WITH WHICH AIR RUSHES INTO A VACUUM. 



157 



ture, which in this case remained unchanged. Recogniz- 

 ing the fact that when air of 15 lb. effective pressure was 

 discharged into the atmosphere the cylinder actually con- 

 tained two atmospheres of absolute pressure, we are led to 

 the conclusion that the phenomenal increase in the rate of 

 discharge observed is caused by the external atmosphere 

 acting as a vacuum, and offering no resistance to the dis- 

 charge into it of air of 15 lb. pressure, which thereby be- 

 comes 30 lb. effective pressure. The velocity of air of 1 5 lb. 

 effective pressure discharged into the atmosphere based on 

 this conclusion is 1021 feet per second, the same as the 

 velocity found for the discharge into a vacuum. For 

 effective pressures below 15 lb. the velocities are com- 

 pounded of the rate of discharge into a vacuum, and the 



Table IV. — Discharge into the Atmosphere. 

 Barometer 29'64. Thermometer 58° F. 



Effective pres<sui-e, 



Time of dis- 



Apparent 



Velocity- 



in pounds pei* 



charge, in 



velocity, per 



coefficient 



square inch. 



seconds. 



second. 



•62. 



120 



7-5 



843 



1360 



"5 



775 



852 



1374 



no 



8-0 



862 



1390 



105 



8-5 



852 



1374 



100 



9-0 



843 



1360 



95 



9*5 



842 



1360 



90 



lO'O 



843 



1360 



85 



IO-5 



851 



1372 



80 



ii"o 



863 



1392 



75 



I2."0 



844 



1362 



70 



13-0 



836 



1348 



65 



i4'o 



833 



1344 



60 



15-0 



843 



1360 



55 



i6-5 



837 



1350 



5° 



i8'o 



843 



1360 



45 



20-0 



843 



1360 



40 



22'0 



863 



1392 



35 



24-5 



886 



1429 



30 



ayo 



935 



1509 



25 



3i"o 



980 



1581 



20 



36-0 



1053 



1699 



15 



43-0 



1178 



1900 



10 



58-0 



1311 



2114 



