MODIFIED BY THE DISCHARGING OBIFICE. 



Table III. — Discharge into a Vacuum 1*5 inch 

 Mercury. 



187 



Lb. per 



Hole 



Plain 



Oonoidal 



Conoidal 



Coefficient 



square 



inch 



absolute 



in thin 



tube 



orifice 



orifice 



for 



plate. 



orifice. 



inside. 



outside. 



orifice. 



pressure. 







A 



D 



D 









sec. 



sec. 



sec. 



sec. 





15 



160 



15-0 



i6*o 



i6-o 



•937 



14 



17-5 



i6-5 



i8-o 



i8-o 



■943 



13 



19-0 



17-5 



20-0 



20-0 



•921 



12 



2I-0 



19-5 



22'5 



22-0 



•928 



II 



23-0 



21-5 



24-5 



24-0 



•935 



10 



25-5 



24"0 



27-5 



27-0 



-941 



9 



^8-5 



27"0 



31-0 



30-5 



■947 



8 



32-5 



3i'o 



35-5 



35-0 



■954 



7 



37"5 



35'5 



41-0 



40-0 



•947 



6 



45-0 



42-5 



49-5 



48-S 



■944 



5 



55-0 



52-5 



63-0 



6i'o 



•955 



4 



70-0 



67-0 



8i-o 



79-0 



mean 



3 



I02-0 



lOI'O 



125-0 



I20-0 



coefficient 



2 



iSo'o 



1920 



241-0 



224-0 



•941 



A comparison of the times of discharge through D with 

 the conoidal orifice in both positions will show that they 

 approach nearly to a ratio of equality. The phenomenal 

 change in the rate of discharge from the same orifice 

 was consequently due to the diminished resistance of the 

 external atmosphere, the conoidal form of the orifice in- 

 creasing the amount of rarefaction above that obtained 

 with a plain tube orifice. This conclusion is further 

 evident on comparing the times of discharge from D in 

 reversed positions from a pressure of 3 lbs. to i lb. ; for as 

 the rarefaction in the vacuum-chamber was only reduced 

 to I '5 inch of mercury, the phenomenal change in the 

 rate of discharge again presents itself, making a diff^erence 

 of 17 seconds in the times of discharge between the 

 reversed position of the orifice for the lowest pressure. 



Comparing the times of discharge through the tube 

 orifice A and the orifice O in the thin plate, it will be seen 

 that there is much less difference between them than for 



