412 Proceedings of the Royal Society of Edinburgh. [Sess. 
A piece of apparatus in which a gyrostat is caused to imitate exactly 
the action of a human tight-rope balancer has been contrived by the author, 
and works perfectly. A framework to represent the body of the walker 
is mounted on two legs terminating in feet adapted to engage on a tight 
or slack wire. Mounted symmetrically on vertical pivots, carried by the 
framework, is a small gyrostat ; the line of the pivots and that of the feet 
lie in one plane. The gyrostat is so mounted that its axis is horizontal 
Fig. 5.— Gyrostatic Bicycle-rider. 
when the line of the pivots is vertical. Attached to the frame of the 
gyrostat are two small arms terminating in hands, in which are placed a 
light balancing pole weighted at both ends. If the framework containing 
the spinning gyrostat is placed on the wire with the line of the pivots 
in a vertical plane containing the wire, and the gyrostat is properly spun, 
and adjusted so that its axis is in a line at right angles to the vertical plane 
of the wire, the contrivance will balance. To bring about this result the 
direction of spin is made such that tilting over of the apparatus causes 
