MECHANICAL PARADOXES. 



not call upon it for a display of its paradoxical 

 properties until its spin is well established. 

 A mere loop on the string will do instead of 

 the wire ring, but will make a little more 

 friction, and will not last so long. 



When the wheel is not spinning, if we at- 

 tempted to get it to remain with the axis 

 horizontal while supported by the string at 

 one end only, the attempt would be a ludicrous 



FlQ. 7. HALF-CROWN GYROSCOPE. 



failure. How does the spinning make it possible 

 to perform what looks like a miracle ? 



Before attempting to make this clearer to 

 the non-mathematical, we will briefly consider 

 a few of the properties of the gyroscope in a 

 somewhat less simple form, one which can be set 

 spinning and held while spinning in the hands. 



Such a gyroscope is shown in Fig. 7, in which 

 A is the spinning wheel with a heavy rim, 



26 



