IO 
RESEARCHES IN STECEAR PHOTOMETRY. 
evidence in Table 3 maybe summed upas follows: (1) The results by two inde¬ 
pendent methods, standard stars and laboratory measures, are in good agreement 
the average probable error of the points platted on curve A 12 being less than 
±0.03, with a maximum of ±0.07. (2) The laboratory measures were all made 
by matching artificial stars which closely resembled the real stars. 
Table 3. — Absorption of Wedges II and V. 
Wedge V. 
Wedge II. 
Scale. 
12-inch. 
6-inch. 
11 c. 
Pleiades. 
Zollner. 
Wheel. 
A 12. 
E 6. 
60 
(5-80) 
(5 • 49 ) 
55 
5-34 
5- 12 
.... 
5.22 
.... 
5-32 
50 
485 
4.76 
.... 
4.80 
4.70 
4-99 
45 
4-39 
4.28 
4.28 
4-33 
4.41 
4 - 5 i 
40 
3.80 
3-77 
3-77 
3-78 
3-85 
3-93 
35 
3 - 14 
3-2 7 
3.20 
3 i 9 
3 • 3 ° 
3-35 
30 
2.60 
2.74 
2.61 
2.65 
2.68 
2.85 
25 
215 
2.27 
(2.18) 
2.20 
2. 13 
2.27 
20 
1.65 
1.80 
(i- 74 ) 
1.72 
i -59 
i- 5 i 
15 
1.07 
1.08 
1.07 
1.06 
0-93 
0.72 
10 
0.46 
0.42 
0.50 
0-43 
0.28 
0. 11 
5 
.... 
0.06 
.... 
0.05 
(0.00) 
.... 
0 
0.02 
.... 
(0.01) 
.... 
.... 
A check on the mean value of the absorption is furnished by the measured 
magnitudes of the stars near the limit of vision of the 6-inch telescope. Table 
4 gives the field, the estimate of the limit of vision, the photometric magnitude 
of the limit, the correction for atmospheric extinction, and the final corrected 
magnitude of the limit, expressed in both the Harvard and Potsdam systems. 
Table 4. 
Field. 
- Limit. 
Mag. 
Corr. 
Corr. Mag. 
H. 
P. 
H. 
P. 
Z Cassiopeiae. 
W Lyrae . 
S Eyrie. 
SX Cygni. 
RU Herculis. 
V Cassiopeiae. 
Mean. 
k 
2-3 <1 
z 
3 < n 
2<n 
q 
12.99 
12.60 
12.82 
12.34 
1305 
12.61 
12.88 
12.93 
13.24 
12.69 
1332 
12.94 
0.04 
0.00 
0.00 
0.00 
0.02 
0.03 
13 03 
12.60 
12.82 
12.34 
13 07 
12.64 
' 12.75 
12.92 
12.93 
13 24 
12.69 
13 34 
12.97 
13.01 
