WHAT KEEPS THE BICYCLER UPRIGHT? 77 i 



upon the subject. Gyration has nothing to do with it ; centrif- 

 ugal force has no application to it, except when turning corners, 

 or otherwise changing abruptly the direction of the movement ; 

 balancing is a detriment rather than an assistance ; * and rapid 

 motion alone accounts for nothing. Some other explanation is 

 needed ; this I shall now attempt to give. 



Regarded mathematically as a machine for the application of 

 force, the bicycle is a very simple affair. The weight (Figs. 6 and 

 7) is applied at the saddle, A, and is so great that the center of 



Fig. 6. An "Ordinary" Bicycle, with Lines of Force. 



gravity of the whole is very close to that point. A B and A 

 are the lines of force, B marking the point where the fore wheel 

 rests on the ground, and C where the rear one. In discussing the 

 forces that act on the machine we need consider only these lines, 

 all the other parts being merely for convenience or ornament. It 

 is evident that A can not of itself tilt either backward or for- 

 ward, since a vertical line from it falls between B and C. In 



* At the close of the reading of the paper, a teacher of the art of riding the bicycle, a 

 man of large experience, arose, and, in the course of his remarks, said that one of the 

 chief difficulties he had to contend with in teaching beginners to ride, was to induce them 

 to give up all idea of balancing; that till this was done they could not ride well a 

 striking corroboration of the theoretical conclusion arrived at by the writer of this paper. 



