606 PROFESSOR MACGREGOR AND DR KNOTT ON 
Table VI. contains the results of observations on the alloy, 10 per cent. of 
which by mass or about 10°92 per cent. by volume is iridium. 
TABLE VI. 
Resistance. 
Temperature. 
Observed. Calculated. 
1675+ C. 2147 2°7429 
36:0 2°806 2°8036 
57:8 2°875 2°8720 
73:0 2°918 2:9196 
95:3 2987 2:9890 
112:0 3:040 3:0398 
aly 3°080 30801 
142°8 3°135 3'1360 
1556 eel Ly 5) 31746 
The following formula represents the above results. 
R=2'69 + :003165¢— -0000002927?, 
whence r=1+:0011766¢—-000000108552’, 
and k=1—°0011766¢+ :00000149292’. 
Table VII. contains the measurements made with the alloy containing 15 
per cent. by mass or about 16°29 per cent. by volume of iridium. 
TABLE VII. 
Resistance. 
Temperature. 
Observed. Calculated. 
24:8° C. 20°175 20:1651 
50:6 20:560 20°5649 
70:1 20:855 20°8657 
85:2 21:103 21:0984 
102:0 21-360 2ie357 1 
118°0 21:°594 21:6032 
127:0 PAST 32 21°7416 
140°6 21:950 21:9505 
1549 22:170 22°1700 
The formula for this wire is : 
R=19°7817 + °015475¢— 0000004177’, 
whence r=1+'00078229¢— -0000000210632?, 
and k=1—:00078229¢ + :000000633052?. 
