100 AN EMPIRICAL STUDY OF GYRATING BODIES. 



instrument has its nearest approach to realization in a 

 finely-pointed, truly -centered top. At present we shall 

 consider the gyroscope as all have seen it. The other 

 will come hereafter. 



If the ring of fig. 1 be taken in the hand, or better 

 still, if it be held in the jaw T s of a vice (a small vice, such 

 as can be had for a dollar, we have found of very great 

 assistance if used to hold the gyroscope, when the ex- 

 perimenter is winding up the cord or drawing it out), 

 and a string be wound around one arm of the axle, and 

 then rapidly pulled — as boys sometimes spin a top — the 

 wheel will revolve with great rapidity. If, now, the 

 gyroscope be placed with the lug on the point, the axis 

 being horizontal and the hand withdrawn, some curious 

 results will follow. 



1. The unsupported end does not fall, and, for a con- 

 siderable time, the axle seems to remain horizontal. 



2. But, in fact, it begins at once to fall. 



3. It also begins to revolve around the point of sup- 

 port in that direction in which the underside of the 

 wheel is moving. 



4. The more rapid the wheel's rotation, the slower the 

 horizontal movement and the fall, and vice versa. 



I remark, that henceforth, through the whole of these 

 papers, " horizontal " will be used, for convenient brevi- 

 ty, in place of "apparently horizontal," or "approxi- 

 mately horizontal," except where it might cause am- 

 biguity. 



5. If I stop the horizontal movement by placing my 

 finger in its path the instrument instantly falls. 



6. If, by any means, as, for example, by a string at- 

 tached to the hook of the free end, I stop the downward 

 movement the lateral ceases at the same instant. 



7. If a weight be attached to the free end, the hori- 

 zontal and descending movement will both become more 

 rapid. 



84 



