26 
being greater in proportion to that of the circumference of a 
larger orifice, was proved by discharging air of 15 lbs. pres- 
sure through a hole one-hundreth of an inch in diameter 
in another similar thin plate, when the times of discharge 
through the short range of 1 lb. of pressure were found to 
be in the ratio of 4 to 1, or inversely as the areas of the 
orifices. 
Taking into further account the difference between the 
initial and terminal velocities due to the reduction of pres- 
sure from 151bs. to 141bs., the results of these experiments 
show, that an absolute pressure of 30 inches of mercury, and 
at a temperature of 60° Fahrenheit, the atmosphere rushes 
into a vacuum with a velocity not greater than 1050 feet 
per second, or less than the velocity of sound. 
Some anomalous rates of discharge which I obtained, 
when air of different densities was discharo^ed into the 
atmosphere, induced me to repeat the experiments with the 
same apparatus and under precisely the same conditions as 
those which had been made into a vacuum as above described. 
The results are shown in tables III. and IV. 
Table III. 
Discharge into the Atmosphere. 
Barometer SOT 7. Thermometer 59°. F. 
Effective 
pressure in lbs. 
per 
square inch. 
Time of 
discharge 
in 
seconds. 
Apparent 
velocity 
per second. 
Velocity 
coefficient 
•62 
15 
8-0 
1266 
2043 
14 
8-25 
1318 
2126 
13 
8-5 
1373 
2214 
12 
9-0 
1413 
2280 
11 
9-5 
1454 
2345 
10 
10-0 
1519 
2450 
9 
10-5 
1609 
2595 
8 
11-5 
1652 
2664 
7 
12-5 
1734 
2797 
6 
13-5 
1876 
3026 
5 
15-5 
1985 
3202 
4 
17-5 
2110 
3403 
3 
22-0 
2300 
3710 
2 
29-0 
2616 
4219 
