112 AN" EMPIRICAL STUDY OF GYRATING BODIES. 



or decreasing, and whether the body is frictionless or 

 not. 



THE EXPLANATIONS OFFERED BY COLLEGE TEXT BOOKS. 



The few that mention the gyroscope confine them 

 selves to showing, or attempting to show, that the rota- 

 tion of the wheel, combined with its downward motion, 

 under the action of gravity, results in a lateral move- 

 ment coinciding in direction with that of the under side 

 of the wheel. 



That the lateral resultant does not account for the 

 staying-up of the instrument is evident from the follow- 

 ing : 



It is a familiar principle; that, if the resultant of two 

 forces be replaced by an equal opposite force, the system 

 will be in equilibrium, and consequently at rest. If 

 this be attempted with the gyroscope, no single force 

 can be applied that will bring it to rest, except a verti- 

 cal one, and that is not the resultant claimed. 



It is easy to try it. Attach a cord to the free end, and 

 hold it — the cord — in the horizontal plane in which the 

 instrument is moving. Pull back on the cord ; instead 

 of coining to rest, and staying at whatever point it hap- 

 pens to be, it will instantly fall. The same result will 

 occur even though the string is held above the plane so 

 as, to some extent, to lift the instrument. 



A very brief trial will suffice to show that no single 

 force holds the gyroscope up. 



Those who have any desire to see what is said in col- 

 lege text books, can turn to pp. 111-113, of KimbalV s- 

 Olmstead? s College Philosophy ; or to Peck' s Mechanics 

 (with calculus) pp. 230 to 235 ; or to Loomis's Nat, 

 Philosophy, pp. 101 to 104 ; or to BracketV s Text Book 

 of Physics, 55-58. All have substantially the same 

 methods, and are open to the same objections. 



Enough, I think, has been said to show the need of 



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