MIRACLES OF SCIENCE 



of this resistance, it is necessary to experiment with 

 a gyroscope suspended in gimbal rings in such a way 

 that it has freedom of motion in three directions. 

 That is to say, the axis of the spinning wheel is fixed 

 in a ring which itself can revolve at right angles to the 

 axis, this ring being also free to revolve in a second 

 outer ring. 



If now, a gyroscope so adjusted is set rotating, 

 with its axis in a horizontal plane, and an attempt 

 is made to shift the axis horizontally, the actual shift 

 will not be horizontal, but directly upward or down- 

 ward. But if, on the other hand, an attempt is made 

 to shift the axis upward or downward, the actual shift 

 will be horizontal. In other words, the resultant 

 motion when any force is applied to the axis of the 

 gyroscope is a shift at right angles to the direction 

 of the force; at right angles therefore to the shift 

 that would take place if the wheel were not spinning. 



It is necessary to get this anomalous but invariable 

 gyroscopic action fairly in mind in order to under- 

 stand the stabilizing effects that are produced with 

 this wonderful apparatus. It should be recalled also 

 that the anomalous movement of the gyroscope is 

 called precession, and that the force which causes it 

 to shift its position is called a precessional force. 



With these simple technicalities in mind it is pos- 

 sible to understand all the results attained with the 

 use of the gyroscope. 



UTILIZING THE GYROSCOPIC PRINCIPLE 



Foucault's demonstration that the earth revolves 

 was made with the gyroscope as long ago as the year 



260 



