1891.] On the Pressure of Wind on Curved Vanes. 



43 



The diagrams showing the way in which the normal component of 

 the pressure varies with the angle of incidence have been obtained by 

 taking the mean values from positions I and II. In drawing the 

 curves, the want of observations at the intermediate angles was felt, 

 but I do not think that further experiments would greatly modify 

 the forms obtained. 



A few observations with the plate in the other position, i.e., with 

 the axis of the cylinder parallel to the long arm of the whirling 

 machine, have been made. They are given in Tables IV and V. 



In Tables I, II, IV, and V the results have been reduced to pres- 

 sures per sq. ft. ; this has been done by multiplying by 12/11*7 and 

 12/9 respectively. In Table III, the rectangle contained by the two 

 straight edges and the chords of the curved edges contains 1 sq. ft. 

 (the length being 28*8 in.) ; hence in this case no reduction is 

 necessary. 



Table I. Axis of Cylinder inclined to the Wind. 

 FIG. 1. 



of cylinder 



Concave surface facing the wind. 

 Position I. Position II. 



Angle of 

 incidence. 



Value of 

 moment. 



135, 121,116,117 



20 113, 118 



40 108 



45 Ill 



50 107,109 



60 108 



*70 *89 



*80 , ..*59 



Angle of Value of 



incidence. moment. 



20" .... 136, 131, 120, 117 



30 .... 129, 121, 107, 114, 110 



40 .... 128,130 



45 .... 135, 131, 113, 113 



50 139, 120, 113, 123, 108 



55 .... 138, 125, 127 



60 .... 126, 130, 134, 138 



70 .... 96, 100, 96, 98 



