DEGREE OF CONSTANT TEMPERATURE. 
69 
Table 1. — List of thermo-couple; 
Tliermo-couple. 
No. 
a x 10 3 
b x 106 
Where made, etc. Calibration 
interval. 
+ 
- 

Ag 
Cu 
261 
174 
Laboratory ; 0° to 190°. 
1 
Ag, 5% Pt 
Cu 
5730 
7010 
Do. 
2 
Ag,10%Pt 
Cu 
7230 
10100 
Do. 
3 
Ag, 150/6 Pt 
Cu 
8964 
11830 
Do. 
4 
Ag, 25% Pt 
Cu 
9641 
15220 
Do. 
5 
Pt 
Cu 
4024 
11450 
Commercial ; 0° to 190°. 
6 
Pt soft 
Cu 
3222 
12740 
Paris ; 0° to 190°. 
7 
Pt hard 
Cu 
3760 
9680 
Do. 
8 
Pt Ir 5% 
Cu 
906 
9150 
Do. 
9 
Cu 
Pt, Ir 20% 
3364 
38D0 
Do. 
10 
Pd 
Cu 
8590 
21100 
Do. 
11 
ITi 
Cu 
20090 
22000 
Do. 
12 
Ni 
Pt soft 
17630 
4900 
Do. 
13 
Pd 
Pt hard 
5517 
8375 
Do. 
14 
Pt hard 
Pt, Ir 20% 
7197 
6325 
Do. 
15 
Pd 
Pt, Ir2o% 
12347 
16855 
Do. 
16 
Cu 
Pt hard 
Cu 
Pt,Ir20% 
Commercial ; 0° to 190°. 
Paris ; 0° to 450°. 
17 
7660 
3900 
18 
Pt hard 
Pt,Ir20% 
7640 
3670 
Do. 
19 
Pt hard 
Pt,Ir 5% 
3075 
—96 
Paris ; 0° to 370°. 
20 
Pt hard 
Pt.Ir 5% 
3056 
-91 
Do. 
21 
Pd 
Pt hard 
5253 
9700 
Do. 
22 
Pt hard 
Pt, Ir 20% 
7640 
3810 
Paris ; 0° to 450°. 
23 
Pt hard 
Pt, Ir 5% 
2972 
475 
Paris ; 0° to 370°. 
24 
Pt hard 
Pt, Ir 2% 
1883 
—1501 
Laboratory ; 0° to 370°. 
25 
Pt soft 
Pt, Pd 3% 
287 
1194 
Do. 
26 
Pt soft 
Pt, Pd 10% 
975 
2732 
Do. 
27 
Pt, Ir 5% 
Pt, Ir 10% 
2362 
1525 
Paris ; 0° to 370°. 
28 
Pt, Ir 5% 
Pt, Ir 15% 
3888 
2685 
Laboratory ; 0° to 370°. 
29 
Pt,Ir 5% 
Pt, Ir 20% 
4507 
3982 
Paris ; 0° to 370°. 
30 
Pt com. 
Pt, Ni 5% 
8428 
505 
Laboratory ; 0° to 370°. 
31 
• Pt com. 
Pt, Ni 2% 
4560 
48 
Do. 
32 
Ptcom. 
Pt, Ni 3% 
1978 
519 
Do. 
33 
Pt com. 
Pt,Ir5% 
3639 
1472 
Do. 
34 
Pt com. 
Pt, Ir 7% 
4704 
2073 
Do. 
35 
Pt soft 
Pt, Ir 20% 
7180 
6270 
Paris ; 0° to 450°. 
36 
Pt soft 
Pt, Ir 20% 
7190 
6290 
Do. 
37 
Pt soft 
Pt, Ir 20% 
(7200) 
(6300) 
Do. 
38 
Pt soft 
Pt,Ir20% 
(7200) 
(6300) 
Fused over from old elements. 
39 
Pt soft 
Pt, Ir 20% 
(7200) 
(6300) 
Do. 
40 
Pt soft 
Pt,Ir20% 
(7200) 
(6300) 
Do. 
Data for the mercury vapor baths. — Returning from this digression to 
the subject proper, we insert Table 2 to exhibit the degree of constant 
temperature arrived at in the mercury apparatus. The observations 
are made in time series. T is the temperature of the hot junction, 
placed at i in Fig. 3, and t the temperature of* the cold junction of the 
thermoelement No. 18, at the time specified in the same horizontal row. 
T is computed from the thermo-electric data. In the first part of the 
(723) 
