ABRASION OF THE SURFACES OF SOLIDS. 
165 
Experiments with Oil. 
Weight in 
roller scale. 
Weight required 
to move the roller. 
Height 
fallen. 
Time in falling. 
Remarks. 
Proportion. 
1st half. 2nd half. 
lbs. 
oz. 
lbs. 
OZ. 
Seconds. 
62 
8 
7 
0 
12 
8.92 
62 
8 
7 
0 
17! 
8.92 
62 
8 
7 
0 
11 
22 
8.92 
62 
8 
7 
0 
9 
18 
8.92 
62 
8 
7 
0 
8 
16 
8.92 
62 
8 
7 
0 
8 
16 
Found the velocity too 
8.92 
62 
8 
7 
0 
21 feet 
8± 
17 
great; made an addi- 
8.92 
62 
8 
14 
0 
3 
5 1 
tion of 21£lbs. making 
4.46 
62 
8 
14 
0 
3 
4 
which brought it re- 
4.46 
62 
8 
14 
0 
3 
5J 
gular. 
4.46 
84 
0 
14 
0 
H 
7 
This weight produced a 
6.00 
84 
0 
14 
0 
H 
7 
regular velocity. 
6.00 
84 
0 
14 
0 
H 
7 
6.00 
Experiments with Tallow. 
lbs. 
OZ. 
lbs. 
OZ. 
Seconds. 
272 
8 
42 
0 
14 
28 
6.48 
272 
8 
42 
0 
H 
13 
6.48 
272 
8 
42 
0 
H 
13 
6.48 
272 
8 
42 
0 
n 
14 
6.48 
REMARKS. — The irregularity of the resistances observed in the first seven experiments arose 
from the impartial contact and consequent grinding or abrading of the surfaces. The roller having 
attained its bearing, and the weight in the roller-scale being diminished, the irregularity ceased, 
especially when oil and tallow were used. 
From the result of these experiments it will be seen, that friction did not increase with an increase 
of velocity. The time in falling the whole height of twenty-one feet being double the time in falling 
half the height. These experiments were likewise illustrated (but not so satisfactorily,) by a machine 
somewhat similar to that of Mr. Roberts. — The pulley was sufficiently distant from the roller to 
render the angle of tension imperceptible. 
Appendix to Table X. 
Friction of the cord and weight on the axles 
of the iron rollers, to be deducted from the 
foregoing experiments. 
Weight in 
each end. 
Total of weights. 
Weight required to 
overcome the friction 
of the cord. 
lbs. 
lbs. 
lbs. oz. 
56 
112 
4 8 
112 
224 
7 0 
168 
336 
11 4 
224 
448 
14 0 
