390 
MESSRS. W. E. AYRTON AND H. KILGOUR ON THE 
Table IX.— continued. 
Diameter, 4 mils, or 0T02 millim. Length, 27'69 centims. Water-jacket 13° C. 
April 14th, 1888. Fig. 12. (Plate 14.) 
Current, 
in amperes. 
P.D., 
in volts. 
Resistance, 
in ohms. 
Equivalent 
temperature of 
wire. 
Emissivity. 
0-04102 
0-30934 
7-540 
° C. 
17-9 
•000701 
0-06154 
0-46555 
7-565 
20-4 
•001047 
0-08205 
0-61868 
7-540 
17-9 
•002803 
0-10256 
0-77591 
7-565 
20-4 
•002909 
0-12307 
0-93418 
7-590 
23-0 
•003110 
0-14358 
1-0894 
7-587 
22-4 
•004502 
0-17435 
1-3319 
7-639 
27-8 
•004245 
0-20512 
1-5600 
7-605 
24-4 
•007593 
0-24614 
1-8951 
7-699 
33-8 
•006067 
0-28717 
2-2301 
7-766 
40-9 
•006210 
0-32819 
2-5877 
7-884 
52-4 
•005831 
0-36922 
2-9464 
7-980 
61-9 
•006006 
0-41024 
3-3246 
8-104 
74-6 
•005980 
0-46152 
3-8179 
8-272 
91-9 
•006034 
0-5128 
4-347 
8-477 
113-3 
•006000 
0-5641 
4-892 
8-655 
132-0 
•006258 
0-6154 
5-498 
8-935 
162-6 
•006010 
0'6666 
6-141 
9-211 
193-0 
•006132 
0-7179 
6-809 
9-483 
222-7 
•006282 
0-8205 
8-340 
10-164 
298-9 
•006441 
We have already drawn attention to the fact that the above wire, of 4 mils or 
0T02 millim. in diameter, has a much smaller • variation of resistance with tempe¬ 
rature than the other wires, and therefore that it is probable that this wire has some 
iridium or silver in its composition. From the preceding table we see that the 
variation of emissivity with temperature is also much smaller with this wire than 
with the others. 
