MEASUREMENT OF TEMPERATURE. 
227 
Table F.— I. —Comparison of Platinum (No. 1) and Commercial Iron Wire. 
(The observations in this Table are the same as those in Table XI., p. 206.) 
Resistances observed. 
Temperatures deduced. 
Difference 
observed, 
/«i - Ph 
Difference 
calculated 
by formula 
(fe - pt) 
Deviation 
from 
parabola, 
obs. — calc. 
Number 
of 
observation. 
Platinum. 
Iron. 
Ph 
t 
f e \ 
O 
O 
O 
O 
O 
O 
1 
1 
0 
0 
0 
0 
0 
0 
(1) 
1-1225 
1-1732 
35-41 
35-05 
32-8 
- 2-6 
- 3-5 
+ 0-9 
(2) 
1-3453 
1-5263 
99-79 
99-79 
99-79 
0 
0 
0 
(3) 
1-5990 
2-0036 
173-2 
175-2 
190-3 
+ 17-1 
+ 19-8 
- 2-7 
(4) 
1-9220 
2-7692 
266-5 
273-9 
335-4 
+ 68-9 
+ 71-5 
- 2-6 
(5) 
2-2283 
3-6715 
355-0 
370-7 
506-4 
+ 151-4 
+ 150-5 
+ 0-9 
(6) 
2-5548 
4-8396 
449‘4 
'477-9 
726-0 
+ 276-6 
+ 270-9 
+ 5-7 
(7) 
2-8840 
6-2667 
544-5 
590-1 
998-4 
+ 454-0 
+ 433-9 
+ 20-1 
(3) 
3-0314 
7-0566 
587-1 
641-8 
1148-2 
+ 561-1 
+ 521-6 
+ 39-5 
(9) 
The value of t is given by the formula 
t—pt = 1-57 {(t/ 100) 3 — (£/100)}.( d) 
The value of the difference is calculated from the formula 
fe — pt = 15-0{(tJ100f - (t/100)} . (fe) 
The temperature by iron wire is given by the formula 
fe = 100(Pv/Pv 0 - 1)/(K 1 /R 0 - 1), 
where B^/Hq = P5274. 
Table F.-ii.—C omparison of Platinum (No. 2) and Pure Iron Wire. 
Resistances observed. 
Temperatures deduced. 
Difference 
observed, 
P-2 ~ Vh 
Difference 
calculated 
by formula 
(fe - pt) 
Deviation 
from 
parabola, 
obs. — calc. 
Number 
of 
observation. 
Platinum. 
Iron. 
pt 2 
t 
/«2 
1-0610 
1-0863 
O 
18-15 
O 
17-92 
o 
16-48 
O 
- 1-67 
O 
- 2-2 
O 
+ 0-53 
(1) 
1-3360 
1-5238 
100 
100 
100 
0 
0 
0 
(2) 
1-9578 
2-9777 
290-4 
299-7 
377-6 
+ 87-2 
+ 89-7 
— 2*5 
(3) 
2-2088 
3-6914 
359-8 
376-1 
513-8 
+ 154-0 
+ 155-8 
-1-8 
(4) 
2-5102 
4-7820 
449'4 
477-9 
722-1 
+ 272-7 
+ 270-9 
+ 1-8 
(5) 
2-8578 
6-2825 
552-9 
600 1 
1008-5 
+ 455-6 
+ 450 1 
+ 5-5 
(6) 
The formulse are as before, but the values of 1:4/It 0 are different. (See Obs. (2).) The 
deviations are taken from the last column and set down on Plate 13, fig. 11 ; the abscissa 
is the approximate temperature by air thermometer ; the similarity of the curves shows 
that the resistance-variations of the wires are similar in character. 
Herein we see the treachery of the common empirical formula. Had we only the 
2 G 2 
