154 THE THEORY OF THE BICYCLE. 
satisfactory. Gyration has absolutely nothing to do 
with it. Centrifugal force has no application, save in 
turning corners, or otherwise changing abruptly the di- 
rection of the movement. Balancingisofnouse. Rapid 
motion accounts for nothing. 
Some other explanation is needed. This I shall now 
attempt to give. 
It will aid us if we omit from an ideal bicycle all 
that is not essential to our purpose. I will therefore 
draw on the blackboard two skeleton diagrams of the 
bicycle, representing the lines of force in the ordinary 
kind, 
Fig 6. 
A 
a PB 
and in the ‘‘ Safety,”’ 
Fig.7 
A 
re P B 
A is a point in the centre of the saddle; B is the point 
where the fore wheel touches the ground, and C where 
the other. A Band A C, therefore, represent the lines 
of force when the instrument is upright and at rest. 
The weight of the rider brings the centre of gravity of 
the whole instrument very near the saddle, 
104 
