ABRASION OF THE SURFACES OF SOLIDS. 
167 
Table XII. Experiments on the Friction of Hide Leather. 
Twelve pieces of hide leather were placed parallel to each other in a wooden 
box, with one side loose so as to admit of being adjusted according to the 
number of pieces of leather ; a bolt was then passed through the whole, and a 
nut screwed on the end of the bolt so as to compress the pieces of leather 
together and permit them to act on edge as one uniform surface ; which surface 
was increased or diminished by putting in or taking out some of the pieces of 
leather and screwing up the nut as before. 
Friction of 9 square inches of leather soaked in water, moving over a plate of iron. 
7 lbs. barely kept in motion 36 lbs. after starting with the hand. After remaining 5 minutes it took 
to start it 29 lbs. 28 lbs. barely kept in motion 64 lbs. after starting it, and after remaining one mi- 
nute it took 42 lbs. to start it. 
Surface 1^ by 3 inches, equal to 4 \ inches area. 
65 lbs. barely kept in motion 36 lbs. after starting it. After remaining 5 minutes it took 21 lbs. 
to start it. 21 lbs. barely kept in motion 64 lbs. after starting it. After remaining 5 minutes it took 
38 lbs. to start it. 
Friction of Hide Leather moving dry over a surface of Cast Iron. 
Weight on 
Surface. 
Weight re- 
quired to 
move it. 
Propor- 
tion. 
Space 
passed 
over. 
Time. 
Weight 
per inch 
Area. 
Weight on 
Surface. 
Weight re- 
quired to 
move it. 
Propor- 
tion. 
Space 
passed 
over. 
Time. 
Weight 
per inch 
Area. 
Area of surface 9 square inches. 
Area of surface 4§ 
square inches. 
lbs. 
lbs. 
cz. 
inches. 
sec. 
lbs. 
lbs. 
lbs. 
OZ. 
inches. 
sec. 
lbs. 
6 
1 
8 
4.0 
.66 
6 
1 
2 
5.33 
1.33 
7 
1 
12 
4.0 
.77 
7 
1 
5 
5.33 
1.55 
8 
2 
0 
4.0 
1 ft 
1 Q 
.88 
8 
1 
9 
5.12 
1.77 
36 
8 
12 
4.1 
l o 
4.00 
36 
7 
3 
5.00 
1 O 
I o 
8.00 
49 
12 
0 
4.0 
5.44 
49 
9 
5 
5.26 
10.88 
64 
16 
0 
4.0 
7-11 
64 
13 
10 
4.69 
14.22 
Area of surface 6f; square inches. 
Area of surface square inches. 
lbs. 
lbs. 
oz. 
inches. 
sec. 
lbs. 
lbs. 
lbs. 
OZ. 
inches. 
sec. 
lbs. 
6 
1 
4 
4.80 
.88 
6 
1 
1 
5.64 
2.66 
7 
1 
8 
4.66 
1.03 
7 
1 
3 
5.89 
3.11 
8 
1 
12 
4.57 
1 Q 
1.18 
8 
1 
8 
5.33 
18 
18 
3.55 
36 
7 
4 
4.96 
1 O 
lo 
5.33 
36 
7 
1 
5.09 
16.00 
49 
11 
0 
4.45 
7-25 
49 
9 
1 
5.40 
21.77 
64 
14 
0 
4.57 
9-48 
64 
13 
2 
4.87 
28.44 
REMARKS. — The friction of hide leather soaked in water appears to be greatly increased by time 
and weight. This circumstance explains the enormous friction evinced in the pistons of pumps when 
first put in motion. When the leather is not soaked, the resistance varies from one ^th to nearly one 
£th of the pressure, and is diminished (caeteris paribus) by a diminution of surface. 
