92 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 62 



This leads to the equation to a straight Hne drawn on figure 39, 

 K 



DW 



= .ooi8 + .ooio3F. 



It appears that for velocities above 20 feet per second the values of 



^ ,2 16 ZO ZH £8 3Z 36 Vo VV ■W J? J6 «o 



Fig. 39.-Units. q g f^_ ^j^j.^ 



□ 5 " " 



7? ^ Pounds, force. 



D =: Feet, diameter. 



V = Feet per second, velocity 



X 4 " 

 A 3 " 



A 2 " 



R 



as observed for all disks lie near the line. It should be noted 



that the above expression is not dimensionally homogeneous, and it 

 is therefore not safe for extrapolation. However, it was pointed out 

 that the disks used were of uniform thickness and hence not geo- 

 metrically similar. 



