Spoke and Disc Wheels 119 



than thirteen times the torque when the pulley ends were closed. The 

 horse power in each case was as follows: 



Open pulley, 1,840 r.p.m 0.2463 h.p. 



Closed pulley, 1,850 r.p.m 0.0183 h.p. 



Difference in favor of closed pulley 0.228 h.p. 



Note that the air friction losses in the case of this flat spoke 12x6 

 wood pulley running at 1,840 r.p.m. were greater than the losses for 

 all seven of the narrow face cast iron pulleys running at 650 r.p.m. 

 This is due in part to the fact that the wood pulley was run at a higher 

 rotational speed. However, the peripheral speed was not much higher 

 than in the case of the cast iron pulleys of larger diameter. 



Waterman Institute, Indiana University. 

 Riverbank Laboratories, Geneva, Illinois. 



