AND STRAIN ON THE ACTION OF PHYSICAL FORCES. 
91 
Experiment XXVII. 
The same wire as in the last experiment was allowed to run down for a few minutes 
longer, and then the following observations were made :— 
Increase of resistance 
in divisions of 
the platino-iridium wire. 
Time in minutes. 
Ratios of consecutive 
times. 
1st 
. . 40 
13-0 
2nd 
. . 40 
19-0 
1-462 
3rd 
. . 40 
24-0 
1-262 
4tli 
. . 40 
30-0 
1-250 
5th 
. . 40 
41-8 
1-394 
11th 
.. . 83-40 
415 
Mean value of ratios = 1"342. 
It is to be noticed that here the increase of resistance takes place more regularly; 
and though the ratios of consecutive times are not very constant, it would seem that 
the times form a geometrical progression, since the time for the last increase of 
resistance, as calculated from the formula £=13 X l'342 n ' 83 , where t denotes the time, 
is 422 minutes—a number agreeing sufficiently well with the observed time. 
The wire was afterwards loaded more and more, and the values of the ratios of 
consecutive times, as determined in the same manner as in the last experiment, are 
recorded in Table XII. 
Table XII. 
Resistance 
of the 
wire in 
terms of 
the 
comparison' 
wire. 
1-056 
1-080 
1120 
1177 
Total load 
on the 
wire in 
measures 
of water, 
each 
measure = 
5-825 
kilogs. 
9 10 
9-75 
10- 75 
11- 75 
Calculated 
load in 
kilogs. 
per square 
centim. 
1448 
1570 
1759 
1971 
Percentage 
value 
of the 
increments 
of 
resistances 
repre¬ 
sented by 
40 divisions 
of the 
platino- 
iridium 
■0314 
•0311 
•0305 
•0298 
Ratios of the consecutive times 
required by the loads 
to produce equal increments of resistance. 
1-24, 2-00 
1 33 1-38 
1-10 1-21 
1-21 
1-32 
1-07 
112 115 1-13 
1-33 
1-35 
1-23 
1-16 
1-29 
1-08 
114 
1-08 
117 
1-21 
1-17 
1-12 
1 33 
118 
114 
1-50 
1-30 
1-25 
1 27 1-24 1 22 
1*20 1-24 
1-18 M3 1-25 
Mean 
values 
of 
ratios. 
1-35 
1-26 
117 
113 
Mean 
values of 
ratios 
calculated 
for a 
percentage 
increment 
of 
resi stance 
= 1 . 
2-572 
2-097 
1-721 
1-492 
