MR. JOULE ON THE MECHANICAL EQUIVALENT OF HEAT. 
73 
during the remaining 50" (estimated from the rate of increase of temperature between 
the observations at 5' and 10') will be 0°'004. These corrections, applied to 70°’518, 
leave 70°'495 as the temperature of the apparatus at the moment of immersion. 
The temperature of the apparatus at 26' was 50°'778, indicating a loss of 19°'717- 
That of the water at the same time of observation, being corrected for the effect of 
the atmosphere (deduced from the observations of the cooling from 26' to 36' and of 
the heating from 0' to 10'), will be b(f'777i indicating a gain of 3°063. Twenty such 
results, obtained in exactly the same manner, are collected in the following Table. 
Table III. 
No. 
Corrected temperature 
of water. 
Gain of heat 
by the water. 
Corrected temperature 
of apparatus. 
Loss of heat by 
the apparatus. 
Commencement 
of experiment. 
Termination of 
experiment. 
Commencement 
of experiment. 
Termination 
of experiment. 
1 
47714 
50*777 
3*063 
70*495 
50*778 
19*717 
2 
48*127 
51*113 
2*986 
70*518 
51*147 
19*371 
3 
48*453 
51*430 
2*977 
70*642 
51*452 
19*190 
4 
47*543 
50*598 
3*055 
70*674 
50*684 
19*990 
5 
44*981 
48*449 
3*468 
70*901 
48*468 
22*433 
6 
45*289 
48*701 
3*412 
70*769 
48*657 
22*112 
7 
45*087 
48*497 
3*410 
70*504 
48*494 
22*010 
8 
46*375 
49*614 
3*239 
70*678 
49*662 
21*016 
9 
47*671 
50*832 
3*161 
71*500 
50*873 
20*627 
10 
47*693 
50*801 
3*108 
70*878 
50*821 
20*057 
11 
48*728 
51*714 
2*986 
70*947 
51*714 
19*233 
12 
47*240 
50*414 
3*174 
71*006 
50*392 
20*614* 
13 
48*324 
51*345 
3*021 
70*939 
51*362 
19*577 
14 
49*079 
51*905 
2*826 
70*332 
51*937 
18*395 
15 
49*635 
52*490 
2*855 
71*012 
52*504 
18*508 
16 
47*207 
50*282 
3*075 
70*265 
50*263 
20*002 
17 
46*227 
49*402 
3*175 
69*877 
49*314 
20*563 
18 
46*053 
49*296 
3*243 
70*367 
49*258 
21*109 
19 
45*733 
48*981 
3*248 
70*068 
49*001 
21*067 
20 
47*170 
50*317 
3*147 
70*741 
50*332 
20*409 
Mean... 
3*13145 
20*300 
I did not consider these experiments on the capacity of the apparatus sufficiently 
complete, until I had ascertained the heat produced by the wetting of the surface of 
the iron vessel. For this purpose the following trials were made in a similar manner 
to the above, with the exception that the observations did not require to be extended 
beyond 26'. 
MDCCCL. 
L 
