C. B. WARRING. 141 



there can be no fall, and, hence, no gyration from that 

 source ; but the axis being oblique, the difference in the 

 moments of the friction (just as in tig. 21) causes the in- 

 strument to gyrate in the same sense with the side 

 which is farthermost from the support, i. e., with b, and 

 as is indicated by the directional ellipse B. 



If the angle the axle makes with the horizon is quite 

 large — 50° or 60° — and the hook is bent so that the point 

 is a little above the line of the axis, the instrument will 

 gyrate more and more rapidly, and soon begin to rise, 

 continuing till it reaches the vertical. 



Again : place the gyroscope as in fig. 24, inclining 50° 

 or 60° below the horizon. The side of the axle towards 

 a, being farther from the standard, the moment of the 

 friction on that side is the greater, consequently gyra- 

 tion commences in the direction of the arrow next to 

 a, or as indicated by the arrows in the ellipse A. If 

 now the cord is slackened so that c is free to fall, the 

 part a will (as in case of our tee-square) move with a 

 certain velocity to the right, and, when in its rotational 

 movement it has gone 90°, it will still have its motion to 

 the right, and that will push c away from us, and so 

 cause a gyration in the direction of the ellipse arrows 

 D. And so the gyration will continue in the direction 

 of arrows of A when the string is taut, and of D when 

 it is slackened. 



If, however, you pull the cord so that all, or almost all, 

 the weight is taken from the standard, p will now be 

 the end that can fall, and the instrument will gyrate in 

 such a sense that p moves from you and c towards you ; 

 in other words, the effects of gravity and of friction now 

 cooperate. The friction now accelerates the gyration, 

 and the effect of that, by our first law, is to make the 

 free end of the gyroscope rise. 



General Barnard says the free end will of itself leave 



125 



