J. G. Ba?'7iard on the Gyroscope. 49 





Art, VL — The Self- sustaining power of the Gyroscope analytically 



examined; by Maj. J. G. Barnard, A- M., Corps of Engi- 

 neers, U - S. A. 



After reading most of the popular explanations of the above 

 phenomenon given in our scientific and other publications, I 

 nave found none altogether satisfactory. While, with more or 

 less success, they expose the more obvious features of the phe- 

 nomenon and find in the force of gravity an efficient cause of 

 horizontal motion, they usually end in destroying the founda- 

 tion on which their theory is built, and leave an effect to exist 

 without a cause ; a horizontal motion of the revolving disk about 

 the point of support is supposed to be accounted for, while the 

 descending motion, which is the first and direct efiect of gravity 

 (and without which no horizontal motion can take place), is 

 ignored or supposed to be entirely eliminated. Indeed it is 

 gravely stai-ed as a distinguishing peculiarity of rotary motion, 

 that, while gravity acting upon a non-rotating body causes it 

 to descend vertically, the same force acting upon a rotary body 

 causes it to move horizontally. A tendency to descend is supposed 

 to produce the effect of an actual descent; as if, in mechanics, 

 a mere tendency to motion ever produced any effect whatever 

 without that motion actually taking place. 



Whatever ' mystification' there may be in analysis — however 

 it may hide its results under s\'mbols unintelligible save to the 

 initiated, it is most certain that the greater portion of the physi- 

 cal phenomena of the universe are utterly beyond the grasp of 

 the human rnind without its aid. The mind can^ndeed it 

 must — search out the inducing causes, bring them together and 

 adjust them to each other, each in its proper relation to the rest; 

 but fiirther than that (at least in complicated phenomena) un- 

 aided, it cannot go. It o^awwoi follow these causes in all their va- 

 rious actions and re-actions and at a given instant of time bring 

 forth the results. 



This, analysis alone can do. After it has accomplished this, 

 it indeed usually furnishes a clue by wdiich to trace how the 

 workings of known mechanical laws have conspired to produce 

 these results. This clue I now propose to find in the analysis 

 of rotary motion as applied to the gyroscope. 



The failure in most attempts at popular explanation arises, it 

 appears to me^first^ in attempting to account for that which is 

 not truCj viz., an absolute self-sustaining power in the rotary disc 

 in which all vertical motion is ignored ; secondly, in making 

 w^hat is only a particular and extreme phase of rotary motion, 

 an isolated phenomenon^ and in seeking causes for it without ref- 

 erence to the general laws of that motion. 



SECOXD SERIES, VOL. XXIV, NO, 70.— rJULT, JSi7. 



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