102 MOVEMENT 



just made some interesting experiments on the re- 

 sistance of metal bridges, by means of stylography 

 and chronophotography. He recorded vibrations which 

 proved that the metal arches of bridges were subject to 

 periodic strains. The diagrams showed that, if the 

 steps of a horse harnessed to a carriage harmonized in 

 rhythm with the natural vibrations of the corresponding 

 arches, the vibrations of the latter continued to increase 

 in amplitude, until the oscillation of the bridge became 

 thirteen times as great as when the carriage simply 

 remained at rest on the bridge. We regret that we 

 can do no more than simply mention this remarkable 

 fact. 



We cannot here extend the applications of chrono- 

 photography beyond the study of mechanical phe- 

 nomena. The reader will doubtless realize for himself, 

 from the instances already quoted, that such applica- 

 tions are extremely numerous. 



