METAL SURFACES AND LIQUIDS IN CONTACT WITH THEM. 
79 
III. —Effect of Varying Ranges of Teuij^erature v and r remaining constant. 
As an example, the following set of results may be quoted :—- 
Diameter of 
pipes. 
T 
-^0 
h- 
q. 
V. 
Rise of 
temperature. 
1-.S9 
47-55 
18-00 
•23-92 
186-0 
5“-92 
1-39 
39-35 
18-01 
22-22 
186-0 
4°-21 
T39 
32-45 
18-05 
20-83 
186-0 
2^-78 
Now if the heat transmitted under these conditions varied simply in the range 
of temperature, we should have had for the whole surface of the pipe 
C (Tq — t) ds — Wdt, 
or, 
CiS = W log , 
J-O 4 
where 
S = whole surface of the pipe, 
= a constant, 
W = weight of water llowiug through the pipe jier second. 
T — ^ 
Now the values of log -for the experiments quoted are ‘222, •218, •213 
- Lq ^-2 
respectively, which show that the heat transmitted is proportional to (Tq t) 
multiplied by a function of the temperature Tq. 
IV. —Effect of Varying the Initial Temperature q, the range (Tq — q) v and r 
being constant. 
A set of experiments at G9 ’0 centims. per second gave :— 
Diameter of 
pipes. 
To- 
ty. 
q. 
V. 
Rise of tem¬ 
perature. 
1-.39 
1-39 
35-00 
53-60 
18-80 
37-40 
22-18 
41-25 
69-0 
69-0 
3°-38 
3°-85 
These results show a considerable increase in the heat transmitted for the same 
range and velocity; this increase, as will be seen by com.paring Experiments III. and 
