11-25 
140 
260 
400 
1-76 
•56 
300 
440 
1-42 
•22 
5-6 
175 
310 
485 
1-33 
- -17 
330 
505 
1-16 
- -34 
Extinction 
200 
350 
550 
•99 
- -73 
340 
540 
1-08 
- -64 
N.B.—S. and L. refer to the small and large aperture respectively. From fig. 5 it 
is found that the extinction value of the larger aperture, *94 diameter, requires 200° 
more of the annulus to extinguish it than the smaller aperture '086 diameter. This 
accounts for the last line in the table. 
Fig. 7 shows the logarithm of the readings of S. N. 27'3 in the blue and S. N. 50’6 
in the orange (D.). The other series of readings are so close to the above that they 
are omitted. 
