AND STRAIN ON THE ACTION OE PHYSICAL FORCES. 
131 
Experiment L VI. 
The same iron wire as had been used for Experiment LV. was loaded for some time 
with 8 kilogs. ; 4 kilogs. were then removed and the wire allowed to rest for 24 hours, 
when the effect on the length of the wire produced by putting on and taking off 
2 kilogs. was found to amount to an alteration of ‘940 half-millim. at 100° C. After 
the action of the steam had been stopped for two hours and the temperature was about 
20° C., the alteration produced by the same load amounted to '985 half-millim., and 
after 20 hours rest at the temperature of 13° C. was found to be '945 half-millim. 
The wire v r as now tested with 4 kilogs., when the alteration of length produced by this 
new load was 1'910 half-millim. at 13° C., and after heating for some hours to 100° C., 
1'911 half-millim. The source of heat having been removed and the wire allowed to 
cool slowly for 20 hours, the alteration caused by the same load was 1*880 half-millim. 
at 13° C. 
Experiment LVII. 
An annealed nickel wire, '09213 centim. in diameter, was loaded for several hours 
with a weight of 18 kilogs.; 10 kilogs. were then permanently left on the wire for 
24 hours, and the alteration of length effected by a load of 8 kilogs. at a temperature 
of 16° C. amounted to 1'250 half-millim. The wire w 7 as heated to 100° C., and the 
alteration was now found to amount to 1'360 half-millim. After cooling down for 
the next five hours to a temperature of about 20° C. the alteration became 1'350 half- 
millim., and after three days at a temperature of 15° C. proved to be 1'250 half- 
millim. 
Experiment L VIII. 
The same copper wire as had been used in Experiment XLIX. was loaded for some 
hours with a weight of 11 kilogs.; 7 kilogs. were then allowed to remain on permanently 
and the wire suffered to rest for two days. It was then raised to the temperature of 
100° C. with the weight of 11 kilogs. on, and cooled again to the temperature of the 
room. These operations w ? ere repeated each four times during a space of four days, 
and on the last of these the alteration of length produced by a load of 4 kilogs. was 
found to be 1*37 4 half-millim. at 100° C. ; on cooling to 15° C. the alteration caused 
by the same load proved to be 1*310 half-millim., and this, or nearly the same 
alteration, had been found to be produced by the load at the temperature of the room, 
which temperature varied from 15° C. to 16° C. on each of the previous days. 
The following table exhibits the difference of the alteration of electrical resistance 
and of length at the temperature of the room and at 100° C. 
s 2 
