156 



MR. H. WILDE ON THE VELOCITV 



Table III. — Discharge into the Atmosphere. 

 Barometer 30* 1 7. Thermometer 59° F. 



Effective pres- 



Time of 



Apparent 



Velocitj'- 



sure, in pounds 



discharge, in 



velocity, per 



coefficient 



per square inch. 



seconds. 



second. 



•62. 



15 



8-0 



1266 



2043 



14 



8-25 



1318 



2126 



13 



8-5 



1373 



2214 



12 



9-0 



141 3 



2280 



II 



9-5 



1454 



2345 



10 



lO'O 



1519 



2450 



9 



IO-5 



1609 



2595 



8 



ii-S 



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 



above described. The results are shown in Tables III. 

 and IV. 



On comparing the times of discharge in Table III. and 

 the velocities calculated therefrom with the times and 

 velocities in Table II., a remarkable difference will be 

 observed in them for the same effective pressures. Thus, 

 the velocity of discharge from 15 lb. to 14 lb. appears to 

 be double that assigned to the same pressure when the 

 discharge is made into a vacuum ; while in the discharge 

 from 2 lb. to I lb. (the lowest pressure in the Table) the 

 velocity appears to be more than six times greater, or 

 4219 feet per second. No less remarkable than this 

 apparent increase in the rate of discharge is the complete 

 inversion of the order of the velocities as compared with 

 those when the discharge M'as made into a vacuum for the 

 same effective pressure. Now, we have knowledge of 

 several causes competent to diminish the velocity of air 

 of constant temperature flowing into the atmosphere, but 

 none to increase the velocity except the form of the aper- 



