84 



RECEEATIVE SCIENCE. 



That orhital and axial motioa are in- 

 timately related, and tliat the speed of one 

 may regulate that of the other. 



That the condition of unstable equili- 

 brium in which many bodies remain, is to 

 be explained by the fact of their rotation ; 

 as, for example, a child's top, etc., etc. 



Fig. 1. 



Examine the instrument while in a state 

 of rest, and it will be readily moved in any 

 direction, the slightest touch being sufficient 

 to alter the position of any of its parts ; and 

 if the stand be slowly moved round on the 

 table, the entire system of wheel, ring, and 

 arm wUl be moved round with it. 



Kotate the wheel by the aid of the string, 

 as before described, and a remarkable change 

 wiU be manifest. The wheel wUl now offer 

 a great resistance to any attempt to alter the 

 plane in which it is rotating, and the other 

 parts of the instrument, like it, seem to par- 

 take of a similar indisposition to be interfered 

 with. The stand may now be- moved round 

 on the tablft, but the wheel will not move 



with it ; the wheel and ring remaining ap- 

 parently immoveably fixed. If the instru- 

 ment be held in one hand by the stand, the 

 same takes place, whatever be the direction 

 in which it is moved. If the ring be re- 

 moved from the arm, while the wheel is 

 rotating, and held in the hand, the sensation 

 experienced is like that which would be felt 

 if it were a living thing struggling earnestly 

 to escape. 



When the wheel is at rest, hang one of 

 the cylindrical weights, H, on either of the 

 heads of the screws, e, f, that support the 

 axis of the wheel, and, as might be expected, 

 that side will, by the operation of the law of 

 gravity, be immediately pulled down. He- 

 move the weight, restore the wheel to its 

 vertical position and rotate it, and hang the 

 weight on again. The wheel now resists the 

 influence of the weight, and maintains the 

 position it was in before the weight was 

 applied, the rotation of the wheel apparently 

 neutralizing the law of gravity. 



Not only will the wheel retain its posi- 

 tion in spite of the influence of the earth's 

 gravity, represented by the weight, 

 but the entire system will commence 

 a rotation on the vertical spindle at- 

 tached to the semicircular arm. This 

 last rotation is due to the action of the 

 weight, for if this be lifted off the move- 

 ment instantly ceases, and commences 

 as soon as the weight is hung on again. 

 If the weight be hung on to the op- 

 posite end of the axis of the wheel, 

 the rotation of 

 the system on 

 the vertical spin- 

 dle still takes(; 

 place, but in the 

 opposite direc- 

 tion. 



E-otate the 

 wheel, and then ■^^*^- ^• 



remove it and the ring from the arm, and 

 hang them on to the end of a string by one 



