156 
MR. RENNIE’S EXPERIMENTS ON THE FRICTION AND 
Table VI. 
Experiments on extent of surface with Metals. 
wt. 
to be 
moved. 
Weight 
required to 
move it. 
Propor- 
tion. 
Weight to 
1 inch 
of area. 
Weight 
required to 
move it. 
Propor- 
tion. 
Weight to 
1 inch 
of area. 
wt. 
to be 
moved. 
Weight 
required to 
move it. 
Propor- 
tion. 
Weight to 
1 inch 
of area. 
Weight 
required to 
move it. 
Propor- 
tion. 
Weight to 
1 inch 
of area. 
Laid flat. 
Laid edgewise. 
Laid flat. 
Laid edgewise. 
Cast Iron on Cast Iron. 
Hard Brass on 
Cast Iron. 
Area of 
surface 44 inches. 
Area 6f inches. 
Area of surface 48 inches. 
Area 7f inches. 
lbs. 
lbs. 
oz. 
lbs. 
OZ. 
lbs. 
OZ. 
lbs. 
OZ. 
lbs. 
lbs. 
OZ. 
lbs. oz. 
lbs. 
OZ. 
lbs. oz. 
14 
2 
o 
6.58 
0 
5.09 
2 
4 
6.20 
2 
1.1 
14 
1 
14 
7.4 
0 4-i- 
1 
11 
8.3 
1 12 
24 
3 
3 
7.53 
0 
8.72 
3 
11 
6.50 
3 
8.8 
24 
3 
5 
7.2 
0 8 
4 
0 
6.0 
3 1 
36 
4 
14 
7-38 
0 
13.10 
5 
14 
6.12 
5 
5.3 
36 
4 
9 
7.8 
0 12 
6 
0 
6.0 
4 10 
48 
6 
8 
7.38 
1 
1.40 
7 
10 
6.30 
7 
1.7 
48 
6 
4 
7.6 
1 0 
7 
13 
6.1 
6 3 
60 
8 
4 
7.27 
1 
5.80 
9 
8 
6.30 
8 
14.2 
60 
7 
12 
7.7 
1 4 
9 
0 
6.6 
7 11 
72 
10 
0 
7.20 
1 
10.20 
11 
7 
6.29 
10 
10.6 
72 
9 
12 
7.3 
1 8 
11 
0 
6.5 
9 4 
84 
11 
10 
7-23 
1 
14.50 
13 
5 
6.31 
12 
7.1 
84 
11 
8 
7.3 
1 12 
13 
2 
6.4 
10 13 
96 
13 
12 
6.98 
2 
2.90 
15 
5 
6.27 
14 
3.5 
96 
i 13 
1 
1 
7.3 
2 0 
14 
8 
6.6 
12 6 
Yellow Brass on 
Cast Iron. 
Tin on Cast Iron. 
Area of surface 44 inches. 
Area 6f- inches. 
Area of surface 44 inches. 
Area inches. 
lbs. 
lbs. 
OZ. 
lbs. 
OZ. 
lbs. 
OZ. 
lbs. 
OZ. 
lbs. 
lbs. 
OZ. 
lbs, oz. 
lbs. 
OZ. 
lbs. oz. 
14 
1 
15 
7.22 
0 
5.09 
2 
1 
6.79 
2 
1.1 
14 
2 
8 
5.60 
0 5.1 
2 
12 
5.09 
2 1.1 
24 
3 
7 
6.98 
0 
8.72 
3 
8 
6.85 
3 
8.8 
24 
4 
7 
5.40 
0 8.7 
4 
8 
5.33 
3 8.8 
36 
5 
6 
6.70 
0 
13.10 
5 
1 
7.11 
5 
5.3 
36 
6 
0 
6.00 
0 13.1 
6 
7 
5.59 
5 5.3 
48 
7 
3 
6.67 
1 
1.40 
6 
10 
7.24 
7 
1.7 
48 
8 
7 
5.68 
1 1.4 
8 
14 
5.40 
7 1.7 
60 
9 
3 
6.53 
1 
5.80 
9 
3 
6.53 
8 
14.2 
60 
9 
13 
6.11 
1 5.8 
9 
13 
6.11 
8 14.2 
72 
11 
5 
6.36 
1 
10.20 
10 
5 
6.98 
10 
10.6 
72 
12 
5 
5.84 
1 10.2 
11 
13 
6.09 
10 10.6 
84 
13 
5 
6.30 
1 
14.50 
13 
12 
6.10 
12 
7-1 
84 
14 
5 
5.86 
1 14.5 
14 
5 
5.86 
12 7-1 
96 
15 
13 
6.07 
2 
2.90 
15 
1 
6.37 
14 
3.5 
96 
16 
4 
5.90 
2 2.9 
16 
4 
5.09 
14 3.5 
From the foregoing experiments it appears that the friction of 
Cast iron upon cast iron laid flat, varies from 6.58 to 7.53 
Cast iron upon cast iron laid edgewise, varies from 6.2 to 6.5 
Of hard brass upon cast iron laid flat, varies from 7.2 to 7.8 
Of hard brass upon cast iron laid edgewise, varies . . . . from 6.0 to 8.0 
Of yellow brass upon cast iron laid flat, varies from 6.09 to 7.22 
Of yellow brass upon cast iron laid edgewise, varies . . . from 6.1 to 7.24 
Of tin upon cast iron laid flat, varies from 5.4 to 6.11 
Of tin upon cast iron laid edgewise, varies ...... from 5.09 to 6.11 
That the friction is nearly the same with cast iron and brass whether the load be applied on the 
broad side or on the narrow side of the plates, although the areas of the surfaces are to each other 
as 6.22 : 1. 
That tin being a softer metal and more easily abraded : the friction increases when a load is ap- 
plied above 8lbs. per square inch, but remains nearly the same with the broad side as with the 
narrow side. Generally speaking, the friction is less with the broad side than with the narrow side. 
