1918] on Gyrostats and Gyrostatic Action 048 



ings arranged on wooden uprights, and may be made to oscillate on 

 these bearings, so as to imitate the rolling of a ship in a cross-sea. 

 The frame of the gyrostat is mounted on two bearings placed athwart 

 the frame, and a weight is attached to the outside of the case in a 

 position in line with the axis of the flywheel. The centre of gravity 

 of the gyrostat is in line with the bearings. A clip-deyice is provided 

 which allows the gyrostat to be clamped to the skeleton frame, and 

 provision is made whereby a graded amount of friction may be applied 

 at one of the bearings. 



I now set the skeleton frame vibrating with the flywheel at rest. 

 You observe the period. I start the motor-gyrostat, and repeat the 

 vibrations, with the gyrostat clipped to the frame. The ship rolls 

 precisely as before. I free the gyrostat from the frame, and again 

 set the ship rolling, when you see that not only is the period vastly 

 increased, but the rolling motion is quickly wiped out. 



"When the gyrostat is clipped to the frame it produces no effect 

 upon the rolling motion. The couples opposing the rolling motion 

 arise from the precessional motion, and hence the gyrostat must be 

 given freedom to precess. In this connexion it is interesting to 

 observe that in 1870 it was proposed by Sir Henry Bessemer to 

 obtain a steady cabin for a cross-channel steamer by placing it on a 

 gyrostat with its axis vertical and supported on fore-and-aft trunnions. 

 This plan was bound to fail. The dependence of the effect on freedom 

 of the axis to precess, in a direction which is not that of rolling, was 

 not understood. We now see that the object would have been attained 

 by supporting the cabin on fore and aft trunnions and mounting the 

 gyrostat, within the cabin, on trunnions placed athwart the ship. 



Here is a monorail-top of new design (Figs. 13 and 14). The frame 

 on stilts represents the car, and mounted on pivots placed across the 

 frame is a gyrostat. Carried by a rod fixed to the frame of the gyro- 

 stat, and in line with the axis of the flywheel, is a weight. When 

 the frame is placed on the table so that the legs and axis of the 

 gyrostat are vertical, with the weight above the flywheel, the arrange- 

 ment is doubly unstable without rotation ; the system of gyrostat 

 and weight is usually mounted on the pivots, and the entire structure 

 is unstable about the line of contact of the feet with the table. 

 When the flyW'heel is rotating, however, the top balances on the 

 table. The two non-rotational instabilities have been stabilised. 



I now place the top on the table with the legs and axis of 

 the flywheel vertical, Imt with the weight below the gyrostat. 

 The arrangement is unstable. Here there is only one instability 

 without rotation, and the result is instability with or without 

 rotation. 



Here is a stilt-top similar to the one just shown, Irat provided 

 with wheels adapted to engage on a stretched wire. You observe the 

 remarkable balancing power of the arrangement. 



In this top (Fig. 15) a gyrostat is pivoted within a structure 



