modified by the Form of the Discharging Orifice, 



Table II. 

 Discharge into the Atmosphere. 



497 



Lb. per 

 square inch 

 effective pres- 

 sure. 



S a 



Plain tube- 

 orifice. 



Conoidal 

 orifice 

 inside. 



Oonoidal 

 orifice 

 inside. 



Oonoidal 

 orifice 

 outside. 



Conoidal 

 orifice 

 inside. 



Oonoidal 

 orifice 

 outside. 



Double 

 conoidal 

 orifice. 



OB . 



d o 



.£«d 



o '£ 



Jg o 



O o 









A 



B 











D 



D 



E 



O 





sec. 



sec. 



sec. 



sec. 



sec. 



sec. 



sec. 



sec. 





15 



16-0 



13-5 



14-0 



140 



14-0 



145 



14-5 



15-0 



•829 



13 



17-5 



14-5 



15-0 



150 



150 



16-5 



16-0 



16-0 



•829 



11 



19-5 



160 



16-5 



16-5 



16-5 



18-5 



180 



17-5 



•820 



9 



22'5 



18-0 



18-5 



18-5 



18-5 



20-5 



19-5 



19-0 



•818 



7 



26-0 



21-0 



21-5 



22-0 



215 



! 240 



21-5 



22-0 



•808 



5 



33-0 



26-0 



26-5 



27-5 



26-5 



300 



25-5 



27-0 



•788 



3 



51-0 



39-0 



40-5 



42-5 



40-5 



! 47-0 



38-5 



42-5 



•765 



the coefficients for the highest and lowest pressures in this 

 table being *935 and *940 respectively ; whereas the co- 

 efficients for the same orifices in Table II. are *829 and "765 

 respectively. Again, while there is little difference in the 

 times of discharge from the tubular orifices among themselves, 

 a remarkable change occurs during the fall of pressure from 

 15 lb. to 1 lb. when the discharge is made through C and D 

 with the conoidal orifices outside the vessel. 



The discharge through D from 15 lb. to 13 lb. is the same 

 whether the conoidal orifice is inside or outside ; but in the 

 latter position, as the pressure diminishes, the rate of discharge 

 increases, till at the lowest pressure this increase amounts to 

 8*5 seconds, and exceeds the maximum discharge from the 

 tube-orifice A. A similar change is also noticeable in the 

 rate of discharge through reversing the orifice C ; but as the 

 change does not come on before the pressure is below 7 lb., 

 it is less marked than when the discharge is made through D. 



Suspecting that the phenomenal change in the rate of 

 discharge for the same orifice was due to the varying resist- 

 ances of the discharging and receiving atmospheres of pres- 

 sure described in my former paper, the discharges from the 

 orifices O, A, and D were made into a vacuum of 1*5 inch 

 of mercury instead of into the atmosphere, and the times of 

 discharge were recorded for each reduction of 1 lb. of pressure. 



The results are shown in the table. 



