DR. J. P. JOULE ON A NEW DETERMINATION 
!76 
Table I., Part 2. — Experiments with Friction of Water and Brass. Weight, W, lifted 
in the first fifteen, 146 19 '5 grains ; in the last two, I 8 1 2 2 ’9 grains. Average pro- 
portion of metallic to total friction, yy, Time occupied by each of the first fifteen, 
50 m ; by the last two, 41 m and 41 m 30 s . Value, or V, of one division of the 
thermometer, 0 o, 077214. Circumference of groove of calorimeter, P, 2 ‘77386 feet. 
No. 
Number of 
revolutions. 
11. 
Capacity 
of the 
calorimeter. 
C. 
Mean 
temperature 
of the 
calorimeter. 
Mean 
temperature 
of the 
atmosphere. 
Difference. 
Else of 
temperature 
of 
calorimeter. 
Ditto, 
corrected 
for 
radiation, Ac. 
T. 
Mechanical 
equivalent 
or 
E W P 
C T V 
1 
5545 -0 
84359 -5 
414 -480 
400 190 
14 290- 
42-761 
44-478 
776-15 
2 
5378 0 
84413 4 
412 -570 
399 130 
13 -440- 
41 -830 
43 -482 
769 -52 
3 
5522 6 
84369 -5 
415-594 
416 030 
0 "436 + 
44 '606 
44 -585 
771 06 
4 
5685 '2 
84309 1 
418 020 
402 390 
1 5 '630 — 
43 -905 
4 7 -646 
775-89 
5 
5321 3 
84-139 5 
423-522 
409 792 
13-730- 
41 347 
43 -071 
768-43 
6 
5756 -5 
84429 4 
349 325 
335 160 
14-165- 
44 890 
46 -506 
769 -98 
5753 -5 
84424 1 
349 -502 
332 934 
16 568- 
44 '509 
46 -251 
773-87 
8 
5740-7 
84429-1 
363 325 
351 5S5 
1 1 -740- 
44 923 
46 -137 
774 01 
9 
5714-0 
84448 -6 
366 028 
338 -175 
27 853- 
42 682 
45 -703 
777 -55 
10 
5725 -7 
84415 0 
352 -730 
351 -466 
1 264- 
46 088 
46 167 
771 -60 
11 
5695-0 
84383 1 
360 -146 
366 -080 
5 934 + 
46 631 
45 -706 
775-51 
12 
5702 2 
84370 1 
351 -998 
349 -282 
2-716- 
45 -878 
46 003 
771 59 
13 
5b81 2 
84355 0 
335 -844 
322 -280 
13-564- 
44 295 
45-827 
771 80 
14 
5702 -3 
84353 -0 
326 -922 
325 294 
1 fL8- 
45 883 
45 -891 
773 64 
15 
5670 -8 
84291 -0 
352 -669 
348 867 
3 -802- 
45 368 
45 -829 
770 -97 
16 
4965 -5 
842S2 -1 
324-334 
316 -810 
7 -524- 
48 -750 
49 -630 
772-85 
17 
4953-3 
84398 0 
307-643 
298 -298 
9-345- 
48 535 
49-503 
771 -87 
Average 
- - • •{ 
366-16 
or 58° -46 
} - 
•• 
772-72 
The mean temperature of the atmosphere was derived from observations taken from 
minute to minute, but there were only two readings of the temperature of the calori- 
meter, viz., at the commencement and termination of an experiment, from which to 
determine its average temperature. Suppose a b, fig. 7, to represent the line of air 
temperatures during an experiment lasting 41 m : the temperatures of the calorimeter 
will be represented by a line similar to c d ef The wheel was set in motion 2 m after 
the first reading was taken. The temperature then rose until, at 35 m , the wheel was 
stopped. The temperature then declined slightly, until, at 41 m , the last reading was 
taken. The fine is slightly curved ; a few seconds are occupied in starting and stopping 
the wheel, and the thermometer reads a little backwards. Ta kin g all these circum- 
stances into account, I found that the average temperature for the whole time was 
c + f 
very accurately represented by 37 .g- + 4/. The mean temperature of the calorimeter 
41 
for other times of experiment was estimated in a similar manner. 
To obtain the corrected rise of temperature in the last column but one, the 
correction to the air temperature indicated in the first part of the Table was 
supplied. For instance, in the first experiment the temperature of the air was 
