[farmer] determination OF COEFFICIENT OF DISCHARGE 



57 



due to gravity is here eliminated, and the results therefore apply to the 

 effect due to impact alone. 



TABLE II. VALUES OF COEFFICIENT OF IMPACT C, FOR FLAT 



SURFACES. 



These results have been plotted in Diagrams II.-V. 



Diagram II. has been i^lotted with a view of showing the variation 

 of the coefficient with the velocity of the impinging jet, and the coeffi- 

 cient of impact is therefore plotted as an ordinate upon a velocity base. 

 It is evident that the curve obtained by inserting all the values obtained 

 at both distances— two and four feet^ — would be a very inconsistent one, 

 owino; to the different conditions of motion at different distances from the 



ViLociTf /CLOc/rr 



Diagram II. Diagram III. 



oiifice ; so the course is taken of plotting the values got at each distance 

 in a separate table. It is not suggested that the conditions of varying 

 velocity are exactly identical at the same distance from the orifice, what- 

 ever be the head under which the jet is issuing ; but owing to the ab- 

 sence of any reliable theory on this subject, that probably forms the best 

 available standard of comparison. 



Diagram II. thus shows graphically the coefficient of impact as 

 obtained from observations taken at a distance of two feet from the 

 orifice, while Diagram III. illustrates the same thing for four foot distance. 



Sec. III., 1896. 5. 



