s 



"7- 





MECHANICAL PARADOXES. 



The spinning gyroscope resists this tilting 

 as energetically (for its speed) as a bullet resists 

 being turned out of its path, simply by virtue 

 of the great law of inertia, the strong tendency 

 possessed by all moving things to resist inter- 

 ference with their motion. 



It has been mentioned that when the gyro- 

 scope is held by the knobs and an attempt 



made to tilt it by 

 * N F raising one knob and 



' \\ depressing the other, 



!\ \ it not only resists 



^ ^ this tilting, but seems 



to wrestle and twist 

 itself in another way 

 in the effort (not 

 always an unsuccess- 

 ful one) to wrest 

 itself out of the ex- 

 perimenter's grasp 



Fia. 9.-SECONDARY MOVEMENT ar , J pQp^-np f n fV,p 



CAUSED BY A TWIST. 



ground. 



This apparently extra twist which the gyro- 

 scope gives itself is really the consequence 

 partly of the tilt given by the operator, and 

 partly of the gyroscope's resistance to dis- 

 turbance of its movement. 



Fig. 9 will help to explain this. Let A B 

 be the gyroscope, seen, as in the last figure, 

 by a person in front of its edge, and let the 

 direction of the spin again be such that the 



32 



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