178 



NATURE 



[April 17, 19 13 



My assistant spins the flywheel and places the structure 

 upon the wire with the legs vertical and the pole 

 horizontal. The top, as you observe, balances on the 

 wire. If the top tilts over on the wire towards me 

 the gyrostat precesses in the direction which carries 



the pole over towards you, and vice versa. That is, 

 if the balancer begins to fall over to one side it 

 immediatelv puts over the pole to the other side. 

 The action" is exactly that of a tight-rope acrobat. 

 The rider of a bicycle keeps the machine upright by 



erection of the machine. Similarly, if the machine 

 tilts to the right the front handle-bar of the machine 

 is turned to the right. 



Here I have a small bicycle of the old-fashioned 

 "high" type provided with a gyrostatic rider. When 

 the gyrostat is spinning rapidly you observe that the 

 top is completely stable. The gyrostat operates the 

 front wheel, just as does the rider on the ordinary- 

 bicycle. 



Again, here is a small safety bicycle provided with a 

 gyrostatic rider (Fig. 16). In this case the gyrostat 

 is mounted above the back wheel, and is connected 

 by arms to the handle-bar of the front wheel. The 

 action is the same as in the other model. 



The tops I have shown you are very interesting 

 from the fact that in each case the gyrostat not only 

 detects but sets about correcting any tendency of the 

 top to fall over. It behaves as if it had both a nervous 

 and a muscular system. 



I have also here a gyrostat which can be made to 

 progress in space by a reciprocating motion — in fact, 

 a walking gyrostat" (Fig. 17). The gyrostat is sus- 

 I ended bv two chains from two horizontally stretched 

 wires. The wires are carried by a wooden frame, 

 which is mounted, as you see, on two trunnions carried 



operating the handle-bar. If the machine tilts over 

 to the left the rider turns the handle-bar to the left, 

 and the forward momentum of the bicycle and rider, 

 aided by the gyrostatic action of th. wheels fa 

 relatively small factor in this case) results in the 



XO. 2 268. VOL. 91] 



Fig. 16. — Gyrostatic bicycle rider. 



by wooden uprights. The chains attached to the aims 

 of the gyrostat terminate in two rings, and these are 

 threaded on the stretched wires. 



The gyrostat is spun and replaced on the wires. 

 When the frame is tiltud to and fro on the trun- 

 nions you notice that the gyrostat walks hand-over- 

 hand along the wires. By the tilting of the frame the 

 weight of the gyrostat is thrown alternately on each 

 of the chains, and in consequence of the precessional 

 motion the gyrostat moves along carrying the chains . 

 with it. 



At present the spin is great, and therefore the pre- 

 cessional motion is small. The gyrostat proceeds, as 

 you see, with a slow and stately motion. As time 

 goes on the spin falls off, and the rate of walking 

 increases, until finally the gyrostat literally runs 

 along the wires, with considerable loss of dignity. 

 When the gyrostat is enclosed in a box or within an 

 acrobatic figure, the behaviour seems very mysterious. 



Here is still another form of acrobatic top, consisting 

 of a large gyrostat, the axis of which is horizontal, 

 and two small ones, with axes vertical, mounted, as 

 you see them, one on each side of the large one, on 

 sleeves threaded on a horizontal bar. as shown in 



