182 mr. h. wilde on the efflux of air as 



Air. 



^5 = 2-413 (feet per second) -\/ ' V . 



Vw= -997 (feet per second) \/ '\bi 



XII. On the Efflux of Air as modified by the Form of the 

 Discharging Orifice. By Henry Wilde, Esq. 



Eead March 23rd, 1886. 



In my former paper on the efflux of air, the hydraulic 

 coefficient "62, as commonly applied to the discharge of 

 elastic fluids through an orifice in a thin plate, was taken 

 as the value of the conti^action of such orifice, and from 

 this coefficient the highest velocities shown in the several 

 Tahles were deduced. A review of the results of my expe- 

 riments by Prof. Osborne Reynolds* led me to doubt the 

 value of this coefficient, and to make further experiments 

 with the object of determining the maximum rate of 

 discharge from an orifice of the best form. 



Five disks of brass had each a hole drilled through its 

 centre two-hundredths of an inch in diameter. Equality 

 in the size of the holes was accurately determined by 

 means of a standard cylindrical gauge. These disks I 

 shall designate A, B, C, D, E. 



* Proceedings Manchester Lit. and ,Phil. Society, vol. xxv. p. 55, or 

 present vol. of Mem. p. 1 64. 



