58G 
MR. R. W. STEWART ON THE ABSOLUTE THERMAL 
reduction of about 2 per cent.), due to the fact that, in the case of the short bar used 
in determining the rates of cooling, the cooling surface includes the terminal faces of 
the bar. 
Table C. 4.—Table showing the values of Jx, the absolute thermal conductivity of 
Copper, at temperatures between 40° C. and 200° C. 
I. 
T. 
X. 
dOjclx 
(per centim.). 
2 
(per minute). 
e. 
M. 
k 
(C.G.S. units). 
°C. 
centims. 
°C. 
40 
68 
2-70 
192-50 
28 
0-816 
[-956] 
60 
46-2 
5-20 
369-74 
39 
•821 
[-973] 
80 
33-1 
7'65 
558-66 
60 
•828 
1-007 : 
100 
23-5 
10-55 
758-50 
59 
•833 
•999 
120 
16-5 
13-60 
950-70 
71 
•840 
•979 ■ 
140 
11-0 
16-80 
1142-60 
84 
•846 
•958 : 
160 
6-4 
20-20 
1334-50 
93 
•851 
•937 i 
180 
2-5 
23-90 
1623-70 
103 
•856 
•909 1 
II. 
T. 
dOjdx 
(per centim.). 
S [/() (deldt)] 
(per minute). 
0 . 
M. 
k 
(C.G.S. units). 
°C. 
centims. 
°C. 
40 
75-50 
2-40 
191.5 
29 
0-816 
1-085 
60 
51-65 
5-00 
375-2 
40 
•822 
[1-027] 
80 
38-10 
7-60 
561-9 
49 
•826 
[1-018] 
100 
28-60 
10-30 
753-6 
60 
•833 
1-015 
120 
21-45 
13-25 
945-8 
69 
•838 
•995 
140 
15-65 
16-50 
1145-7 
80 
•844 
•976 
160 
11-00 
19-93 
1339-1 
89 
•850 
•953 
180 
7-00 
23-53 
1532-3 
100 
•854 
•927 
200 
3-70 
27-20 
1714-5 
109 
•860 
•903 
Note 1.—On comparing the results here tabulated, it will be noticed that the data 
of columns 3 and 4 are very similar in I. and II. ; but reference to column 2 shows 
that the data of column 4 extend over a different length of the bar in the two cases. 
Note 2.—In I. we find the same falling-olf in the value of Jc at temperatures below 
j 00° C. as occurs in the case of the iron bar. 
Reducing the results given in these tables by the method of least squares, and 
assuming that the conductivity at t° C. is given by 
ki = a — ht, 
we have 
