THi': c.vRoscoPK. 67 



Another action, which occurs both in the theoretical and 

 practical gyroscope, must not be left unmentioned. When the 

 apparatus is in operation and the axis not horizontal, the cen- 

 trifugal force of the mass around the pivot has some very 

 slight effect. When the axis is raised the result is as though 

 the wheel weighed more than it really does. When the axis 

 is depressed the result is to apparently lessen the weight. A 

 ver}'- slight alteration of the path due to this cause hence 

 occurs, negligible, however, in comparison with the effects of 

 friction. 



The action of the practical gyroscope therefore under ordi- 

 nary circumstances may be briefly summarized as follows : 

 When first released the axis describes a series of cycloidal 

 curves such as the theoretical instrument would describe ; in 

 other words, the orbit is nutating. Very soon, however, the 

 effect of friction in slowing down the wheel conies into play, 

 resulting in the transformation of the nutating path into the 

 uniform non-nutating helix already described, wherein the 

 gyroscopic force is just sufficient to counterbalance the attrac- 

 tion of gravitation. Henceforth this path continues until the 

 limits of operation of the apparatus are passed. 



