206 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
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. 13-14.) 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 gyro- 
stat 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 flywheel is rotating, however, the top balances on the table. 
The two nonrotational instabilities have been stabilized. 
I now place the top on the table with the legs and axis of the fly- 
wheel vertical, but with the weight below the gyrostat. The arrange- 
ment is unstable. Here there is only one instability without rota- 
tion, and the result is instability with or without rotation. 
Here is a stilt-top similar to the one just shown, but 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 prvoted within a structure which 
represents a tight-rope balancer. The structure terminates in wheels 
adapted to engage on the wire. Attached to the gyrostat are two 
arms, and carried by these is a light rod weighted at both ends. 
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 
toward me, the gyrostat precesses in the direction which carries the 
pole over toward you, and vice versa. That is, if the balancer 
begins to fall over to one side it immediately 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 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 the wheels (a relatively 
small factor in this case) results in the erection of the machine. 
Similarly, if the machine tilts to the right the front Heute 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. 
