MEASUREMENT OF TEMPERATURE. 
193 
Note : Observation IT. 1 is marked doubtful in mv book of notes, as there was a 
small glycerine bubble in the air tube connecting the mercury manometer with the 
sulphuric acid gauge ; moreover, it disagrees with observations taken a few minutes 
after with the same instrument, when the bubble had been dislodged (see II. 4, 5, &c., 
next Table). [Nevertheless, as the temperature was steady, it is not liable to the 
constant error (see p. 187, end).] 
Observations with Temperature varying. 
Table VI.—Thermometer No. 2. 
No. of ob¬ 
servation. 
Temperature 
Centigrade. 
Resistance 
observed. 
Resistance calculated by 
empirical formulae 
Resistance calcu¬ 
lated by 
exponential 
formula (e). 
Difference. 
(a) 
(b, 
23 
207-2 
1-7172 
1-717 
1-712 
1-7145 
-•0027 
22 
210-1 
1-7270 
1-727 
1-722 
1-7242 
-•0028 
21 
215-7 
1-7467 
1-746 
1-740 
1-7430 
-•0037 
20 
233-8 
1-8057 
1-809 
1-801 
1-8042 
— •0015 
19 
236-6 
1-8156 
1-819 
1-810 
1-8135 
-•0021 
18 
239-4 
1-8254 
1-828 
1-819 
1-8224 
-•0030 
17 
257-7 
1-8842 
1-891 
1-881 
1 -8834 
-•0008 
16 
263-4 
1-9038 
1-911 
1-900 
1-9028 
-•0010 
15 
278-2 
1-9530 
1-963 
1-948 
1 9515 
-•0005 
14 
281-5 
1-9629 
1-959 
1-9625 
-•0004 
13 
293-6 
2-0020 
1-999 
2-0020 
+ •0000 
12 
299-6 
2-0217 
2-018 
2-0213 
-•0004 
11 
317-8 
2-0806 
2-078 
2-0807 
+ •0001 
10 
323-8 
2-1003 
2-097 
2-0998 
-•0005 
9 
3311 
2T239 
2-121 
2-1235 
—-0004 
8 
336-1 
2-1394 
2-137 
2T395 
+ -0001 
7 
339-1 
2-1493 
2-147 
2 - 14b 2 
— ■0001 
6 
342-4 
2-1591 
2-157 
2-1595 
+ -0004 
5 
346-0 
2-1709 
2-169 
2-1711 
+ -0002 
4 
348-6 
2-1788 
2-177 
2T793 
+ ‘0005 
__1 
The above are all single observations, yet they are remarkably consistent with each 
other, and give a very smooth curve. They are given to show the capabilities of the 
method, and the great sensitiveness of a fine platinum spiral, 
Empirical Formulae. 
It is usual to apply the method of least squares to calculate the empirical formula 
which best suits the observations. This has the advantage of giving a great 
appearance of accuracy and completeness. In the present case, however, the gain, if 
any, would not compensate the trouble, and the simpler method of calculating from 
selected numbers gives equally good results. 
M DCCCLXXX VII.— A. 2 C 
