MR. RENNIE ON THE FRICTION AND RESISTANCE OF FLUIDS. 431 
Table III. 
Experiments on the Rotations of Iron Discs and Wooden Balls moving in 
Air, with their planes perpendicular to the plane of the horizon. 
Time in descending. 
Weight 
suspended. 
Height fallen. 
Two circu- 
lar discs 
10| inches 
diameter. 
Area SI 
inches. 
Velocity 
per 
second. 
Two square 
fans. Area 
81 inches. 
Velocity 
per 
second. 
Two 
wooden 
balls lOf 
inches 
diameter. 
Velocity 
per 
second. 
lbs. 
2 
4 
9 
16 
20 
The spindle made 
15.9 turns in fall- 
ing 25 feet. Mean 
circle 5 1 .83 would 
move through 
68.67 feet. 
seconds. 
10.00 
6.00 
4.50 
3.00 
2.50 
feet. 
6.867 
11.445 
15.261 
22.891 
27-469 
seconds. 
10.00 
7.00 
4.50 
3.25 
3.00, 
feet. 
6.867 
9.810 
15.261 
21.130 
22.891 
seconds. 
23 
13 
8 
7 
6 
feet. 
2.984 
5.282 
8.584 
9-810 
11.445 
Conclusions. 
] . That the resistances are as the squares of the velocity. 
2. That the comparative resistances between discs and globes are as two to one nearly. 
Table IV. 
Experiments on the Resistance of Iron Discs and Wooden Globes revolving- 
in Water. 
Weight. 
Height fallen. 
Time in descending. 
Two circu- 
lar discs, 
81 inches 
area. 
Velocity 
per 
second. 
Two 
square fans, 
9 inches 
square, 
81 inches 
area each. 
Velocity 
per 
second. 
Two 
wooden 
balls. Area 
81 inches. 
Velocity 
per 
second. 
seconds. 
feet. 
seconds. 
feet. 
seconds. 
feet. 
16 
The spindle made 
15.9 turns in fall- 
63 
1.09 
53 
1.29 
15.00 
4.57 
20 
ing 25 feet. Mean 
54 
1.27 
48 
1.43 
14.00 
4.90 
32 
circle 5 1 .83 would 
43 
1.59 
40 
1.71 
10.50 
6.59 
40 
move through 
40 
1.71 
35 
1.96 
9-50 
7.22 
64 
824.19 inches or 
30 
2.28 
28 
2.45 
8.00 
8.58 
256 
68.67 ieet. 
14 
4.90 
15 
4.57 
5.00 
13.73 
3 K 
MDCCCXXXI. 
