GYRO STATIC ACTION 



37 



contained in a solid steel disk 2 feet thick, 10 feet in diameter and 

 rotating at a speed of 144 revolutions per minute; and therefore this 

 amount of rolling torque continued for one tenth of a second would 

 bring the axle of such a wheel into a horizontal position so that any- 

 further continuation of the torque would cause the ship to roll. 



The rolling motion of a ship, however, is largely an oscillatory 

 motion which is slowly built up by a succession of waves in synchron- 

 ism with the proper period of rolling motion, and excessive rolling may 

 therefore be prevented by an action which tends to hinder the oscilla- 

 tions by friction. A very considerable amount of frictional damping 

 may be produced by a moderately small gyrostat arranged as shown 

 in Fig. 32 (plane of paper in Fig. 32 is a vertical plane containing the 

 keel of the ship). In this case the rolling motion of the ship causes 

 the pendant wheel and axle to oscillate to and fro in the plane of the 

 keel, and these oscillations are hindered by the motion of a piston in a 

 dash-pot as indicated in the figure. 



The Bkenkant Monorail Car 



Before discussing the Brennan gyrostatic mechanism for main- 

 taining the equilibrium of a monorail car, let us consider the action of 

 the apparatus shown in Figs. 33 to 36, a gyrostat wheel mounted in a 

 frame aa which in turn is pivoted in a larger frame BB, the whole 



Pig. 33. 



Fig. 34. 



being supported upon two legs, one behind the other, as seen in the 

 figures. Standing in the position shown in Fig. 33, the framework 

 is acted upon by the unbalanced pull of the earth which produces a 

 torque ; the spin-momentum which is continually produced by this torque 

 is absorbed by a precessional motion P of the gyrostat wheel as it 



