TRANSACTIONS OF SECTION G. 761 



applied by the rider to the pedals is given out at the ground-point of the wheel in 

 the shape of back-pressure of the wheel against the ground. The more rigid and 

 unyielding the connection between these two parts of the mechanism is, the greater 

 will be the tendency to jarring of the feet by inequalities of the ground. Even on 

 smooth ground there is a jerk at the beginning of each stroke, in the case of an 

 unyielding wheel, which tends to fatigue the knee. The difference between the 

 energy given to the springs and the energy which they return is quite trifling in 

 comparison with the saving of energy which results from the easing-off of concus- 

 sions. Moreover, the energy stored in the springs is useful in carrying the wheel 

 past the dead-points, a small pressure unconsciously exerted on the pedals being 

 sufficient to retain the energy till it is wanted. 



An indirect benefit from lateral yielding is the diminution of side-slip. Side- 

 slip will begin as soon as the lateral force called out between the wheel and the 

 road at the ground-point exceeds a certain limiting amount. Lateral yielding 

 eases off the suddenness of lateral impulses, thus keeping down the maximum 

 amount of lateral force; and this is precisely what is required for preventing 

 side-slip. 



In some of the driving-wheels which the author has constructed the hub is 

 allowed to project much farther on the side remote from the driving-chain than on 

 the side next the chain, in order to permit the combination of a wide hub with a 

 narrow width between the pedals. AVeaker springs are used on the projecting 

 side than on the other side. This unsymmetrical arrangement is not found to 

 interfere with the ease of steering:. 



