36 



THE POPULAR SCIENCE MONTHLY 



spin-momentum produced by an unbalanced torque T' would be com- 

 pletely absorbed by tbe precessional motion of the spinning wheel as 

 its axis of spin turns in the direction of the curved dotted arrow P', 

 and the spin-momentum produced by an unbalanced torque T" would 



wheels, 



nam 



~-hinge 



mini 



— -^r guide 



P'^*- 



r 



AS 



j<ii 



+*P" 



Fig. 31. 



be completely absorbed by the precessional motion of the spinning 

 wheel as its axis of spin turns in the direction of the curved dotted 

 arrow P" . 



dash-po t 

 7ZZZZZZZZZZZZZ2ZZZZZZZZZZZ2 



W;/;;;;;M; m;;;»;;»/», 



Fig. 32. 



To completely hinder the rolling motion of a ship in this way would 

 require the use of a very large wheel rotating at high speed. Thus 

 a rolling torque (T or T" in Fig. 31) equivalent to 200 tons placed 

 10 feet to one side of the axis of the ship and continuing for only one 

 tenth of a second would represent the whole amount of spin-momentum 



