PROFESSOR OSBORNE REYNOLDS ON EOLLING-ERICTION. 
171 
Table V. — Cast-iron Roller on Cast Iron. 
Clean. 
!| 
Oiled. 
Readings. 
Readings. 
difference. 
! Difference. 
To. 
From. 
To. 
From. 
-6-5 
+ 0-3 
6-8 
-1-3 
4-4-0 
5-3 
to 
-2-8 
+2-4 
5-2 
-2-8 
4-2-5 
5-3 
* 
—2-6 
4-3-5 
6-1 
-3-5 
4-2-5 
6-0 
1 
— 2-5 
+ 2-3 
4-8 
-2-5 
4-3-8 
6-3 
— 0-6 
+4-5 
5-1 
— 2-2 
4-3-2 
5-4 
-2 
-0-9 
+ 3-9 
4-8 
-2-3 
+3-0 
5-3 
-3-0 
4-2-5 
5 - 5 
-5-0 
4-0-8 
5-8 
02 
-2-8 
+4-2 
7-0 
+ 1-0 
-)-6-5 
5-5 
Mean 
.. 5-66 
Mean 
.. 5-61 
r* 
+4-0 
+ G-5 
2-5 
0-0 
+ 2-3 
2-3 
‘■Z 
-0-7 
4-1-6 
2-3 
-1-8 
4-0-8 
2-6 
m 
-3-5 
-0-8 
2-7 
-1-0 
+ 1-3 
2-3 
g . 
-3-8 
-1-0 
2-8 
+ 0-2 
4-2-3 
2-1 
-d rt 
£.2 
— 0-5 
+ 1-8 
2-3 
0-0 
4-2-2 
2-2 
o 
-2-0 
4-0-1 
2-1 
-0-6 
4-2-0 
2-6 
J ^ 
-0-8 
+2-2 
3-0 
-0-6 
4-L8 
2-4 
—1-3 
+ 1-6 
2-9 
+ 0-5 
+2:9 
2-4 
Mean 
.. 2-57 
Mean 
.. 2-36 
difference in the smoothness of the surfaces. Of the three, according to hardness cast 
iron should have given the least results ; and so it does, as far as starting from rest is 
concerned, although when rolling back the result is the other way. Box-wood appears 
to offer about double the resistance of cast iron ; and india-rubber about ten times as 
much in the case of rolling back, and six times as much in starting from rest. 
Table VI. — Showing the Mean of the Results for the various conditions of the 
Surface and manner of Starting. 
The nature of the Surface. 
Starts from rest. 
Started in the opposite 
direction. 
Mean. 
Clean. 
Oiled or 
blackleaded. 
Clean. 
Oiled or 
blackleaded. 
Cast iron 
5-66 
5-61 
2-57 
2-36 
4-05 
Glass 
6-32 
5-96 
1-93 
2-56 
4-19 
Brass 
7-75 
6-53 
2-07 
2-587 
4-73 
Box-wood 
10-05 
9-25 
5-71 4 ' 
2-34 
7-09 
India-rubber 
35-37 
38-75 
31-87 
28-00 
33-24 
9 
A 
MDCCCLXXYI. 
