DR. JOULE ON SOME THERMO-DTNAMIC PROPERTIES OE SOLIDS. 
]07 
Weight laid on 
in pounds. 
t 
j' 
p - 
e, or mean 
expansion 
by heat be- 
tween per- 
manent and 
temporary 
tension. 
1 
5 
1 
— ) 
W 
or recipro- 
cal of mean 
weight per 
Theoretical 
result, or 
product of 
the pre- 
ceding five 
Experi- 
mental re- 
sult taken 
from the 
foregoing 
Experi- 
mental re- 
sult cor- 
rected for 
elongation 
of rubber 
Permanent. 
Temporary. 
foot. 
columns. 
Table. 
by use. 
0 
7 
281 
1390 
-7 
+ -i- 
9009 
1 
•Us 
1 
■1917 
-6"002 
-0-004 
-6-004 
7 
14 
281 
1390 
-7 
1 
5003 
1 
•415 
1 
•1759 
+ 0-004 
+ 0-003 
+ 0-003 
14 
21 
281 
1390 
-7 
2435 
I 
•415 
1 
•1576 
+ 0-009 
+ 0-015 
+ 0-016 
21 
28 
281 
1390 
-7 
1 
1360 
•415 
1 
•1383 
+ 0-018 
+ 0-039 
+ 0-043 
28 
35 
281 
Tw 
-7 
1 
814 
1 
■415 
1 
•1194 
+ 0-035 
+ 0-042 
+ 0-047 
35 
42 
281 
1390 
-7 
1 
656 
1 
•415 
‘1031 
+ 0-050 
+ 0-042 
+ 0-050 
0 
42 
+ 0-114 
+ 0-137 
+ 0-155 
53. In the last two columns of the above Table are recorded the actual quantities of 
heat observed in the experiments given in (46), and the same corrected on account of 
the thong not having then been so much stretched by use. I am of opinion, however, 
that this circumstance would not cause any material difference in the thermal effect of a 
given strain, and that therefore the last column but one is the proper one to compare 
with theory, which it will be found to do quite as well as could have been expected. 
54. After the experiment on the contraction by heat of the thong when it was 
stretched by 42 lbs., I removed all the weights except 2 lbs., and then a day or two 
afterwards observed as follows : — 
Temperature 
Temperature 
Contraction per 
Contraction per 
successively 
Length. 
successively 
Length. 
degree of tem- 
degree of tem- 
raised. 
lowered. 
perature raised. 
perature lowered. 
0 
-0-4 
4-445 
3°-2 
4-236 
25 
4-339 
26 
4-251 
! 
12 12 
¥2Vo 
50 
4-26 
50 
4-26 
55. It will be observed that the effect of a rise of temperature in the above experi- 
ment was to take out the set which had been given to the thong by previous experiments 
at higher tension. Afterwards, the effect of cooling, as shown in column 4, is a con- 
traction so great, as to prove that the set continued to be taken out after the heat whicli 
commenced its removal was withdrawn. That this was the case was proved by repeat- 
ing the experiment several times, using the same weak tension of 2 lbs. ; when the 
lengths at 8°’ 8 and 52°' 8 were found to be 4'241 and 4’254 respectively, indicating an 
expansion of only degree. 
56. On removing all tensile force, and applying a moderate warmth, the thong 
