588 
MR. R. W. STEWART OR THE ABSOLUTE THERMAL 
For convenience of comparison these results are given below, followed by a Table 
showing previous results. 
Values obtained for Absolute Thermal Conductivities of Iron and Copper from. 
Experiments detailed in this Paper. 
[C.G.S. units.] 
Iron . . = 0-175 (1 --OOISO- 
Copper . = 1-12 (1 — *001^). 
Table showing the results of previous Determinations of the Absolute Thermal 
Conductivity of Iron and Copper. 
[C.G.S. units.] 
Iron. 
Copper. 
Authority. 
1 
0-209 (1--001470 
-164 
0-199 (1--0028740 
0-197 (1--000020 
0-17 (1--000020 
0-17 (1--0020 
1-108 
/ 1-027 (1--002140 1 
I -983 (1--001520 J 
f 1-08 (1 +-001301 
I -71 (1 +-00140 J 
0-72 (1 +-000040 
0-51 (1 +-00570 
Forbes 
N EUIIAXN 
o 
Angstrom 
Tait 
Lorenz 
Kirchhoff and Hansemann 
The Emissive Poivers of the Surfaces of the Iron and Copper Bars. 
From the data obtained in the cooling experiments involved in the conductivity 
research, it is evidently possible to calculate the emissivities of the surfaces of the 
bars at different temperatures. 
As it may be of interest to place these on record, they are given in the following 
table. 
The iron bar was a f-inch square bar, and its surface was blackened and lightly 
polished with blacklead. 
The copper bar was a round bar of -l-inch diameter, and its surface was smooth 
and polished. 
