0. B. WARRING. 143 



and axle of my medium-size gyroscope. The form is 

 peculiarly favorable to a clear exhibition of its peculiari- 

 ties. To adapt it to my purpose, I had several points 

 made of hardened steel, which screwed into a movable 

 socket, d, tig. 25. These "points" were centered, pol- 

 ished, and fitted with the utmost care, so that they are 

 as nearly "true" as possible. 



They are of various forms, as shown in the diagram. 

 Of truncated cones I have several, measuring across the 

 face from one-eighth to one-fiftieth of an inch. In all 

 cases, unless otherwise stated, the top was spun upon 

 a large pane of glass, laid as fiat as possible on an ordi- 

 nary table. From the point to the center of the wheel 

 measures one and three-quarters inches. The wheel is 

 three and three-quarters inches in diameter. The weight 

 is almost all in the rim. The whole weighs eight and 

 one-quarter ounces avoirdupois. 



A theoretical top revolves on a mathematical point 

 situated in its axis of figure and mass. The nearest 

 approach possible is my top with one of its very sharp 

 points. So soon as the point becomes so far blunted 

 that when turned towards the light any disk, however 

 small, can be seen, it is unfit for my purpose — the ex- 

 hibition of the theoretical top — and is laid away in the 

 box of truncated points. 



Until the contrary is stated, I shall use only the fine 

 points. 



If such a top be set going, it does not move about, nor 

 will it rise from an oblique to a vertical position. At 

 whatever angle of inclination the axis happens to be 

 when it starts off, at that it apparently remains, but 

 after a little time, one can see that the inclination is be- 

 coming larger ; the rim getting nearer and nearer to the 

 glass, while at the same time the gyration is growing- 

 more and more rapid. 



It is interesting to watch such a top as it whirls 



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