236 MOTIONS OF THE GYROSCOPE 



the standard point." The disc and all the con- 

 nected parts of the gyroscope are free to move in 

 any direction. 

 A 



66. 



If the weight w be placed near the fulcrum c, 

 so as slightly to underbalance the disc, beside 

 rotating rapidly on its axis, it begins a slow orbi- 

 tal revolution in the direction in which the under- 



i 



side of the disc is moving. 



By attaching the arm and counterweight so as 

 to balance the disc exactly on the pointed stand- 

 ard, the orbital revolution ceases, while the axial 

 rotation continues till the impulse is exhausted. 



By overbalancing the disc, the horizontal revolu- 

 tion is persistently maintained, but changed to an 

 opposite direction, the direction in which the top 

 of the disc is turning. During the three changes 

 the disc rotates in a constant direction. 



