babuh.] CALIBRATION OF ELECTRICAL PYROMETERS. 113 
Table 16.— Calibration of tliermo-couples Nos. 17, 18, 22, 35, 36.— Continued. 
No. 
t. 
T. 
e ab- 
served. 
e calcu- 
lated. 
Se. 
0jo— e. 
e2o. 
a and b. 
Time. 
36 
°a 
20.7 
21.2 
21.7 
22.3 
°a 
930 
930 
930 
930 
Micro- 
volts. 
10214 
10205 
10193 
10245 
Micro- 
volts. 
Micro- 
volts. 
Micro- 
volts. 
Micro, 
volts. 
10216 
10210 
10202 
10259 
Microvolts. 
7.785 
0. 003913 
h. in. 
2 55 
3 28 
Mean 
52 
4 33 
21.5 
930 
10212 
10467 
-255 
8 
10220 
36 
20.8 
21.8 
22.4 
448 
448 
448 
4309 
4308 
4293 
(4329) 
(-26) 
4311 
4318 
4308 
(7. 19) 
(0. 00629) 
11 49 
Mean 
12 19 
45 
21.7 
448 . 
4303 
4108 
+195 
9 
4312 
% 
20.8 
21.1 
357 
357 
3217 
3221 
(3214) 
(+5) 
3219 
3226 
3 00 
Mean 
4 50 
21.4 
19. 0~ 
19.4 
18.6 
18.8 
357 
186.5 
186.8 
186.4 
3219 
3121 
+98 
(+13) 
-5 
7 
3226 
1435 
1431 
1426 
1416 
?fi 
1443 
1436 
1437 
1425 
(1422) 
10 31 
Mean 
11 10 
2 10 
19.0 
186.6 
1435 
1440 
-9 
1426 
3P 
19.1 
18.6 
99.9 
99.9 
631.2 
636. 1 
(643) 
(—10) 
624.3 
625. 2 
12 
Mean 
12 48 
18.8 
99.9 
633.6 
669 
-35 
-9.3 
624.3 
From the constants contained in these tables I have calculated the 
values of e 2 o when the difference of temperature varies between T— 20= 
100°, and T— 20=1,500°, for the reason that I shall make use of these 
values below. In general there are three sets of values of e 20 available ; 
the fipst of these is calculated with the constants, including the zinc 
calibration; the second with the constants applying only as far as the 
sulphur calibration contained in this chapter; and the third with the 
constants applying as far as the mercury calibration contained in Chap- 
ter I. The last two sets having been made respectively in Washington 
and in New Haven will be so designated. To these couples are added 
results for Nos. 19 and 20, both of which are 5 per cent. Pt-Ir alloys. 
They will be referred to elsewhere. 
Bull. 54 8 
(767) 
