PROFESSOR OSBORNE REYNOLDS ON ROLLING-FRICTION. 
169 
have been slightly to diminish friction, not only when starting from rest, but when 
rolling back, which confirms me in the opinion that the contrary result with oil was 
due to its obstructive action. 
India-rubber was then tried. A plate of this substance three eighths of an inch thick 
was glued to a piece of wood to prevent it working forward. The results are shown in 
Table III. The friction was very much greater than in the previous experiments, and 
the advantage lies with the clean surface. 
Table III. — Cast-iron Roller on India-rubber. 
Clean. 
Blackleaded. 
Headings. 
Headings. 
Difference. 
Difference. 
To. 
From. 
To. • 
From. 
-22-0 
+ 14-0 
36 
-24 
+ 18 
42 
O 
-28-0 
+ 15 
43 
-19 
+ 15 
34 
-12-0 
+ 18 
30 
-18 
+ 19 
37 
a 
p 
-19-0 
+ 15 
34 
-23 
+ 17 
40 
-16-0 
+ 16 
32 
— 22 
+ 17 
39 
■§ 
-18-0 
+ 15 
33 
-23 
+ 14 
37 
m 
— 25-0 
+ 12 
37 
-25 
+ 17 
42 
-23-0 
+ 15 
38 
-24 
+ 15 
39 
Mean 
.. 35-3 
Mean 
.. 38-75 
— 2 
+ 28 
30 
0 
+ 26 
26 
— 5 
+26 
31 
— 2 
+22 
24 
: m 
-6 
+ 27 
33 
- 1 
+25 
26 
' g 
-4 
+ 28 
32 
2 
+22 
24 
'r-3 d 
.2 
-3 
+ 30 
33 
-10 
+22 
32 
M O 
-4 
+ 30 
34 
-14 
+ 19 
33 
1 a 
-6 
+ 24 
30 
— 6 
+ 24 
30 
rO 
- 7 1 
+ 25 
32 
- 6 
+23 
29 
Mean 
.. 31-8 
Mean 
.. 28 
These results leave no doubt that rolling-friction does not depend greatly on the 
coefficient of sliding-friction between the roller and the surface. They are, however, 
completely in accordance with the explanation previously given of the manner in which 
sliding-friction acts to prevent the deformation of the surfaces at the point of contact. 
The Tendency to Oscillate. 
Another circumstance which was observed while making these experiments also offers 
strong evidence of this deformation, namely the tendency which the roller has to oscillate. 
This was always exhibited whenever the roller was slightly disturbed from rest on the 
level plane, and it was certainly not due to the fact of its having settled into a hollow ; 
for when on india-rubber it would make several considerable oscillations in whatever 
