APPARATUS FOE PHYSIOLOGICAL USE. 229 



other say two miles ; then I divide that distance into 

 quarters. Then, knowing that the train requires twenty 



Fin. 1. Diagram showing courses of trains from South Kensington Station to 

 Queen's Road and vice versa. The dotted line exhibits the progress of a train 

 running towards Queen's Road and stopping at each station ; the broken line 

 shows the progress of a similar train in the opposite direction ; the continuous 

 line that of a train running the whole distance without stopping. 



minutes to accomplish this distance, I measure off along the 

 horizontal edges twenty divisions. I divide it first into 



