ROYAL SOCIETY OF CANADA 



It will bo noticed that in eveiy case the actual force falls away con- 

 siderably i'rom the theoretical one. Even allowing a large value for the 

 coefficient of velocity there still remains a loss of force amounting to 

 three or four per cent of that given bj' theory. For this loss it seems 

 difficult to account, as it would appear that the frictional and other effects 

 of the vane would all act in a plane perpendicular to the path of the jet, 

 and that all the momentum of the stream in the original direction, being 

 completely destroyed. Avould have an exact counterj)art only in the actual 

 force produced upon the vane. 



Beyond this general fact it is evident from both diagrams that there is 

 an increase in the coefficient as the velocity increases; but the information 

 acquired is not sufficient to lead to the formation of a law of variation. 



9400 .A^i 



i.oa' û/4/trrffi 10.51" 

 Diagram IV. 



Zù^' DiAfiCre/) 10 bl 1166 



Diagram V. 



It is also interesting to notice the variation of the coefficient as the 

 diameter and consequently the area of the vane is increased. For this 

 purpose Diagrams lY. and V. arc given in Avhich the diameters of the 

 vane are taken as abscissa* and the coefficients as-ordinates. 



The coefficient of impact diminishes as the radius decreases from 12 

 to 10'51 inches, but does not continue to fall at the next observation ; on 

 the contrary, the value for the 8" diameter is apjn-oximately equal to that 

 for the 11-66" diameter. 



Besides the flat vanes experiments were made with curved vanes or 

 buckets of different descriptions. These, like the flat vanes, were made 

 of sheets of copper and were spun to the shape required. These vanes 

 arc each surfaces of revolution, the curves from whicli they are generated 

 being parts of a circle, an ellipse, and a hj^perbola. The principal dimen- 

 sions of these curves are : 



Circle — Diameter 12" 

 Ellipse — Semi-major axis 12" 

 Semi -minor axis 6'93" 

 4i/3 inches 

 Parabola — Latus rectum 6", 



