1,6 



here in fig. 7 is a vertical mill, the motion of the wheel being 

 vertical. The sails of a horizontal mill move horizontally. 



FIG. 7. THE AEROMOTOR (POWER-MILL). 



150. Useful tables. A few tables regarding velocity of 

 wind &c., may be found very useful in connection with the 

 question of efficiency of wind-mills. 



