108 AN EMPIRICAL STUDY OF GYRATING BODIES. 



been no diminution, it would at any of these rates have 

 staid up "forever." 



To say the least, the statement appears extraordinary, 

 one might say incredible, but for the high position of 

 General Barnard and his endorsement by Sir William 

 Thomson. 



As this paper is an experimental study, we will see 

 what the gyroscope does when set going and left to 

 itself. 



I take my instrument (fig. 2), set the weight so that 

 the axis is horizontal. I then wind up the string on 

 the axle, as usual, and set the wheel in motion. The 

 machine remains at rest. I attach at the hook end a 

 small weight. Gyration commences. Very slow it is, 

 but so far as we can see, accompanied by no fall. I set 

 an index (a wire pointer attached to a retort stand) to 

 the level of the hook as it sweeps by. When it comes 

 around again I notice that it is now below the index, and, 

 next time still lower, it is falling. I now attach a much 

 heavier weight — say thirty-two ounces — really sixty-four 

 ounces, since the hook is so far from the point of sup- 

 port. I must now release the gyroscope with some skill, 

 or the shock may throw it off the standard. Practice 

 has enabled me to do this very smoothly. At once the 

 gyration commences — this time quite rapidly— the fall 

 increases in equal ratio. Perhaps it may be thought the 

 increased speed is due to loss of rotational velocity, as 

 the wheel by this time has lost much of its original 

 motion. I therefore take off my heavy weight and restore 

 my light one, and again leave it to itself. The gyration 

 recommences, but, though a little more rapid than at the 

 first, it is very much slower than in the second case. 

 I again apply the heavy weight ; the gyration and fall 

 become more rapid. I reduce the weight ; they become 

 more slow. Yet the wheel of the gyroscope all this 

 time has been losing speed, for what it now has is the 



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